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Learning, Sharing, and Teaching => Do it Yourself Discussion! => Topic started by: MrSal on November 17, 2017, 07:22:22 AM

Title: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: MrSal on November 17, 2017, 07:22:22 AM
I need to insulate my attic very quick since temperatures are dropping and after my renovation project the insulation up there is not very good.

It wasn't very good even before, where it only had blown in fiberglass at what I estimate at 7 inches or so, where some places had nothing at all really.

I am trying to price out insulation for several materials.

I plugged the info of the specs on each bag and then I normalized everything in calculator to see the cost.

I was keen on rock wool since we use that a lot in my country for decades. The fire resistance appeals me and also sound ... however the price seems to be outrageous ... it seems absurdly high even when compared to cellulose, so I am wondering if my math is wrong in these calculations.

R50 for cellulose gives me a total price of around 644 dollars (and this is before using coupons) ... it seems cheap and at half price of fiberglass bats even it seems TOO cheap ...

Any input in calculations and also materials choice? I was keen at rock wool but at that price - no thanks!

(https://d1ax1i5f2y3x71.cloudfront.net/items/1y3V190H102d1F3y3F1J/Image%202017-11-17%20at%209.27.33%20AM.png?X-CloudApp-Visitor-Id=819fdda56280ca6dace0ef7883cce40f&v=456f2d5c)


House is around 1100 sq ft ...

What is the weight of rock wool even? wouldn't that be a lot heavier than cellulose, hence the load on the ceiling and drywall would probably be too much? i cant find specs on weight on rock wool but i assume is much heavier
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: Cromacster on November 17, 2017, 08:11:48 AM
I can't speak much to roxul or much of the other options, but I installed cellulose into my attic and it's been working great.  I blew in about 18", which I think it's settled to about 14-15". 

It's cheap, it's mostly recycled newspaper thats treated to be fire and pest retardant.  It's also easy to install.  The hard part is preparing the attic.  You need to seal up all the cracks into the house and install baffles to allow airflow from outside.  If you already have this part done, cellulose will take you an afternoon to install.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: MrSal on November 17, 2017, 08:15:32 AM
I can't speak much to roxul or much of the other options, but I installed cellulose into my attic and it's been working great.  I blew in about 18", which I think it's settled to about 14-15". 

It's cheap, it's mostly recycled newspaper thats treated to be fire and pest retardant.  It's also easy to install.  The hard part is preparing the attic.  You need to seal up all the cracks into the house and install baffles to allow airflow from outside.  If you already have this part done, cellulose will take you an afternoon to install.

Not yet. I have baffles purchased already to keep the vents unobstructed.

I need to seal with foam the cracks etc which i already have the gun dispenser as well.

My Lowes, the cellulose bags are among the most expensive... there are places far from me with bags at more than half the price which baffles me!
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: MrSal on November 17, 2017, 09:00:45 AM
My energy supplier has rebate of 75% of cost up to 125$ so cellulose seems a no brainer ... with all said, the whole cost out of pocket on cellulose to r50 should be around 270 dollars or so ... saving me about 100-150 dollars per year ...
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: Sun Hat on November 17, 2017, 02:49:41 PM
I installed Roxul in my basement, and figure that it weighs roughly the same as fiberglass batting. I wasn't doing a comparison, but it's light, as fiberglass is also light. From my very limited knowledge, the main advantage to Roxul is that it won't mold if it gets wet. In a well-designed and built attic, this shouldn't be an issue. I know that Roxul also makes a "Safe & Sound" insulation product for sound and fire dampening, but I don't think that it has a particularly good R value.

I've been looking at adding additional insulation to my attic to boost from R25 to R60 and have found that cellulose seems to be the cheapest option here too.  Keep us posted on what you choose and how the installation goes.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: MrSal on November 17, 2017, 03:08:24 PM
I installed Roxul in my basement, and figure that it weighs roughly the same as fiberglass batting. I wasn't doing a comparison, but it's light, as fiberglass is also light. From my very limited knowledge, the main advantage to Roxul is that it won't mold if it gets wet. In a well-designed and built attic, this shouldn't be an issue. I know that Roxul also makes a "Safe & Sound" insulation product for sound and fire dampening, but I don't think that it has a particularly good R value.

I've been looking at adding additional insulation to my attic to boost from R25 to R60 and have found that cellulose seems to be the cheapest option here too.  Keep us posted on what you choose and how the installation goes.

I wanted to go with Roxul because of fire resistance - its pretty much unburneable -  but the cost is 4x more than celllulose so I am not sure.

If this were a new/renovation house where i had all walls open to the studs and could add insulation to walls, I would probably go Roxul most definitely... in this case I probably will go with cellulose.

now its only a matter of figuring out how to remove the fiberglass up there... ill probably DIY a vacuum since i cant find any nearby and the closest place that rents a vacuum for insulation it costs 300$ for the day... might as well do it myself with a dust collector motor probably...
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: tardis on November 17, 2017, 03:13:57 PM
Roxul is also hydrophobic.  If you get a leak you can pull it out, let it dry and stick it back n with no issues.  Cellulose = rotting mush at that point.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: Syonyk on November 17, 2017, 05:31:09 PM
I know that Roxul also makes a "Safe & Sound" insulation product for sound and fire dampening, but I don't think that it has a particularly good R value.

The R-value of the Roxul stuff is the same as fiberglass, give or take a margin of error.  I've got it in my office walls and I'm happy enough with it, though it's certainly not cheap.  I just hate working with fiberglass...
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: Sun Hat on November 18, 2017, 09:57:09 AM
now its only a matter of figuring out how to remove the fiberglass up there... ill probably DIY a vacuum since i cant find any nearby and the closest place that rents a vacuum for insulation it costs 300$ for the day... might as well do it myself with a dust collector motor probably...

Why not just blow the cellulose on top of the fiberglass? That's what a contractor that bid on upgrading my attic insulation was planning to do. I'm genuinely interested in knowing if this is a bad idea, as I'm likely to go this route, but DIY.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: MrSal on November 18, 2017, 10:52:57 AM
now its only a matter of figuring out how to remove the fiberglass up there... ill probably DIY a vacuum since i cant find any nearby and the closest place that rents a vacuum for insulation it costs 300$ for the day... might as well do it myself with a dust collector motor probably...

Why not just blow the cellulose on top of the fiberglass? That's what a contractor that bid on upgrading my attic insulation was planning to do. I'm genuinely interested in knowing if this is a bad idea, as I'm likely to go this route, but DIY.

Because i want to air seal the attic. Just blowing cellulose with no caution regarding air infiltration is a piss poor job.

