Author Topic: Insulation of attic - Roxul or Cellulose? Sill Plate?  (Read 6945 times)

MrSal

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Insulation of attic - Roxul or Cellulose? Sill Plate?
« 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!




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
« Last Edit: December 12, 2017, 02:45:25 PM by MrSal »

Cromacster

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #1 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.
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MrSal

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #2 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!

MrSal

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #3 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 ...

Sun Hat

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #4 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.
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MrSal

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #5 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...

tardis

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #6 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.

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #7 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...
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Sun Hat

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #8 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.
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MrSal

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #9 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.

bacchi

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #10 on: November 18, 2017, 11:45:46 AM »
A layer of the 2x4 Roxul for fire protection + sound insulation and then blow in cellulose?

paddedhat

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #11 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.

MrSal

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #12 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!

Papa bear

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #13 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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GuitarStv

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #14 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.
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paddedhat

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #15 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.

MrSal

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #16 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.

GuitarStv

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #17 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.

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paddedhat

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #18 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.

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #19 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. 


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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.
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Re: Insulation of attic - Roxul or Cellulose?
« Reply #20 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.

MrSal

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #21 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

Prairie Stash

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #22 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.

MrSal

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #23 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
« Last Edit: December 01, 2017, 10:02:08 AM by MrSal »

MrSal

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #24 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
« Last Edit: December 03, 2017, 11:08:56 PM by MrSal »

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #25 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!
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Re: Insulation of attic - Roxul or Cellulose?
« Reply #26 on: December 04, 2017, 09:01:58 AM »
Wow, awesome work!
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Re: Insulation of attic - Roxul or Cellulose?
« Reply #27 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.

MrSal

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #28 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



Inside our little pig's pen aka insulation dam:



I think there were still about 20 bags left to blow at this point
« Last Edit: December 04, 2017, 10:17:26 AM by MrSal »

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #29 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?

MrSal

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #30 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 ...

MrSal

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #31 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 :)

MrSal

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #32 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

paddedhat

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #33 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)

MrSal

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #34 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...

paddedhat

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #35 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.

Syonyk

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #36 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.
My random project blog - ebikes, DIY, fans, and more: http://syonyk.blogspot.com

paddedhat

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #37 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.

MrSal

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Re: Insulation of attic - Roxul or Cellulose?
« Reply #38 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.




MrSal

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #39 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.

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #40 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.

MrSal

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #41 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

MrSal

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #42 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!!

Sun Hat

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #43 on: January 26, 2018, 08:59:07 AM »
Woot Woot! Congratulations on a job well done!
"You need a little bit of insanity to do great things." ~ Henry Rollins

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #44 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.

MrSal

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #45 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)...

Prairie Stash

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #46 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.

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #47 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.

MrSal

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #48 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 ...

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #49 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.