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Ask me anything about spray foam insulation

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Jr. Member
Jun 5, 2007
116 posts
9 upvotes
Peter,

One thing I don't really understand with framing 1/2" away from the wall is, doesn't that mean that every 16 inches for 8 foot lengths that the insulation factor is only 1/2" (R2.5) + the 4" width of the wood stud? As opposed to 2" of insulation (R10) + the wooden stud R-value (whatever that is)?

Is 1/2" of spray foam really enough behind all of the wooden vertical frames?

I get the idea that framing first ensures the frame is sealed into the wall so no gaps but we are also reducing the amount of insulation also, correct?

Also, if I intend of putting Roxul R15 batts in the wood frame, should the framing away from the wall be 2" if I want to put R10 (2") of spray foam? I'd assume so.
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Feb 3, 2014
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Mississauga
robmtl1 wrote:
Apr 21st, 2015 8:01 pm
Peter,

One thing I don't really understand with framing 1/2" away from the wall is, doesn't that mean that every 16 inches for 8 foot lengths that the insulation factor is only 1/2" (R2.5) + the 4" width of the wood stud? As opposed to 2" of insulation (R10) + the wooden stud R-value (whatever that is)?

Is 1/2" of spray foam really enough behind all of the wooden vertical frames?

I get the idea that framing first ensures the frame is sealed into the wall so no gaps but we are also reducing the amount of insulation also, correct?

Also, if I intend of putting Roxul R15 batts in the wood frame, should the framing away from the wall be 2" if I want to put R10 (2") of spray foam? I'd assume so.
Hi Rob,

R value is not a complete system of measure for how warm/cool a home will be. There are many factors that contribute to this as well, such as air tightness. Here’s a good read regarding the topic: http://cufca.ca/docs/R-Value%20Fairy%20Tale.pdf. It talks about other factors as well as how R value favors fibrous insulation.

If you’d like to look at R value alone, the 1/2" should give you an R3 and your standard 2x4 width wise should be almost R4 (3.5") so total R7. The real reason to do the half inch away from the wall is to continue the monolithic seal across your entire basement wall, which will tighten up the envelope and prevent any drafts.

If you are referring to the hybrid system of foam and want to put roxul over then foam, then yes, you will have to pull the studs 2" from the wall because you will not have enough room for the batt to fit. (2×4 = 3.5")

--
Peter
Owner, VIPFoam.com
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Feb 8, 2014
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PeterLN wrote:
Apr 24th, 2015 12:02 am
Hi Rob,

R value is not a complete system of measure for how warm/cool a home will be. There are many factors that contribute to this as well, such as air tightness. Here’s a good read regarding the topic: http://cufca.ca/docs/R-Value%20Fairy%20Tale.pdf. It talks about other factors as well as how R value favors fibrous insulation.

If you’d like to look at R value alone, the 1/2" should give you an R3 and your standard 2x4 width wise should be almost R4 (3.5") so total R7. The real reason to do the half inch away from the wall is to continue the monolithic seal across your entire basement wall, which will tighten up the envelope and prevent any drafts.

If you are referring to the hybrid system of foam and want to put roxul over then foam, then yes, you will have to pull the studs 2" from the wall because you will not have enough room for the batt to fit. (2×4 = 3.5")

--
Peter
Owner, VIPFoam.com
I'm sorry if this is spamming on your thread, but i want to make a few points i agree and disagree with you about.

R value is correct but has caveats.
R value is measured at specific temps, humidity and no air flow. All insulation has an R value, performance characteristics at different temps and airflow rating and these are all separate things that people like to clump together as R value but are not all the same thing.

To get maximum performance you need high R value, air tightness and good low/high temp performance.