It's a bad idea... i mean not bad per se since having more insulation than less is always better. But it's something that if you want to do it right, you need to airseal it otherwise the R60 or whatever, wont truly be that value since a lot will be lost in air infiltration.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: bacchi on November 18, 2017, 11:45:46 AM
A layer of the 2x4 Roxul for fire protection + sound insulation and then blow in cellulose?
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: paddedhat on November 20, 2017, 09:16:53 AM
In this application, fire rating is not a real concern. Cellulose is treated with a fire retardant, typically boron. It won't ignite due to an electrical short or other source. The other issue is that you have a fire rated layer of sheetrock between the living space and the attic. By the time the flame spread rating of the attic insulation comes into play, in the real world, the roof structure is burning, and there are structural collapse hazards. Hopefully buy then, there are firefighters on scene to deal with the issue, and you're safely out of the place. It isn't like a steel structure, where fire resistance is needed to preserve the structural integrity. IMHO, if you are in a situation where you have evacuated the building, (and with working smoke detectors, you will be safely outside in 99+% of all events) and the structure is so heavily involved that the ceiling insulation is on fire, all I want out of the entire mess is a foundation I can reuse. Let the rest of the thing go, a half burnt home is nothing but a massive pain in the ass.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: MrSal on November 21, 2017, 10:33:44 AM
ill definitely go with cellulose.

I managed to get a quote of 6 dollars per bag! Lowes sells it here for 12.95 ... a local yard sells the bag for 8 dollars ... I price matched it at Lowes+10% and then their 20% coupon ! I win :D

R60 for 418 dollars!
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: Papa bear on November 21, 2017, 10:38:53 AM
Why not blow in more fiberglass?  I personally like working with blown in fiberglass more than blown in cellulose. 


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Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: GuitarStv on November 21, 2017, 11:10:16 AM
Roxul is a better sound insulator/dampener, and is much better to deal with in case of a leak.  I'd lean towards that stuff personally.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: paddedhat on November 21, 2017, 12:27:12 PM
Roxul is a better sound insulator/dampener, and is much better to deal with in case of a leak.  I'd lean towards that stuff personally.
. Looks like MrSal scored cellulose for 1/13th of what an equal amount of Roxul is worth in his market.  Given that sound and leaks are typically secondary concerns (if that) cellulose has a well documented history of performance, and it is over $5,000 cheaper, I'm not seeing any logical reason to recommend Roxul. The downside that you didn't mention is that there is no way a batt install in a flat attic can ever perform as well as a blown in product. Far too many air gaps and fit issues around mechanical systems, wiring,light fixtures, etc... to stand a chance of matching cellulose in real world performance.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: MrSal on November 21, 2017, 12:39:21 PM
if this were a new house or where it was down to studs only i probably would go with Roxul .... however its damn expensive and as it was said, can't beat in terms of air sealing everything - i will still air seal all gaps i can see visually once everything is vacuumed.

Regarding why not fiberglass? Fiberglass does not have airsealing properties like cellulose does. it's essentially an air filter.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: GuitarStv on November 21, 2017, 12:55:57 PM
Roxul is a better sound insulator/dampener, and is much better to deal with in case of a leak.  I'd lean towards that stuff personally.
. Looks like MrSal scored cellulose for 1/13th of what an equal amount of Roxul is worth in his market.  Given that sound and leaks are typically secondary concerns (if that) cellulose has a well documented history of performance, and it is over $5,000 cheaper, I'm not seeing any logical reason to recommend Roxul. The downside that you didn't mention is that there is no way a batt install in a flat attic can ever perform as well as a blown in product. Far too many air gaps and fit issues around mechanical systems, wiring,light fixtures, etc... to stand a chance of matching cellulose in real world performance.

I've found that going up into the attic and moving around is a semi-regular occurrence in my home.  (One leak from the roof, one bathroom fan that needed replacement, running cable through the walls of the home, adding bracing for a ceiling fan in the master bedroom, adding bracing for a ceiling fan in the other bedrooms after the master bedroom worked out well, one exciting time chasing racoons out of the attic who managed to pry their way in, etc.)  I've been in the house for eight years now, and think I've been up at least once a year since we moved in.  My real world experience with blown in fluffy stuff is that after the first half dozen times that you trample all over it and then try to fluff it back up, you probably wouldn't be any worse off with batts.

I have blown in cellulose and have started wishing that it was batts which could be moved around and replaced, but YMMV.

:P
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: paddedhat on November 21, 2017, 01:16:35 PM
Compaction is an issue, though, truth be told, you are in your attic probably 10X more than the average homeowner. I have been pretty successful in "fluffing" everything by dragging  a plastic leaf rake up in the attic with me. Bottom line is, unless you install the Batts yourself and are obsessive with carefully carving them to friction fit every little obstruction, you will always be better off with loose fill in a flat ceiling. Racoons............they are amazing little bastards! I got called to a cape cod I built. A raccoon sat his furry little ass on a steep roof  slope and reached up to tear the soffit right off a Dormer. He then had access to his winter nesting area. Literally a fifteen pound little bugger had used his talented little paws to take the place apart.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: TomTX on November 25, 2017, 07:35:15 AM
Why not blow in more fiberglass?  I personally like working with blown in fiberglass more than blown in cellulose. 


Sent from my iPhone using Tapatalk

Effective insulation value from blown fiberglass is often far lower than cellulose - it is easy to "over loft" fiberglass, which allows airflow and severely reduces effectiveness. With the density of cellulose, any over lofting is self-correcting as it settles.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: Prairie Stash on November 30, 2017, 03:44:16 PM
Roxul is for walls that require fire rating; around furnace rooms for example. Absolutely required when fire is a concern.
Fibreglass is nice in attics, it doesn't mold.
Cellulose is the most environmentally friendly, sequesters carbon, also cheapest.

All the products will work well in an attic. If you do a return on your investment, estimating a 10-20% reduction on natural gas costs, you'll likely see the Roxul won't pay for itself (better off investing the money and getting a dividend every year to pay for heating costs). I like your table, I suggest adding the potential return on it, I used my natural gas bills (the gas portion), subtractng baseline natural gas water heater (july/august bills) and found out how much gas was for heating. Then estimated 20% reduction, based on thickness, the thicker you get though the worse the returns get (i.e. the first 6" does more than the last 6").

I did an attic upgrade last year, bats of fibreglass, I save about $100/year in gas and electricity (blower fan on furnace, less cooling in summer from AC). I installed it myself spent $550 on product and lost a day doing the installing.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: MrSal on December 01, 2017, 01:34:20 AM
Roxul is for walls that require fire rating; around furnace rooms for example. Absolutely required when fire is a concern.
Fibreglass is nice in attics, it doesn't mold.
Cellulose is the most environmentally friendly, sequesters carbon, also cheapest.

All the products will work well in an attic. If you do a return on your investment, estimating a 10-20% reduction on natural gas costs, you'll likely see the Roxul won't pay for itself (better off investing the money and getting a dividend every year to pay for heating costs). I like your table, I suggest adding the potential return on it, I used my natural gas bills (the gas portion), subtractng baseline natural gas water heater (july/august bills) and found out how much gas was for heating. Then estimated 20% reduction, based on thickness, the thicker you get though the worse the returns get (i.e. the first 6" does more than the last 6").

