This forum is a place for me to share my experience with foam insulation with you, the public. I've built a spray foam insulation company in the past and I'm very passionate about the benefits of foam insulation. What I want to get across more than anything is that foam insulation is, hands down, the best energy efficiency upgrade you can make. Double paned windows are good. Solar is good. Wind turbines are good. Nothing compares to polyurethane spray foam insulation, PERIOD! Solar isn't currently economical and isn't reliable. Wind turbines aren't currently economical and aren't reliable. Polyurethane spray foam insulation is a sound barrier, wind barrier, doesn't decompose in the wall, significantly reduces dust, pollens and allergens in the home and, most importantly, you get what you pay for.
There are so many things to teach you about spray foam insulation, we will tackle a new topic each month. I'm sure the discussions will fast forward us through the list of issues but we will still work our way through a number of issues pertaining to spray foam insulation.
I will not promote a particular spray foam contractor unless you contact me individually. However, I will offer my opinion on actual spray foam manufacturers.
Take what you want from this blog, but understand that I offer this as a service to help everyone learn about the many benefits of spray foam insulation. Some of the topics I intend to cover include:
The benefits of spray foam insulation.
The cost of spray foam insulation.
The drawbacks of spray foam insulation.
How does spray foam insulation impact the construction schedule?
What is wrong with other insulation products?
Which foam manufacturer should I choose?
The installation of spray foam insulation.
Thanks for stopping by and I look forward to the discussion.
-James
16 comments:
Hey James - thanks for the information! I am sold on the benefits of the spray foam insulation and plan to use it in the construction of my new home (hopefully breaking ground here in a few weeks - spray foam insulation is in the budget & plans). My only question/concern at this time is, What happens if you have a leak in your roof? Eventually my new roof with 35 year shingles will leak. Typically a leak is easy to detect by the big water stain ruining the sheet rock on the ceiling. With the roof deck sealed away by foam, where does the water go? Will it pool up between the decking and insulation? Run down to the wall? Will it cause the foam to break free from the decking? Will it seep through and show up like a traditional leak? It would be great if you could shed some light and experience on this concern. Many thanks!!
HillRaiser, a great question I get all the time.
When the roof leaks, the water will pass through the foam vertically and drop to the sheetrock ceiling. It will not get trapped between the foam and the roof decking UNLESS you use 2 pound, closed-cell foam. Don't do it. Use 1/2 pound, open-cell spray foam, specifically because it allows the water to pass through.
So, when you see the water on your ceiling, look above the water and remove the foam from the deck. Repair the roof leak and buy a small kit of spray foam online for a few hundred dollars and patch the foam. Voila.
James, I am planning to biuild a Southwestern adobe-style (spray concrete exterior wall finish and trowelled-on clay product interion side) 2 story house with flat roof in the New York State US. How will spray foam open or closed cell work for underside of roof, walls for this project? Is clay finish enough ignition barrier or do I still need drywall and does foam off-gas toxic fumes if it burns? Will clay/concrete stick to it? Thanks Carol
Underside of the roofdeck.
Carol, I always recommend using open-cell foam on the underside of roof decks because it allows water from roof leaks to pass through and make the location of the roof leak known. If anyone disputes this, get sample pieces of open-cell and closed-cell foam, set them on a flat surface and place water on them. See how long it takes for the water to pass through the samples. If you use, closed cell foam and have a roof leak, the roof deck will probably rot out before you ever knew you had a roof leak because the water gets trapped on top of the closed-cell foam and soaks the wood.
Another benefit of open-cell foam is it's soft, like shortcake. If you ever wanted to add a skylight, you would simply tear out the open-cell foam at the location. Closed-cell foam is rigid and would take a saw of some sort to remove. I've worked with both foams and we always said "don't spray the closed-cell where you don't want it" because it's a pain in the butt to remove.
Walls
I typically recommend open-cell foam in the walls because of the sound attenuation characteristics and the $/R-value data. Closed-cell foam is more efficient in how high the R-value is for a lesser thickness. However, if you analyze the dollars spent per R-value achieved, open-cell foam is more economical. Moreover, open-cell foam absorbs sound much more effectively than closed-cell foam, providing for a quieter environment.
The only time I see closed-cell foam in the walls is when it's used on the exterior of house or hotel up north or when it's used in the walls of a wine cellar, which have unusual temperature and humidity points.
Ignition Barrier
Depending on the ignition barrier rating of your interior facing (ask the contractor for manufacturer tech data), I suspect the clay product is going to be sufficient. Make sure you call your building code officials and have them review your tech data. This is the one instance I don't recommend to ask for forgiveness instead of permission. They'll bust you on it and make you redo it.
Toxic Fumes if burned?