Spray foam has the highest R value per inch but is susceptible to fire, improper installation (the mix gets messed up or is installed haphazardly), high cost, high GWP and has a few varieties to choose from that has quirks. For most applications you want closed cell spray foam, but you have to understand the assembly your using it in, the wood framing has to be able to dry in at least one direction and you have to make sure your not introducing additional problems, brick is a water reservoir cladding so wood behind it with closed cell spray foam behind the wood is a recipe for rot. Also too much building movement can cause cracks in the high density foam that allow water and air to flow through it. This is rare but does happen.

Fiberglass is a poor performer, it loses R value at lower temps, does not block airflow in the slightest (high density will somewhat) and performs poorly in fire. Its only virtue is its cheap. It also supports mold growth and should NEVER be used in a basement

Roxul is air permeable (but less so then fiberglass), will not burn, deters rodents, and is usually about 50% more expensive then fiberglass but much cheaper then spray foam.

Cellulose does not support mold, does not burn, is less air permeable then fiberglass, and is very cost effective. It can handle small water problems by absorbing then releasing the water (but bulk water problems can accelerate rot). It can also be installed incorrectly, you want high density cellulose in the walls but many companies use loose fill which will settle over time. Its R value increases slightly in colder temperatures (the opposite of fiberglass).

All insulations can suffer from thermal bridging where the wood framing is far less R value then the insulation, a 2x4 wall filled with R6/in spray foam will have a total wall R value of something like 10-15 because of the percentage of the wall framing which will have R value of about 5. Basement walls are typically best insulated with spray foam because it eliminates thermal bridging, is closed cell keeping water vapour out but needs to be covered by a fire rated coating, drywall or some companies offer a cementious coating (monokote).
lots of thermal bridging here
http://www.greenbuildingadvisor.com/sit ... %203_1.jpg


Interestingly some spray foam installers believe that since fiberglass performs poorly, they should get a free pass to do as badly in total assembly performance instead of demanding better total assembly performance
http://www.greenbuildingadvisor.com/blo ... ynene-says

More R value is always better, but you do hit diminishing returns, so you should meet minimum code, and exceed it by any amount you calculate is cost effective. For attics high R values are recommended because it is very cheap to add more insulation in a large horizontal empty space (making sure to airseal first)
http://www.greenbuildingadvisor.com/blo ... insulation

No matter what insulation you use you need to address air leakage and thermal bridging for proper performance.
The beatings will continue until morale improves
Newbie
Feb 17, 2013
58 posts
2 upvotes
Burlington
Hi everyone,

Just wanted to drop a quick note. I'm finishing my basement my self and was looking for someone to spray foam the basement. I had in a number of different companies and had my mind made up when I saw this thread and give Peter. Let me tell you I couldn't be more happy with the results. Even the city inspector commented on what a great job it was. Peter was knowledge, willing to take the time to careful review the job, offered suggestions to issues and very professional. He is just as helpful in person as he is here.

His prices wasn't the cheapest and it wasn't the most expense but the job was 1st rate in a home we plan on living in forever.

If your looking for spray foam around the west end of the GTA I would give Peter a call before you go with anyone else. If anyone has questions or wants to see pictures send me a PM.
I didn't get any deal or anything for writing this, check my posts this is not a bogus account.

Sean
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Mar 13, 2004
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Toronto, Ontario
Post pictures if you can. I'm sure other people including myself would like to see a bunch of pictures of the finished product.

Thanks
seanwilliamson22 wrote:
May 19th, 2015 2:24 pm
Hi everyone,

Just wanted to drop a quick note. I'm finishing my basement my self and was looking for someone to spray foam the basement. I had in a number of different companies and had my mind made up when I saw this thread and give Peter. Let me tell you I couldn't be more happy with the results. Even the city inspector commented on what a great job it was. Peter was knowledge, willing to take the time to careful review the job, offered suggestions to issues and very professional. He is just as helpful in person as he is here.

His prices wasn't the cheapest and it wasn't the most expense but the job was 1st rate in a home we plan on living in forever.