I did an attic upgrade last year, bats of fibreglass, I save about $100/year in gas and electricity (blower fan on furnace, less cooling in summer from AC). I installed it myself spent $550 on product and lost a day doing the installing.

Thanks for input.

Yes clearly I should make a table with the return. This table was just for me to get a quick grasp on price per square foot and per R to see what I could obtain.

Actually, the table above is already not up to date since I got a better deal.

I called a local yard lumber/builder and they carry cellulose at 8,19 a bag.

I went to Lowe's and had them price beat it and their 10% policy making each bag at 7,37$...

I also have 20% coupon for lowes making a price per bag of 5,89 per bag!!

I already ordered 75 bags  for a total of 442$... This will be about  R65 from my estimates...

Better even, my electric supplier pays me 125$ as a rebate... If I didn't have natural gas heat and electric they'd pay me 80% of the cost including installation.. But in this case because I have gas heat they max it at 125$

So about 300$ out of pocket... Our current R value was about 5" of fiberglass and poorly in some spots without anything at all.

I would value our R value at R15-19 at optimistic scenario... Also, because now we don't have a stairwell to attic which essentially was just a big chimney, I suspect with r60 our usage will fall quite a lot.

From my  calcs, we should save at least 100-120$ per year and in not considering the blower consumption. I think the 100$ is conservative... Even if it is just that, that's a 33% return not to mention a much better comfort compared to now - it feels a bit drafty
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: Prairie Stash on December 01, 2017, 08:42:29 AM
For comfort comparisons, wait till the summer! My external temps fluctuate from -40 to 110F throughout the year. So I noticed massive money savings from the winter heating costs, but the decrease in heat coming in during the summer is far more dramatic. It keeps all the solar heat up in the attic and vents it out before coming into my house. No longer am i at 80F (converting to American for y'all) and being stoic, it stays cooler longer in my house from opening windows at night.

Insulation isn't just for cold weather. Its exactly like a cooler in the hot sun keeping your drinks chilled. Just something else to look forward to :)

If you haven't installed the insulation baffle (the stuff that lets air in from the soffits), look into making your own from cardboard. Basically you staple cardboard to the joists, Youtube is your friend. Cellulose means you aren't worried about moisture, cardboard will work. Get them installed the day before, its a time consuming project and you don't want to waste time during the insulation install. They're cheap, but the home made stuff is cheaper.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: MrSal on December 01, 2017, 10:00:03 AM
Yes since electricity is more expensive than gas, it should also make quite the savings... however, the delta between outside temperature and interior temperature is not as high.

While my Heating Degree Days are about 5500 per year, I believe the Cooling Degree Days is only 900 ... and out of these 900 a lot we don't use.

Our walls are not that well insulated but since heat rises, if the heat/air inside my home does not have anywhere to escape, the outside air at least won't come in. That's why im going at extents of making sure i seal all openings and crevices in the attic and for the cellulose.

Once attic is done ill just seal  and insulate the rim joist as well...

I have been without insulation the past 2 days and I notice a comparison vs last year, mostly because I don't have a big stairwell now leading to attic, where the door had a big gap etc...im sure it acted like a giant chimney flute. My house during the night even at 25F has been hovering around 63F until 7 am, while last year it would delve into 50's ...so I cant wait to put R60 up there and enjoy the savings/comfort etc...

But yeah! Cant wait for summer too to check the differnece in AC usage... should i install a radiant barrier or no need? They are pretty inexpensive and it seems it can cut the attic temperatures by 30F or more

Regarding the baffle vents... I have them :) I got them from Lowes at a nice price... like 0.60 $ each ... cant remember how much i bought but it was like 35$ or so ... maybe less even
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: MrSal on December 03, 2017, 11:04:16 PM
I'm exhausted.

We just did the whole attic. It took us 2 days to do it.

Our house is a low pitch roof ranch... So, your can imagine how hard it was to put the baffle vents in place. I think it took me total about 10 hours to put the vents crawling between joists etc...

I attached them with a staple gun and at same time, I would put a little of roxul to serve as a dam so that the loose insulation wouldn't fall through.

One bag of roxul was good for my whole attic to do the baffle vents. I also air sealed with spray foam all junction boxes or any air/holes and also drywall joints I could find...

There is one thing I regret I didn't think before. I should have doubled the vents lengthwise, one after the other... Why you ask?

Because I was planning on doing 18'' and the insulation at the eaves is much lower... If I had put another baffle vent I could've sprayed there much taller... Now after the fact nor sure If worth it to proceed.

I also did a bit of a pig's pen around the attic entrance where I built a dam with 2*4 scraps and plywood. Wife is pleased with plenty of storage there with no need to ever adventure in the attic again... On the floor of this dam I used some foam boards I had laying around and some roxul leftover l...

Bought 82 bags of cellulose and it was pretty straightforward... Actually fun... The preparation is what was hard and laborious.

It's been 2 hours since my furnace kicked in and it is 24F outside and the 67F t-stat setting... Temperature is still 67...

It feels great so far...

Before, our furnace would kick regularly... We had about 4-5 in of loose fiberglass and in some spots nothing at all... Now we have about 13-14" of cellulose completely air sealed... Some spots have more because of soffit.... In those cases it might have 20-22" such as soffit on top of kitchen cabinets and bathroom (for some reason there's no drywall at same level... They just framed it out and plastered... So in the attic there are holes here and there)

Next I'll do the rim joist since we intend to finish the basement
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: Cromacster on December 04, 2017, 08:40:31 AM
Nice work!

The air sealing and baffles is definitely the the time suck, actually blow the stuff in is the easy part!
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: Syonyk on December 04, 2017, 09:01:58 AM
Wow, awesome work!
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: ManyMountains on December 04, 2017, 09:58:19 AM
How did you get 82 bags to your house? Was it delivered or did you rent a trailer to pick it up? I can't picture how much volume that would take up.

We have to house, our residence and a nearby rental, that are both about 1200 sq.ft and need more insulation. Currently have about 5" in each, and we live in SF Bay area, so should have 2-3x that amount. Thanks for everyone posting here as the info is quite helpful.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: MrSal on December 04, 2017, 10:11:46 AM
How did you get 82 bags to your house? Was it delivered or did you rent a trailer to pick it up? I can't picture how much volume that would take up.

We have to house, our residence and a nearby rental, that are both about 1200 sq.ft and need more insulation. Currently have about 5" in each, and we live in SF Bay area, so should have 2-3x that amount. Thanks for everyone posting here as the info is quite helpful.

Yeah quite the volume indeed.

