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Started By
Message
spray foam in attic
Posted on 7/18/23 at 8:56 am
Posted on 7/18/23 at 8:56 am
I've got a 1.5 story home with a high pitch roof without adequate ventilation. In the really hot spells so far this summer, my upstairs a/c is struggling to keep up and humidity stays pretty high. I've been considering some options to fix the problem.
One option is to increase ventilation (3 whirlybirds), add insulation backing boards to my upstairs walls on the attic side, add a radiant barrier, and blow in some more blown in fiberglass to increase r value.
The other option is to spray open cell in the rafters. I've gotten three estimates for open cell in the rafters, sealing ridge vents, and sealing soffit vents. Two of the companies are adamant that the existing blown in insulation must be removed. One company is adamant that it does not. The company arguing that it doesn't is owned by a guy who claims to be a building science professional. He claims this standard idea of removing existing insulation is totally unnecessary because all you're trying to do is create a separate thermal zone in the attic. I have no reason to doubt his credentials, but I just don't know enough to know what I don't know.
If I have to pay for removal of existing blown-in insulation, it may price me out of foam (it's like $1500-$2000 extra to remove), in which case I may have to go radiant barrier/ventilation/radiant barrier. Have any of y'all done any of the above before and do any of y'all have opinions or experiences to share?
One option is to increase ventilation (3 whirlybirds), add insulation backing boards to my upstairs walls on the attic side, add a radiant barrier, and blow in some more blown in fiberglass to increase r value.
The other option is to spray open cell in the rafters. I've gotten three estimates for open cell in the rafters, sealing ridge vents, and sealing soffit vents. Two of the companies are adamant that the existing blown in insulation must be removed. One company is adamant that it does not. The company arguing that it doesn't is owned by a guy who claims to be a building science professional. He claims this standard idea of removing existing insulation is totally unnecessary because all you're trying to do is create a separate thermal zone in the attic. I have no reason to doubt his credentials, but I just don't know enough to know what I don't know.
If I have to pay for removal of existing blown-in insulation, it may price me out of foam (it's like $1500-$2000 extra to remove), in which case I may have to go radiant barrier/ventilation/radiant barrier. Have any of y'all done any of the above before and do any of y'all have opinions or experiences to share?
9
Posted on 7/18/23 at 9:05 am to atom1505
My friend did that. At first he did the whirley birds but that did nothing. He struggled to keep the upstairs bonus room cold, even with the new 2 stage unit with all metal round ducts. The attic heat overcame the 2 inch insulation on all of the metal ducts, including the ones on the other 2 units in same attic.
Finally, he did what you described. They removed All of the existing insulation.
Now, it’s like a whole new world. All 3 units easily do their job. You can go in the attic at 2 pm on a July evening and hang out without excessive heat.
Finally, he did what you described. They removed All of the existing insulation.
Now, it’s like a whole new world. All 3 units easily do their job. You can go in the attic at 2 pm on a July evening and hang out without excessive heat.
Posted on 7/18/23 at 9:06 am to EF Hutton
Posting to follow. Who did your radiant barrier quote? I've been struggling to find someone who will install.
This post was edited on 7/18/23 at 9:07 am
Posted on 7/18/23 at 9:08 am to bluemoons
quote:
They removed All of the existing insulation.
This is my primary question. Is that necessary?
quote:
Who did your radiant barrier quote?
Green Jeans from Baton Rouge.
Posted on 7/18/23 at 9:16 am to atom1505
Just be careful with your roof warranty...if you care about that. Most manufacturers will void a roof warranty with spray foam.
Posted on 7/18/23 at 9:30 am to atom1505
what are your quotes for foam and open cell if you don't mind sharing?
my house is ~20yo with high pitch roof and it gets absurdly hot up there. in afternoon air can't keep up and i had to add a window unit to keep bonus room manageable in summer afternoon. also running pretty high humidity (usually around 60% in summer)
my house is ~20yo with high pitch roof and it gets absurdly hot up there. in afternoon air can't keep up and i had to add a window unit to keep bonus room manageable in summer afternoon. also running pretty high humidity (usually around 60% in summer)
Posted on 7/18/23 at 9:38 am to lsujro
They have run from $7000 to around $9000 without removal of existing insulation. My house has a high pitch roof as well and my upstairs area is about 800sqft living, but it's only 1.5 stories so the attic floor is also the downstairs ceiling in a lot of places. I'm not sure what my attic square footage is.
Posted on 7/18/23 at 9:58 am to atom1505
My home is being sprayed with open cell foam as I type. My guy told me that its an option to remove the existing insulation. If you do not remove the existing, it will take away some of the effect of the foam but not enough to warrant paying for the removal. So I did not remove the existing insulation.
Posted on 7/18/23 at 10:22 am to atom1505
your situation sounds exactly like mine with the bonus room. Ive been up in the attic looking around and weighing all the options. I havent gotten quotes but have a rough idea of what theyd be.
I think Ive decided to first try and seal all of the air leaks around canned lights, knee walls, and other penetrations so i can get the most out of my AC.
I was then going to install continuous soffit vents where i could. There are actually no soffit vents on the bonus room as of yet.
Then incrementally install radiant barrier. I would start on the East side as has the most accessible surface area. Then the South and finally West. I may do North as well. I just want to see the effects of doing it in stages but try to minimize issues with cell phone reception. The goal being just to lessen the heat transfer from the attic into the bonus room.
Radiant barrier is so cheap compared to the other options. Doing it myself, its pennies. It doesnt seem like theres much of a downside if done correctly.
I may also beef up the batt insulation on the bonus room walls in that are exposed in the attic. Also, I put some fancy light blocking blinds and light blocking curtain to keep the sun out during the day.