If your looking for spray foam around the west end of the GTA I would give Peter a call before you go with anyone else. If anyone has questions or wants to see pictures send me a PM.
I didn't get any deal or anything for writing this, check my posts this is not a bogus account.

Sean
0_o
<_<
>_>
Deal Addict
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Apr 19, 2006
1477 posts
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+1 for me also. Peter came out all the way to Scarberia today to spray my basement. Really nice guy, did a very good job. Someone who makes a post over a year ago, answers questions and sticks around still answering questions has my business. Will post pics if anyone wants but they're about the same as above. I didn't get a deal or anything either for posting this.
Member
Dec 7, 2006
446 posts
82 upvotes
Toronto
Peter, I am pretty certain that my house needs better insulation. The house is downtown Toronto, was built in the 1880s, and we estimate that most of it was gutted about 12 years ago. How big of a job is it to reinsulate? Would it involve removing all of the drywall?

Thanks in advance.
[OP]
Jr. Member
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Feb 3, 2014
134 posts
55 upvotes
Mississauga
pchan83 wrote:
Jun 2nd, 2015 10:01 pm
Peter, I am pretty certain that my house needs better insulation. The house is downtown Toronto, was built in the 1880s, and we estimate that most of it was gutted about 12 years ago. How big of a job is it to reinsulate? Would it involve removing all of the drywall?

Thanks in advance.
The optimal way to insulate the entire house would be proper 2lb closed cell foam. It makes sense if, for example, you are remodelling the home anyway. Otherwise, the cost of demolition and re-drywall'ing make this method hard to justify.

The other option is drill and fill with cellulose...with this method, the insulation will settle with time leaving gaps and if you have a multi-story home then your rim joist will not get insulated (area in between floors). Also, you have to keep in mind the drill and fill installers usually only trowel on some putty over the holes they drill...you will be left with the sanding and re-painting all your exterior walls.

Personally, I would look into stucco over 3" Styrofoam if you don't mind that look and if the historical society will allow you to (since the home was built in the 19th century). That way you will at least know that your home is encased with insulation.

--
Peter
Owner, VIPFoam.com
Deal Addict
Apr 22, 2014
2976 posts
429 upvotes
Oshawa, ON
I have a few options hoping people with homes where they've foamed the basement can chime in.

I'm getting my basement spray foamed (sometime before winter, I still need to gut the existing...).

I'm looking for suggestions re: framing and putting roxul in the studs.

I had originally intended to have the 2" 2lb sprayed in (3" in joists), then frame with 2x4 then put roxul in the studs. I'm aware I lose some sq footage here but I'm not concerned really.

One guy that quoted me said I should frame first about 1" from the wall and he'd spray in and forget the roxul. Since it's totally sealed, having only spray foam will be good enough and the basement will be plenty comfy.
Other guy I asked said do whatever I want... he doesn't care (probably not using him, other guy cares... I think, he did my attic and a bathroom pretty nicely).

Both guys said obviously it's easier for them if I frame after (bares walls easier to spray obv.) but the first guy is pretty sure the foam alone is good enough.

Anyway, is anyone living in a home where they only spray foamed 2" and didn't put any batts in the studs? Is it really good enough?
If it is good enough, can I just frame 2x3 1" out from the wall instead?
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Mar 13, 2004
8883 posts
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Toronto, Ontario
It depends on how much you spray and what the R-Value will be. Some info here - http://www.penta.ca/products/2lb-spray- ... sulations/

If you plan on spraying just 1 or 2 inches adding Roxul may not be a bad idea however if you are spraying 3-4 inches then you should not need any extra insulation.

I used to do spray foaming & for the sprayer it was always easier if no studs were up. However because the walls are usually not straight and we may spray a little extra in 1 section vs another area on the wall so you will loose a little extra space because of this. Also keep in mind if you frame before you are only getting 1" spray foam behind the 2x4 studding. So you may even want to bring it out 1 1/2inch when studding to get more behind there so you get more of your moneys worth.



eldeejay wrote:
Jul 23rd, 2015 8:44 am
I have a few options hoping people with homes where they've foamed the basement can chime in.