We used my wives dad pick up truck ... it took us 3 trips total. Lucky for us, our Lowes is 1 mile away from us :)

This is a pallet of 28

(https://d1ax1i5f2y3x71.cloudfront.net/items/272v3a3b1k412s450s2o/Image%202017-12-04%20at%2012.14.39%20PM.png?X-CloudApp-Visitor-Id=819fdda56280ca6dace0ef7883cce40f&v=30b1dcb0)

Inside our little pig's pen aka insulation dam:

(https://d1ax1i5f2y3x71.cloudfront.net/items/1K3F3J1L3z2w1K3D1e0j/Image%202017-12-04%20at%2012.16.21%20PM.png?X-CloudApp-Visitor-Id=819fdda56280ca6dace0ef7883cce40f&v=25270a45)

I think there were still about 20 bags left to blow at this point
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: Prairie Stash on December 05, 2017, 08:48:51 AM
Our walls are not that well insulated but since heat rises, if the heat/air inside my home does not have anywhere to escape, the outside air at least won't come in. That's why im going at extents of making sure i seal all openings and crevices in the attic and for the cellulose.

But yeah! Cant wait for summer too to check the differnece in AC usage... should i install a radiant barrier or no need? They are pretty inexpensive and it seems it can cut the attic temperatures by 30F or more

Regarding the baffle vents... I have them :) I got them from Lowes at a nice price... like 0.60 $ each ... cant remember how much i bought but it was like 35$ or so ... maybe less even
(partial quote)
Although heat rises, there's also a lot of heat that radiates downwards from the attic. Most Attics are giant ovens in the summer with all the sunshine, mine gets extremely warm. Hot air rises, that's true, but heat doesn't rise. Heat, like sunlight, radiates in all directions, it doesn't rise on its own at all (it requires a transport mode). That little difference will pay off huge in the summer, there will be a lot less heat coming in from the ceiling than before (from conduction).
Three types of heat transfer:
Conduction - materials touching transfer heat (wood touching insulation, also touching the interior ceiling). This is why attic insulation is so effective, it slows conduction (the R value rating)
Convection - typically air circulation. That's what people refer to when they say heat rises, they actually mean the air rises due to thermal expansion while cool air is simultaneously dropping inside your house due to thermal contraction.The air is not necessarily going in/out of the house.  A leak free house will still have an interior convection cycle (even between window panes you can see convection).
Radiation - beams of energy that transfer heat on contact (solar is the most common), but you can also see radiant energy with thermal cameras.

Radiant barriers are for certain specific situations. They work extremely well in poorly insulated spaces...since there's a lot of problems. For the effort involved in installing it at this point, I would skip it. You won't see much in gains, due to your excellent insulation doing so much.

One last caution, check the attic in the next cold snap for moisture (frost). Make sure your baffles didn't accidentally get covered/blocked. Now that you have less heat going into your attic, the house isn't drying the attic out as much. Its fine if you have proper seals, there shouldn't be moisture anyhow, but a quick check takes 2-3 minutes. High heat loss promotes air circulation in the attic, low heat loss (well insulated) means low convection rates. In some older homes, the poor insulation was a design feature :(  I need to install continuous soffit vents in my house, the solution to low convection is to increase the amount of inlets/outlets.

No one likes the follow up step, since the project is 95% done who wants to do the final inspection 3 months later?
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: MrSal on December 05, 2017, 11:26:58 AM
i know that. You know what I meant when I said about heat rises regarding putting insulation in attic.

It;s one of the reasons why insulating your attic is probably the most bang for your buck due to the stack effect.

Agree that in the summer, that insulation will help a lot as well keeping the attic heat out! In contrast though, it might not help due to the thermal mass, once the night comes ... due to stored heat, it might keep radiating heat throughout the night for a little. It happens sometimes to new people that insulate attics finding themselves using AC more at night even though exterior temp is lower than interior temp ... we'll see how summer goes! I intend to probably place an attic/window fan in order to bring cool outside air as long as humidity is low ...
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: MrSal on December 05, 2017, 11:33:15 AM


One last caution, check the attic in the next cold snap for moisture (frost). Make sure your baffles didn't accidentally get covered/blocked. Now that you have less heat going into your attic, the house isn't drying the attic out as much. Its fine if you have proper seals, there shouldn't be moisture anyhow, but a quick check takes 2-3 minutes. High heat loss promotes air circulation in the attic, low heat loss (well insulated) means low convection rates. In some older homes, the poor insulation was a design feature :(  I need to install continuous soffit vents in my house, the solution to low convection is to increase the amount of inlets/outlets.

No one likes the follow up step, since the project is 95% done who wants to do the final inspection 3 months later?

What do you mean by cold snap? Getting really cold spell and checking the attic after it defrosts? Sorry, english is not my native language...

Regarding the baffle vents they are not blocked since I made sure of it. It has about 2 inches of clearance.. however, what I should have done was just extending the vent by overlaping 2 together ... I only realized this after the fact... it didn't even occur to me this situation. I could probably still do it even though theres insulation all over, i imagine extending them would be easier since the pitch where they currently are is pretty OK now ... and extending them would only make the pitch better.

Regarding to check for moisture... should i check when? Within the next few months? And what should I look for and where?

Thanks so much for input :)
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: MrSal on December 05, 2017, 11:36:23 AM
To walk around half of the attic is pretty easy since I have a 13 in LVL beam - you can see in the picture above when it was not covered yet - and I know exactly where it is placed and it has only about 2" of insulation on top of it which would be easy to replace back
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: paddedhat on December 06, 2017, 04:59:52 AM

.. Some spots have more because of soffit.... In those cases it might have 20-22" such as soffit on top of kitchen cabinets and bathroom (for some reason there's no drywall at same level... They just framed it out and plastered... So in the attic there are holes here and there)

Next I'll do the rim joist since we intend to finish the basement

Sal, the lack of drywall above soffits is pretty much a result of how construction is done, here in the states.  The right way is to, first insulate the wall area behind the soffit, if it's an outside wall. Next  sheetrock the areas behind the soffits. Then mud and tape a first coat, as an air sealing barrier. Then the soffits are framed, and end up getting sheetrocked as the rest of the house is done. I've always done them this way, but very few builders do. It really screws up the flow of production building, since it requires a framing carpenter and the sheetrock contractor to do small, unscheduled visits, and adds to the costs.
Great job on the attic. I just had a highly reputable local cellulose contractor stop by. The guy who showed up was the project estimator, not a "salesman".  I wanted his opinion on how to proceed with some really odd problems in my attic. He told me that the can do time and material billing as an option. They charge $60 hour per man, and $12 bag.  So  by that metric, you saved a huge amount. (OTOH, they can blow 110 bags an hour, if they are going full throttle, LOL)
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: MrSal on December 06, 2017, 09:16:18 AM
110 bags per hour?!?!? That sounds so hard to believe damn!

I was doing maybe 20 per hour and it was already fast i can't imagine a rate 5x faster...
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: paddedhat on December 06, 2017, 09:37:22 AM
110 bags per hour?!?!? That sounds so hard to believe damn!