I could be way off on my strategy. If anyone sees an issue, let me know!
I think Ive decided to first try and seal all of the air leaks around canned lights, knee walls, and other penetrations so i can get the most out of my AC.
I was then going to install continuous soffit vents where i could. There are actually no soffit vents on the bonus room as of yet.
Then incrementally install radiant barrier. I would start on the East side as has the most accessible surface area. Then the South and finally West. I may do North as well. I just want to see the effects of doing it in stages but try to minimize issues with cell phone reception. The goal being just to lessen the heat transfer from the attic into the bonus room.
Radiant barrier is so cheap compared to the other options. Doing it myself, its pennies. It doesnt seem like theres much of a downside if done correctly.
I may also beef up the batt insulation on the bonus room walls in that are exposed in the attic. Also, I put some fancy light blocking blinds and light blocking curtain to keep the sun out during the day.
I could be way off on my strategy. If anyone sees an issue, let me know!
Posted on 7/18/23 at 10:54 am to atom1505
Do not spray the underside of your roof deck. It will void your roof warranty and kill the life your your roof.
Posted on 7/18/23 at 10:55 am to SmoothBox
Everything reputable that I have read/heard suggests that while this may be true:
This is not true:
quote:
void your roof warranty
This is not true:
quote:
kill the life your your roof
This post was edited on 7/18/23 at 10:56 am
Posted on 7/18/23 at 1:15 pm to atom1505
My parents did the spray foam ~7 years ago to eliminate moisture that was accumulating between their 1st and 2nd stories. All of the blown in insultation was removed prior to the spray foam. It was explained to me that you do this so that you slightly condition the now enclosed space in the attic.
They also had a roof replaced due to hail/hurricane damage, and had no problems getting it covered by insurance. I'm sure you are more likely to have a roof replaced due to storm damage than it fail within the life of the waranty in south LA.
For their issues, the spray foam solved the moisture problem, and has made the upstairs living area much more enjoyable in the summer.
They also had a roof replaced due to hail/hurricane damage, and had no problems getting it covered by insurance. I'm sure you are more likely to have a roof replaced due to storm damage than it fail within the life of the waranty in south LA.
For their issues, the spray foam solved the moisture problem, and has made the upstairs living area much more enjoyable in the summer.
Posted on 7/18/23 at 2:51 pm to SmoothBox
quote:
It will void your roof warranty
id love to know how many people ever collect on a roof warranty lmao.
Posted on 7/18/23 at 5:11 pm to atom1505
It 100% causes blistering on shingles, which deteriorates them and brings the life expectancy down significantly.
I can provide case studies from various shingle manufacturers and insurance companies proving this if you’d like.
I can provide case studies from various shingle manufacturers and insurance companies proving this if you’d like.
Posted on 7/18/23 at 8:49 pm to SmoothBox
Bought my house and the original builder spray foamed the attic. It’s as comfortable up there as anywhere in the house. That’s all I’ve got…
Posted on 7/18/23 at 9:30 pm to SmoothBox
quote:
It 100% causes blistering on shingles, which deteriorates them and brings the life expectancy down significantly.
I can provide case studies from various shingle manufacturers and insurance companies proving this if you’d like.
In the interest of knowledge, please do share. I'm not a roofer nor a spray foam expert. I do have spray foam in my attic from the initial build(I'm the second owner) and no obvious issues in my roof life(at 10 years currently). However, I own a older second home which had spray foam added at some point, and looks iffy on the installation. I will have to replace the roof sometime soon regardless.
Most interested if this is issues with closed cell spray foam (which I would expect) vs open cell spray foam, as well as other issues such as poor application of spray foam(adding to pre-existing construction vs new construction)
Posted on 7/18/23 at 9:38 pm to SmoothBox
quote:
It 100% causes blistering on shingles, which deteriorates them and brings the life expectancy down significantly
I don't have shingles. I'm not a fan of foam unless the entire roof deck is sealed as I don't want to chase a potential leak with that mess...
I'm in the middle of re doing a metal roof on an older house that has very little attic space with a low pitch. I have heard that radiant barrier can cause shingles to accumulate more heat. I'm not sure about the foam.
My neighbor has a spray foamed attic and has no shingle issues after about 10 years now.
Posted on 7/18/23 at 9:46 pm to GoAwayImBaitn
Certainteed is the only shingle manufacturer that doesn’t void a warranty on a spray foamed decked roof. They use to make spray foam so they claim to understand it better. Ventilation is a major component of spray foam. There has to be ZERO forms of ventilation through the decking (other than plumbing vents). No gable vents, ridge vents, box vents, turbines, or soffit vents. ZERO VENTING. If that’s the case, they will warranty it. And yes I just so have happened to go through a Certainteed training today haha.
Warranty’s are rarely used so take the risk if you really want to but it is a risk.
Warranty’s are rarely used so take the risk if you really want to but it is a risk.
Posted on 7/18/23 at 9:56 pm to couv1217
Shingle warranties have so many exclusions it's almost impossible to get any shingle company to honor the warranty
Posted on 7/18/23 at 10:38 pm to SmoothBox
quote:
t 100% causes blistering on shingles, which deteriorates them and brings the life expectancy down significantly. I can provide case studies from various shingle manufacturers and insurance companies proving this if you’d like
I’ve researched this issue extensively as well. My issue with a lot of the case studies you are referring to is twofold. First, a lot of those case studies were funded by shingle manufacturers. Secondly, for every study that suggests that spray foam causes shingle issues, there is another that says the opposite.
In my research I’ve figured out that there is a ton of misinformation out there about spray foam. I don’t want to hijack the thread or distract from OP’s original question though.
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