I'm getting my basement spray foamed (sometime before winter, I still need to gut the existing...).

I'm looking for suggestions re: framing and putting roxul in the studs.

I had originally intended to have the 2" 2lb sprayed in (3" in joists), then frame with 2x4 then put roxul in the studs. I'm aware I lose some sq footage here but I'm not concerned really.

One guy that quoted me said I should frame first about 1" from the wall and he'd spray in and forget the roxul. Since it's totally sealed, having only spray foam will be good enough and the basement will be plenty comfy.
Other guy I asked said do whatever I want... he doesn't care (probably not using him, other guy cares... I think, he did my attic and a bathroom pretty nicely).

Both guys said obviously it's easier for them if I frame after (bares walls easier to spray obv.) but the first guy is pretty sure the foam alone is good enough.

Anyway, is anyone living in a home where they only spray foamed 2" and didn't put any batts in the studs? Is it really good enough?
If it is good enough, can I just frame 2x3 1" out from the wall instead?
0_o
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>_>
Deal Addict
Apr 22, 2014
2976 posts
429 upvotes
Oshawa, ON
Quote is walls to R12 for vapor barrier and joists to R20. I took that to mean 2"+ and 3.5"+ respectively.
I'm aware it won't be as thick behind studs.
Just wondering if anyone has skipped the Roxul in this scenario and still find their basement drastically improved and saving on Enbridge bills and all that?
The explanation was that even at only R12 on the walls, it will be nice because it forms such a good seal.
sickcars wrote:
Jul 23rd, 2015 8:58 am
It depends on how much you spray and what the R-Value will be. Some info here - http://www.penta.ca/products/2lb-spray- ... sulations/

If you plan on spraying just 1 or 2 inches adding Roxul may not be a bad idea however if you are spraying 3-4 inches then you should not need any extra insulation.

I used to do spray foaming & for the sprayer it was always easier if no studs were up. However because the walls are usually not straight and we may spray a little extra in 1 section vs another area on the wall so you will loose a little extra space because of this. Also keep in mind if you frame before you are only getting 1" spray foam behind the 2x4 studding. So you may even want to bring it out 1 1/2inch when studding to get more behind there so you get more of your moneys worth.
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Feb 8, 2014
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eldeejay wrote:
Jul 23rd, 2015 9:12 am
Quote is walls to R12 for vapor barrier and joists to R20. I took that to mean 2"+ and 3.5"+ respectively.
I'm aware it won't be as thick behind studs.
Just wondering if anyone has skipped the Roxul in this scenario and still find their basement drastically improved and saving on Enbridge bills and all that?
The explanation was that even at only R12 on the walls, it will be nice because it forms such a good seal.
I would go with R20 minimum, it gives you good insulation but is not overboard. Spray foam is the best way to insulate the basement walls because its air blocking, preventing moisture laden air from contacting the walls and condensing. I don't like the wall 1" from the concrete and insulating, it causes a type of thermal bridging, R6 is likely not enough to keep the area over the dew point which is one feature of thicker insulation, so i would get the foam before building the wall if you decide to go that route. If your not making it a living space then consider getting monokote sprayed over the foam instead of studs/drywall, not every company does it, but it eliminates wall building material and labour. From what i understand the finished product will look like stucco.
Its rare but spray foam installation can go badly (so choose the installer very carefully)
http://www.greenbuildingadvisor.com/blo ... r-problems

BTW your local gas utility may offer insulation incentives so do look into them, saves you money
The beatings will continue until morale improves
Newbie
May 8, 2008
38 posts
16 upvotes
Toronto
I just removed raccoon-infested fiberglass batts from our attic with a brand new roof with Maximum Ventilation exhausts. I was originally planning to just do the standard R50 fiberglass blow-in and soffit baffles. However, I discovered that in this 1960's back-split, the roof is quite shallow and rests directly on the double brick wall so there is only 3-4" clearance for soffit venting, leaving only 1-2" left for insulation under the baffles around the perimeter. This seems like a recipe for cold spots.