I was doing maybe 20 per hour and it was already fast i can't imagine a rate 5x faster...

One or two men, inside of a giant box truck, feeding a gas engine powered, Industrial grade blower six times the size of the free loaner unit from Lowes,  and a guy on the hose. A company that's done nothing but blown insulation for the last 40 years, and an experienced crew. A lot like the difference between when I hang drywall by myself, compared to when the pros. that hang a 80-100 houses a year, show up.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: Syonyk on December 06, 2017, 10:10:33 AM
One or two men, inside of a giant box truck, feeding a gas engine powered, Industrial grade blower six times the size of the free loaner unit from Lowes,  and a guy on the hose. A company that's done nothing but blown insulation for the last 40 years, and an experienced crew. A lot like the difference between when I hang drywall by myself, compared to when the pros. that hang a 80-100 houses a year, show up.

Seriously.  Don't underestimate the folks who literally "do this stuff for a living."  They don't screw around with homeowner grade nonsense.

When you're paid by the job, there are plenty of ways to speed stuff up.  Those trucks and blowers are expensive, but they pay for themselves, many times over.

And I agree with paddedhat on the drywall guys.  They'll show up at 6AM and have a whole house drywalled, taped, and mudded by the time I can get a few panels up.  They're insanely good at their jobs.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: paddedhat on December 06, 2017, 10:44:10 AM

And I agree with paddedhat on the drywall guys.  They'll show up at 6AM and have a whole house drywalled, taped, and mudded by the time I can get a few panels up.  They're insanely good at their jobs.

This why I always laugh at the clowns that have the stupidity to call any other ethnic group stupid or lazy. I had a Mexican drywall hanging crew that would show up with a foreman, and 5-6 tradesmen. They got to the job at 7 am, and typically by 11 or 12 they were sweeping the floor, and loading the van back up. The workmanship was as perfect as humanly possible, and watching them was to see poetry in motion. Not a wasted move, no down time ever. Just an extraordinary mix of skill, experience and devotion to doing thing fast and well.
Title: Re: Insulation of attic - Roxul or Cellulose?
Post by: MrSal on December 11, 2017, 12:23:07 PM
And finally the ended result with more insulation added in.

The LVL is not showing and the attic is now at 19" where possible. Junction boxes I screwed them to the tie ins as well as most wiring.

You can see slightly the dam that I built around the ceiling opening - that I cut in the hallway closed ... about 25'' wide :D ... The dam/pig pen is around 70'' x 70'' and can hold a lot of stuff.

Mrs Sal is excited because a lot of boxes can go up there. I did a quick math and it can hold about 20 totes ... 40 if you stack them. Only thing to take into account is the load ... how much weight could be put up there? Would 20-30 totes be worrisome? Would the joists in the attic take into account how much psf load? 30? Anyhow, most things are just out of season clothing... some pottery and other miscellaneous stuff... I wouldn't be much concerned because the closet walls are holding the load right there on the joists.

(https://scontent.fwbw1-1.fna.fbcdn.net/v/t35.0-12/25319886_10159808214735074_799005008_o.png?oh=0e53d5b73d81be8abc46b6002f8f54e9&oe=5A318BEB)

(https://scontent.fwbw1-1.fna.fbcdn.net/v/t34.0-12/25359982_10159808214955074_2018241603_n.png?oh=a96edb1c944c16eefeaeabfb3d9ddc3c&oe=5A319D94)
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: MrSal on December 12, 2017, 02:51:17 PM
Looking for advice...

I am about to start insulating the rim joist as well since we have a big opening from the island to the basement and it figures that we should insulate there since it's not tight at all.

Since we will be finishing the basement as well I figured it would just make sense to insulate it.

I was going to do Roxul around the rim joist/sill plate because it's more maleable than xps panels and cutting all obstacles would be a pain... however I found this article:

http://www.finehomebuilding.com/2013/09/12/insulating-rim-joists

Quote
The time-honored practice of insulating rim joists with fiberglass batts is no longer recommended. Because fiberglass batts are air permeable, they do nothing to prevent warm, humid interior air from contacting the rim joists. During the winter, when the rim joists are cold, condensation can cause mold and then rot.

To prevent these problems, only airimpermeable insulation—either rigid foam or spray polyurethane foam should be used to insulate the interior of a rim joist. Two-story homes usually have another ring of rim joists above the first-floor ceiling. If you need to insulate these rim joists, it’s best to hire a cellulose-insulation contractor.

My question is, can I use Roxul in this? It brings cellulose to the question since the yadvise it so i assume it would be okay for Roxul as well?

Using cellulose for around the rim joist probably is doable? I would have to use fabric stapled to the sill joist which I can imagine being a pain cutting everything one by one ...

My idea was to just use spray foam can and bead it around the edges and the place a cut piece of Roxul to it ... by my calculations only 1 bag would be needed for R15 to go around the whole perimeter.
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: Prairie Stash on December 15, 2017, 10:41:46 AM
For attic moisture, just check it a few times over the winter. If you have a problem, it will be obvious, a wet puddle. If you don't see wet insulation, it means the soffits are allowing enough air in to keep things dry. Every attic has some moisture (air contains moisture, it will condense with temperature swings, it turns to frost on nails in my area), its pooling water to watch for. Specifically around the attic entrance, if you have a poor seal there you'll have moist air from the house entering the attic and condensing. In time this can accumulate, unless the soffits dry it out enough. The drying process happens better in poorly insulated attics, the heat from the house helps the drying. Its a lot cheaper to have more soffit air flow.

Use foam board (1-2" thick) for rim joists and seal around the foam board. Its the same as doing spray cans, but a lot cheaper/easier. Cut the board to roughly the right size, put in place and seal with the spray. In the hands of an amateur like myself its too easy to put too much foam in place and it won't expand properly, the foam board takes care of this problem as well. With the foam in place you won't have moist air going through the Roxul or Cellulose and being trapped against the wooden joist, just a bead around the edge isn't enough, the foam needs to cover the entire joist face. If you see the rim joist after you've finished, its a problem.

Since you then have a perfect seal, Roxul is fine to increase the insulation value after. Roxul has fire retardant properties, make sure the foam board does too.
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: MrSal on December 22, 2017, 08:55:15 AM
Thanks great tips!!

The auditor from my electrical company just came to the house yesterday to check the work for the rebate... He said I did a better work that 98% of contractors/builders ... he even asked me if I was an engineer, because I started talking about coefficient values and U values etc... that was nice to hear.

He had a FLIR imaging camera and we got to see everything... roof was pretty much all covered with exception in some corners - which i was not surprised due to the very low pitch by the eaves... so not much insulation there.

