Author Topic: Insulation of attic - Roxul or Cellulose? Sill Plate?  (Read 20276 times)

LostGirl

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #50 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! 

MrSal

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #51 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.

zoochadookdook

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #52 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!

MrSal

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #53 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:



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.

zoochadookdook

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #54 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

DoNorth

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #55 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.

zoochadookdook

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #56 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.

DoNorth

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #57 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.

zoochadookdook

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #58 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 $$$$$.

DoNorth

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #59 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.

MrSal

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #60 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?

zolotiyeruki

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #61 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.

MrSal

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #62 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.
« Last Edit: November 22, 2018, 01:15:10 PM by MrSal »

frogstomp81

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #63 on: May 06, 2019, 03:12:33 AM »
Has anyone air-sealed their attic after blown-in fiberglass insulation has been put in on top of fiberglass batts? The blown-in fiberglass is insufficient as it is, but would just make the air-sealing more of a hassle than it would have been otherwise.

I'd like to air-seal and add cellulose, but not sure this is a viable option without removing all the blown in fiberglass first...

chops

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #64 on: May 09, 2019, 10:25:05 AM »
At our house, the previous homeowner had added blown-in rock wool on top of fiberglass batts.  Removing all of this to air seal is a very long and tedious process, but in true mustachian form, I did it.  Probably took me ~30 hours to complete for a 1200 sq foot attic. It just takes a very very long time to move the two different kinds of insulation and then air seal every gap/electrical wire hole/top plate.  It does make a big difference now that its complete, especially during the summer when superheated attic air can't sneak thru these gaps to heat the living space. 

I mentioned I did this to an amazing "DIY everything" neighbor of mine and he was shocked that I DIY'd this!  "I would have hired that out!" he said.  Hahaa! I actually called some insulation companies to figure out how much they would charge and they said they wouldn't ever even do this job because it is so long, and difficult to find each hole to air seal.  Kinda makes me feel badass, but it is also a difficult job.  My wife kinda thought I was crazier than usual on this one but does appreciate the finished result

 - Chops

zolotiyeruki

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #65 on: May 09, 2019, 11:46:52 AM »
Can you explain more of the process of moving all that insulation around?  What made it so time consuming?  Or was the air sealing the more time-consuming part?

chops

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #66 on: May 10, 2019, 08:21:49 AM »
It just took forever to sweep all the rockwool away, then lift up the fiberglass batts to find the cracks/holes.  then repeat X 1200 square feet.  I did it all myself so it definitely would go a lot faster with a couple people.

Spraying the air sealing foam was easy, kinda fun to fill those cracks and know you're air sealing your attic.  Make sure you wear a organic vapor filter mask when you spray.  Those foam sprays have nasty stuff in them (like Isocyanates) that you definitely don't want to breathe in. 

 - Chops

MrSal

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Re: Insulation of attic - Roxul or Cellulose? Sill Plate?
« Reply #67 on: May 11, 2019, 10:59:20 PM »
At our house, the previous homeowner had added blown-in rock wool on top of fiberglass batts.  Removing all of this to air seal is a very long and tedious process, but in true mustachian form, I did it.  Probably took me ~30 hours to complete for a 1200 sq foot attic. It just takes a very very long time to move the two different kinds of insulation and then air seal every gap/electrical wire hole/top plate.  It does make a big difference now that its complete, especially during the summer when superheated attic air can't sneak thru these gaps to heat the living space. 

I mentioned I did this to an amazing "DIY everything" neighbor of mine and he was shocked that I DIY'd this!  "I would have hired that out!" he said.  Hahaa! I actually called some insulation companies to figure out how much they would charge and they said they wouldn't ever even do this job because it is so long, and difficult to find each hole to air seal.  Kinda makes me feel badass, but it is also a difficult job.  My wife kinda thought I was crazier than usual on this one but does appreciate the finished result

 - Chops

I tried Diy the removal of the old fiberglass but it was a pain ... I gave up and went to Facebook market groups and posted help wanted. A guy ended up taking the gig and paid him about $100 .... Totally worth it especially to avoid the itchiness.