Some options:
1. Install the baffles, spray closed cell foam just around perimeter under them and loose fill the rest.
2. Plug the soffits, loose fill everything, and add intake vents to the roof.
3. Forget about intake venting and just spray foam the entire attic with 2", topped off with loose fill to bring it up to R50.

I am guessing #3 is going to be the preferred option here (based on how often people are quoting greenbuildingadvisor.com and the fact that this is a spray-foam thread), but trying to be open minded and cost-conscious, are the alternatives even worth considering?
[OP]
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Feb 3, 2014
134 posts
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Mississauga
Proo wrote:
Oct 7th, 2015 11:36 pm
I just removed raccoon-infested fiberglass batts from our attic with a brand new roof with Maximum Ventilation exhausts. I was originally planning to just do the standard R50 fiberglass blow-in and soffit baffles. However, I discovered that in this 1960's back-split, the roof is quite shallow and rests directly on the double brick wall so there is only 3-4" clearance for soffit venting, leaving only 1-2" left for insulation under the baffles around the perimeter. This seems like a recipe for cold spots.

Some options:
1. Install the baffles, spray closed cell foam just around perimeter under them and loose fill the rest.
2. Plug the soffits, loose fill everything, and add intake vents to the roof.
3. Forget about intake venting and just spray foam the entire attic with 2", topped off with loose fill to bring it up to R50.

I am guessing #3 is going to be the preferred option here (based on how often people are quoting greenbuildingadvisor.com and the fact that this is a spray-foam thread), but trying to be open minded and cost-conscious, are the alternatives even worth considering?
You are correct. Insulating a low slope attic is very tricky. Fiberglass at 1" to 2" may be at best an R4 value and can lead to ice damming (heat loss) if not vented properly. Unfortunately this is the case with older houses where building envelope science was not as important as it is today. Today's construction techniques are better but can be improved. For example, thermal bridging (wood studs/joists).

Now, the ultimate solution would be to have the entire attic sprayed so that it is your initial seal with foam and then have a R40 blown on top. This process is quite expensive because you also have to hire someone to properly vacuum out the attic first. Spraying the perimeter only may save you some money, but it will still be a costly process because it is very labour intensive to try and spray in such a tight area. Form what is sounds like to me is that you have a 3/12 pitch on your roof. For an installer to install foam, he would need to be laying down flat on a piece of plywood with his arm sticking out as far as possible and hoping for the best. Please keep in mind that the optimal result when spraying foam is when the spray foam gun is perpendicular to the substrate.

I would NOT omit using the vents in your case because two inches of foam would not be enough. 4" of foam plus blown would work better, but then you can have an installer fail or get lazy/greedy and install the foam too thick too fast. 2lb closed cell foam is supposed to be installed in layers no more then 2" at a time, Ideally go around the area twice to allow the first layer of foam a chance to cool because an attic is a heat trap (please note my favorite episode of CBC Marketplace: https://www.youtube.com/watch?v=0Hh5MYv7lWc - the issue is always doing the job CORRECTLY).

The last thing you mentioned was being cost conscious. Hiring someone trust worthy to do this job will not be easy, let alone for a low price. If you are up for the challenge you can try to do the perimeter work yourself with a DIY kit of foam. The benefit is the cost, minimal heat gets generated, easy to move around (as oppose to being fully suited up pulling heavy foam hoses, spray as thick as you want (1.5lb density instead of 2lb) and the best benefit is that you know you sealed up the entire area and not taking someones word. There are certain things you should be mindful of NOT doing with a DIY kit, and I can expand on those if you'd like and this sounds like a good option for you. Let me know.

--
Peter
Owner, VIPFoam.com

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