However, he disclosed to me something that made me sort of "pissed" of the timing ... since I have NG my rebate isnt as big due to me only having AC... my NG supplier does not offer rebates, however he stated they are starting Jan 1st with rebates as well ... that would have been easy 400$ probably ... oh well life goes on :D
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: MrSal on January 25, 2018, 11:31:06 PM
So... I just received my gas bill and wanted to give everyone an update!

Even though last year I was already doing "aggressive" setbacks, due to this reason, I didn't expect as much savings! When you have a setback, because in essence you just make the house lose less heat, therefore slowing down the transfer of energy I didn't think the savings would amount to this, since I still keep doing the setbacks, even though not as aggressively.

So! My bill was essentially the same! I used -1 CCF for the same period as last year. HOWEVER! two things!

This year, our normal temperature on the t-stat has increased from 65-66F last year to 68F this year. The setback temperature went from 55F during the night to 60F (wife's imposition :D )

Also, the average daily temperature for the month this year was 22F vs 33F last year!

All in all, after calculating for HDD this month we lost 4.5 BTU/HDD/sq foot vs 6.75 BTU/HDD/sqft last year!

Thats 30% savings/improvement, while raising the average indoor temperature at the same time!!
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: Sun Hat on January 26, 2018, 08:59:07 AM
Woot Woot! Congratulations on a job well done!
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: Prairie Stash on January 29, 2018, 11:43:34 AM
Impressive! thank you for the update.

How long do you estimate the payback period will be? I bet its an impressive return on your efforts.
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: MrSal on January 30, 2018, 07:39:38 AM
Impressive! thank you for the update.

How long do you estimate the payback period will be? I bet its an impressive return on your efforts.

We don't spend much in heating to begin with because we have a small house - 1150 sq ft - and the house being at 58-60F for large duration of the day.

The house is 1150 sq ft however the furnace has about 4 vents in the basement (not finished) so not sure if I should consider the heating area as 1150 or 2300 sq ft...

The cost out of pocket for the 90 bags or so was about 400$... Our average usage I think is 400 CCF... So I'm assuming a 120 $ savings per heating season. So 3 years payoff maybe? No idea how much savings I'll get during summer for not using AC as much.

Last month is probably the highest bill since my wife stayed home 24/7 during 2 weeks (she's a teacher)...
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: Prairie Stash on January 31, 2018, 07:51:05 AM
Impressive! thank you for the update.

How long do you estimate the payback period will be? I bet its an impressive return on your efforts.

We don't spend much in heating to begin with because we have a small house - 1150 sq ft - and the house being at 58-60F for large duration of the day.

The house is 1150 sq ft however the furnace has about 4 vents in the basement (not finished) so not sure if I should consider the heating area as 1150 or 2300 sq ft...

The cost out of pocket for the 90 bags or so was about 400$... Our average usage I think is 400 CCF... So I'm assuming a 120 $ savings per heating season. So 3 years payoff maybe? No idea how much savings I'll get during summer for not using AC as much.

Last month is probably the highest bill since my wife stayed home 24/7 during 2 weeks (she's a teacher)...
I wish all my money saving ideas had 3 year pay offs. On a ROI that's an amazing amount (about 24% returns). 

If it makes you feel even better, it takes $3000 in savings to fund an extra $120/year. The power of reduced spending is greater than increased savings. I get its almost impossible to fine tune savings/spending to that degree, but you did create some extra room.
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: Clara Smith on February 03, 2018, 12:58:48 AM
I prefer Roxul, its fiberglass is light and easy to carry. And also it won't mold if its get wet.
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: MrSal on April 17, 2018, 04:33:27 PM
During the weekend the temperatures around here were 86F during the day... I had a first glimpse maybe of how the insulation may perform during summer.

While I am not sure of anything yet, a high temperature would put the house into the 70s easily during a hot, clear sky day.

Well, I was happy to leave the house at 65F, and when I returned home at around 5PM or so... all windows were closed and the temperature was 66F !

Temperature at night didn't go that low - around 75F at night - and temperatures next day were in the mid 80s as well ... temperature kept at a nice 66-68F during these 2 days! Can't wait to confirm performance during summer!

Only time house went above 70F was because my wife oepened the windows and pateo doors at end of day - and it went to 71F ...
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: Pennycounter on April 26, 2018, 10:02:11 AM
Nice! We also insulated our attic last fall and enjoyed it through the winter but we don't have AC so I'm really hoping it performs in the summer. 
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: MrSal on May 02, 2018, 03:35:49 PM
Nice! We also insulated our attic last fall and enjoyed it through the winter but we don't have AC so I'm really hoping it performs in the summer.

So far I am very happy. Yesterday was 85F and today is 89F ... just got home and the house sits at a very nice 70F !!!

I want to see how it performs during the actual summer.... but so far it seems very promising! At this pace, I dont think we will need much AC ... and our walls are not even that well insulated I think...
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: MrSal on June 16, 2018, 12:50:45 PM
Update... its been higher 80s the past 5 days or so ... tomorrow again 89 and the next day is 95 ...

I have rarely used AC so far this year - total about 2 hours and because my wife is picky at times :D ...

Right now the house is sitting at 73F and last time we used AC was more than 2 weeks ago.

However, I do have an Airking which I have been trying... at end of day during a hot day, especially if it's a stretch of hot days, the house may get to 76-77F around 7-8PM ... usually we a couple windows and turn it on. In 30 minutes or so the temperature goes from 76F to 71 inside. The fan is a great way to "reset" the temperature everyday for the heat the next day.

A thing I have noticed today though, is most likely the performance will increase even more. The sill plate is not yet insulated, and while my house sits at 73F The first 2 feet of flooring next to the exterior walls are at 79F or so... probably a lot of leakage coming from the sill plate.

Since we are finishing the basement, this area will be one of the first to tackle.
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: MrSal on June 18, 2018, 11:52:53 AM
96F air temperature at overcast ... under the sun is probably 100+ ... sidewalks are at 120F

Obviously, there are no miracles with this type of heat considering mostly that our walls I doubt there's much insulation there and being leaky I am sure ... currently the house sits at 79F and haven;t used the AC.

I wasn't able to use the Airking fan last night because the low during the night was only 74F, so the house wasn't able to get that low with the fan... luckily these hot muggy nights are not the norm... tomorrow the low temps at night go back to high 50s/low 60s
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: Pennycounter on June 19, 2018, 10:27:36 AM
Awesome update! We are loving our insulation as well but the results are noticeable but not as great. The back of the house is direct West facing and the windows have no low-e and since we have a large patio, there is not much shade.  Either way its better than last summer and we don't have AC! 
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: Sun Hat on June 20, 2018, 06:43:54 AM
I insulated both my walls and attic with cellulose this past winter and can really notice the difference. My furnace ran much less over the winter, despite it being very cold outside. Now that it's quite hot out, the indoor temperature increases about 2-3C over the course of a day with a 15C differential to outside, which is quite a bit better than before. I run the fan and AC for the sake of my my fluffy dog, who enjoys draping himself over the cold air vents.

Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: MrSal on July 13, 2018, 11:35:24 AM
For those that never insulated and lack insulation in their attic... DO IT!

It's ridiculous... just got my 2nd report...

June I have used a total of 18 hours of AC - we had a lot of muggy days where even at night we couldn't open the windows and temperatures in the high 90s low 100s.

Total CDDs for June this year is in the 320s while last year it was in the 280s (so in essence this summer has been about 14% hotter) ...

Even then, we have used 18 hours of energy vs 46 hours last year!

Last year, during high 90s days or something, the house would easily climb into the 80s sometime in the afternoon... right now, at end of day around 6PM-7PM once the sun starts hitting the west side windows, and during the high 90s days... then yes our house hits the 78-79F range ... but during the day the AC rarely kicks on.

It went from an average of 1.5 hours daily to 35 minutes a day of AC usage!

For the past 60 days we have used 25 hours of AC vs 61 hours of AC last year.
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: zoochadookdook on July 16, 2018, 07:51:25 AM
This looks like quite a job;

I'm getting my insulation done this month (did my roof last year DIY and after ice damming in the winter and it being hot in the summer just about had it with ventilation and soffits).  Going with a smaller local family owned company with a good rep.

I believe the quote for insulation r49 blown in top and front attics/baffles front/rear and interconnection (cape cod style with a front and top attic), a radiant barrier in the front, a ton of can vents, a upstairs bathroom fan vent and exhaust, and 12 new soffit vents is $1500. Rebates and such from the energy company and taxes will bring it to about 1250. If paid in cash (can be split into 3 payments) they'll knock 5% off. I could go r61 for another 150 or so which i'm considering (live in Michigan).
 
This seems way more reasonable than the "big company quotes I had for 3k or so; otherwise I would be DIY'ing.

On that note does anyone have experience insulating basements? I framed my basement 1/4" off my wall, ran the electrical and then realized the way to do it was to use that foam board and frame onto that. (I'm 25, a youtube builder on the weekends, database student during the week so by no means am I a professional). I've heard batts will mold due to moisture through the foundation. Is there any sort of "bagged batt" or something similar or should I look at cuttings foam inserts/spray in foam (pricey) as my options? This has to happen before I can start the drywall and flooring....of course I still have to get the plumbing for the bathroom figured out.

Thanks!
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: MrSal on July 16, 2018, 01:16:38 PM
This looks like quite a job;

I'm getting my insulation done this month (did my roof last year DIY and after ice damming in the winter and it being hot in the summer just about had it with ventilation and soffits).  Going with a smaller local family owned company with a good rep.

I believe the quote for insulation r49 blown in top and front attics/baffles front/rear and interconnection (cape cod style with a front and top attic), a radiant barrier in the front, a ton of can vents, a upstairs bathroom fan vent and exhaust, and 12 new soffit vents is $1500. Rebates and such from the energy company and taxes will bring it to about 1250. If paid in cash (can be split into 3 payments) they'll knock 5% off. I could go r61 for another 150 or so which i'm considering (live in Michigan).
 
This seems way more reasonable than the "big company quotes I had for 3k or so; otherwise I would be DIY'ing.

On that note does anyone have experience insulating basements? I framed my basement 1/4" off my wall, ran the electrical and then realized the way to do it was to use that foam board and frame onto that. (I'm 25, a youtube builder on the weekends, database student during the week so by no means am I a professional). I've heard batts will mold due to moisture through the foundation. Is there any sort of "bagged batt" or something similar or should I look at cuttings foam inserts/spray in foam (pricey) as my options? This has to happen before I can start the drywall and flooring....of course I still have to get the plumbing for the bathroom figured out.

Thanks!

I am currently insulating my basement:

(https://cl.ly/swIL/Image%202018-07-13%20at%201.46.51%20PM.png)

2 inch XPS glued against the wall ... also XPS on sill plate .... taped with a good european tape and also some foam can... and sealed on ground and top with more foam...

Starting now the build with metal studs and running electrical


Scour craigslist for deals on foamboard... there are plenty around ... i got this on CL for maybe 60% off retail price. They were used but as you can see pretty good condition.
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: zoochadookdook on July 16, 2018, 01:20:01 PM
Yep that's the way I SHOULD have; unfortunately all my exterior framing is done by now
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: DoNorth on July 17, 2018, 07:46:39 AM
I used 2x6 $-22 Roxul bats through my whole house (I live in the upper peninsula of Michigan) and pictured framed the cavities with acoustic caulk.  Closed it in with smart vapor barrier.  I used foam in all the rim joists and about 20" of blow in cellulose after I used the federal home energy guidelines for air sealing the attic.  My place is about 2850 sq. ft, and so far my place is one of the coolest along our stretch in the summer and I can heat it for about $1000/winter if using only propane or less if I'm burning mostly wood.
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: zoochadookdook on July 17, 2018, 10:06:34 AM
I used 2x6 $-22 Roxul bats through my whole house (I live in the upper peninsula of Michigan) and pictured framed the cavities with acoustic caulk.  Closed it in with smart vapor barrier.  I used foam in all the rim joists and about 20" of blow in cellulose after I used the federal home energy guidelines for air sealing the attic.  My place is about 2850 sq. ft, and so far my place is one of the coolest along our stretch in the summer and I can heat it for about $1000/winter if using only propane or less if I'm burning mostly wood.

I'll look into it; I'm leaving the ceiling unfinished and just spraying it black but my joists are all stuffed with batts right now. Still have to seal where mice were burrowing in against the house -____-. What do you mean by smart vapor barrier vs standard? Roxul is more water resistant? Caulking i'll have to check out as well. I was considering cutting a bunch of foam board down, gluing it in the cavities and spray foaming the gaps


 Hoping when they seal and do all the attic work next week it makes a fairly drastic difference in the bills.
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: DoNorth on July 17, 2018, 10:16:58 AM
smart vapor has a membrane that closes it cells in the winter when the humidity is high inside which keeps the humidity from passing through and condensing with cold air that infiltrates the building envelope.  It does the opposite in lower humidity and allows drying if there is wind driven rain etc.

I was going to use standard 6 mil visqueen, but opted for the smart barrier instead and then I bought a higher end air exchanger (HRV) in Canada for about $600.

Foam tends to crack when the building flexes or you have truss lift and therefore pulls apart.  Acoustic caulking is difficult to deal with, but stretches with the movements and keeps a nice seal.  I would buy a mechanical caulking gun and get the big tubes if you decide to use it.  The foam board and spray foam is a good budget friendly insulating technique.  To be clear, I used the smart vapor barrier on the walls, definitely not in the attic.
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: zoochadookdook on July 17, 2018, 10:22:48 AM
smart vapor has a membrane that closes it cells in the winter when the humidity is high inside which keeps the humidity from passing through and condensing with cold air that infiltrates the building envelope.  It does the opposite in lower humidity and allows drying if there is wind driven rain etc.

I was going to use standard 6 mil visqueen, but opted for the smart barrier instead and then I bought a higher end air exchanger (HRV) in Canada for about $600.

Foam tends to crack when the building flexes or you have truss lift and therefore pulls apart.  Acoustic caulking is difficult to deal with, but stretches with the movements and keeps a nice seal.  I would buy a mechanical caulking gun and get the big tubes if you decide to use it.  The foam board and spray foam is a good budget friendly insulating technique.  To be clear, I used the smart vapor barrier on the walls, definitely not in the attic.

My attic is getting done next week; I hired out but for the 80ft of baffles/combining the 2 attics from the dormer crawlspace to the top/sofits/vents/bathroom vent/radiant barrier and blown in 49 I didn't consider the price too bad. I mathed out materials to be around 900 for me plus at least 20 hours. With rebates from the energy provider and taxes I should come out to around 1250. 350 is easily worth 20 hours of my life spent crawling in the low pitch and front attic.

The basement on the other hand I would have done foam on the wall and framed off of if I hadn't been in a hurry to frame. The smart barrier is a good point; from what I read the issue with vapor barriers was the trapping of humidity so the fact they have one that opens and closes is pretty awesome. Closed cell would be ideal except $$$$$.
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: DoNorth on July 17, 2018, 10:40:50 AM
yes, I completely agree on the crawling around.  I built my place new and very custom, so while the walls were still open and not ceiling had been installed, i insulated the 2nd floor rim joist, I used trusses with energy heels and once the roof was on, I put baffles down into the soffit, stapled them in, and taped them.  The energy heel plus a cut batt for the rim joist eliminated any windwashing concerns you get with only blown in cellulose or fiberglass and then I just blew the cellulose right up to and over the rim joist cut bat against the energy heel part of the truss.  As long as you don't accidentally blow a bunch of insulation down your baffle, you're fine.  I was quoted about $22000 to do my whole place with closed cell.  AFter a lot of research, Roxul, plus a few foam kits and a lot of meticulous cutting gave me about the same results for just over $2500.
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: MrSal on October 26, 2018, 07:48:32 AM
I am totally surprised by this, but my house feels amazingly comfortable now that the temperatures have been hitting 30-32 consistently. Lows during night are 30-32 and highs around mid/low 40s

We haven't turned the furnace on yet and our house the lowest it's been so far is 64F. I attribute this to the basement insulation - 60s ranch house, single floor with basement. I can't exactly recall the behaviour last year when temperatures started to hit 30F but I think the house was cooler.

After further investigation, I saw some articles stating that you can save further 30% by insulating basement.

Even my wife that is very picky with temperature - usually she needs temps around 67-68F has been walking comfortably around the house at 64F - sometimes during the day we get to 65-66F (we don't have South facing windows unfortunately or we might don't even need heat for 90% of time!

By the way, quick question, now that I am framing the walls... do I need insulation inside the stud bay? Or can I leave it empty - which I would rather in order to leave upgradeability of utilities in future. Is this against fire code or something? Does the stud cavity need to be filled with something?
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: zolotiyeruki on October 26, 2018, 07:59:26 AM
Framing the walls in your basement?  It depends on where you live.  In my area, the local code says you have to have a fire break (or block, I forget which is which) between the stud bays and the joist bays above.  I.e. fire should not have a clear path to spread from inside the wall to inside the floor above.  Practically speaking, it means that any gap between the top plate of the new wall and the existing basement wall has to be filled/blocked with 3/4" plywood or better, and all penetrations through it must be sealed with fire-rated caulk or foam.  Insulation doesn't count, either. If it were me, I'd add insulation anyway, because A) it's cheap and adds comfort, and B) upgrading utilities in the future isn't super likely.
Title: Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
Post by: MrSal on November 22, 2018, 12:41:24 PM
So... quick update on this!

We insulated the rimjoists this summer along with basement wall with R10 XPS.

I slealed everything with foam gun and with SIVA tape - to those that knwo its an amazing tape specifically for XPS. I didnt want to use normal contractor tape since after looking for reviews and testing most tapes peeled off after 1 year or so.

Well, my first serious heating bill is in. Granted last year in November we still didn't have the attic insulation at R60 however savings are at 50% or more.

I calculated last year on December/January during the winter spell and with attic already insulated at 4.5 BTUs/HSF ... Now I used my living space of around 1200 sq ft... however I am not sure if I should use the basement as well since we have as many ducts in the basement as upstairs even though it's unfinished.

This november is in.

740 HDD vs 670 last year - about 11% colder.

Therefore, we spent 19 therms this year vs 42 last year (last year our setbacks were also more agressive. Nowadays I don't keep the house colder than 60F because of... wife)

When calculating BTUs per HDD per sq ft should i do 2300 sq ft or just 1150? Not sure what to use ... we have 5 ducts downstairs so in essence it's a heated basement of sorts - even though we only have a very leaky cellar door. Good knows how much is leaving the house that way.

This year, our house has a heating need of 2.23 BTUs/HDD/sqf

If I include the basement, then it's 1.11 BTU/HDD/sqft

Both seem super low... The average new construction on a TIGHT house says its about 5 BTUs ... Although I tried making our house as tight as possible, this a 1950s house where nothing was done to walls nor sheahing ... Can the pros chime in, maybe I did the calculations wrong? But I think they are right ...

19 therms * 100,066 = 1 901 254 BTUs

Divide this by 740 HDDs = 2569 BTUs/HDD

Divide it by sq footage ...

Acording to EIA, a newer house from 2005, has an energy intensity (I guess that's the proper name of the calculations above) is 3.6 ...

Well...I am at worst case scenario 2.23 ... best case scenario (if I include basement as conditioned space at 1.11 !!! )

If we do the reverse for the full winter and make calculations of how much I am going to spend this winter...

2.23 as base load x sq footage x HDD per season

I come out at 150 therms (yes I know that the bigger the delta heat transfers faster so these are just rough estimates). This would compare to the 300 therms I used last year AFTER attic was already R60. So, I am assuming with these calcs, that insulating the basement PLUS rim joist can have an impact of almost 50%. Heck, Ill be happy with even 30%-40%. Which is crazy!

If indeed I end up with 150 therms for a 5900 HDD winter, that's like 140 dollars or so of heating costs!

My full consumption for the year would come out at around 190-200 therms (heating + base load). So about 180$ in NG ... I pay 17$ month for access so my bill would be 384 dollars per year where 204$ would be just Customer charge.

The customer charge would be enough to heat this house if I were to change heating to electricity by using mini splits. At 150 therms, that's about 4400 kWh. Using a minisplit with COP = 4 it means 1100 kwh of usage @ 9 cents per kWh .... = total heating costs of $100. A savings of 280-300$ per year.