If the foam is on fire, especially in your house, you have bigger problems than toxic off-gassing. Technically, any exhaust from a fire is toxic so there's no additional risk presented by the foam. An interesting aspect of the foam is that if it catches on fire and the heat source is removed, the foam will snuff the fire out. I've seen picture of a house that was struck by lightening and the only thing that kept the house from burning down was that the foam on the roof deck snuffed out the fire. If the foam is burning overhead, it will not drip down on inhabitants or firefighters, which was a huge concern back when foam insulation was being formulated.
Clay/concrete stick to it?
Clay and concrete will stick to closed-cell foam better because it's rigid, but I do not recommend applying those finished surfaces directly to the foam. Neither will stick to open-cell foam, as it's not rigid enough to use as a base. Technically, it IS foam and will give and/or dimple more readily than sheetrock, for example. You can push a dimple into closed-cell foam with a stiff finger, which you can't do to sheetrock nearly as easily.
Carol, I hope all of this helps. If you need more help or clarification, please let me know.
-James
James
We have a ten year old house and are exploring using foam in
The attic between the rafters. First question, thickness of the foam be? We have received quotes with thickness of 3,5,and 6..
Second question can they spray the foam within the exising walls. Will it blow 0Ut the existing Sheetrock.
Third question what's the best way to insulate a room over the garage with limited space between ceiling and rafters. And do we
We have to rip out all the Sheetrock on our garage ceiling (floor of the bonus room)?
Thanks
Zech
North Carolina
Zech,
I believe around 90% of the insulation qualities of the foam are achieved in the first three inches, so I would stay around 3, 4 or 5". Beyond that, you're only additional benefit is the sound attenuation, which doesn't really apply here.
This is a loaded question. Someone makes a "low rise" foam that you can hose into the wall and it expands slow enough that it won't blow the sheetrock out. The only problem is that you're fixing holes IN EVERY CAVITY in your wall (every 12 or 18", depending on your stud spacing), assuming you want foam in every cavity, which you should. Now, if you're talking about using the typical foam application, like what would be used for your rafters, that is "high rise" foam (Icynene/Demilec) and it expands so much and so fast that it will ruin your wall. Don't think that you can just push the drywall back against the studs and add screws. As we say in Texas....it ain't happenin'. This is the most frustrating "lost opportunity" with foam and older houses.
The best way to insulate a room over the garage with limited space /b/ ceiling and rafters......is to take down the sheetrock. A two car garage is roughly 400SF and shouldn't cost too much to replace, especially if you do the demo yourself. If you don't go all the way and remove the drywall garage ceiling, the quality/coverage can be so poor that it's not worth it. If you think of cutting "windows" into the drywall ceiling every 5 or ten feet and "shooting both ways", you end up spending close to what you would have spent on all new drywall, just to patch your "windows" and the quality would still be lacking. Again, remember, you'd have to do that IN EVERY CAVITY.
Bottom line is it's worth it to do it right. Spraying this floor completely stops the heat transfer (and a good bit of the noise) from the garage.
I hope this helps you, Zech.
-James
James, let me run this scenario by you and see what you think. We are in the process of building a home. Roughly 2200 Sq. ft. on the main floor and equal in the basement. 10ft ceilings upstairs and 9 down. I was thinking about not foaming the roof deck, but having the contractor spray 1" of closed cell on top of the ceiling to seal and then blowing cellulose insulation on top of the foam to achieve the R value. What are your thoughts?
Good afternoon, Doug.
That's not a bad idea but I think you might spend the money more wisely. I'll say two things:
1. Don't forget the walls.
2. Analyze the Per R cost.
Don't for get the walls. I think that making sure your walls are air tight and not leaking conditioned air to the outside is a bigger opportunity. Trading conditioned air for unconditioned air is much more detrimental than having hot air leak in from the attic with (main point) no wind "forcing the issue". Leaks in your walls are exascerbated by wind pushing the air in or sucking it out.
Analyze the Per R cost. In all of my analysis, I learned that PER R, open cell was cheaper and the main benefit (air seal) is achieved with either. Find out what a contractor will charge you for one board foot of open cell and one board foot of closed cell. A board foot is 12" x 12" x 1" thick.
In Houston, if we're charging $0.35/board foot of open cell (with an R-value of 3.81/inch) and $1/board foot of closed cell (with an R-value of 7/inch), that translates into ($0.35/3.81)= $0.09/R for open cell and ($1/7) = $0.14/R for closed cell. Why not just use a few inches of open cell for the same money and use your cellulose (Hack, Cough) on top of that to get to the R-value code requirement. You'll save money and not have the hassle of removing the closed cell for some future change like pulling a new wire or raising a ceiling or something. That stuff is a bear to work with.
All that being said, I've heard much, much worse ideas.
Good luck, Doug.
-James
James,
I have a raised house in New Orleans with a 3 foot high crawlspace. The crawlspace is covered by plastic sheeting. Currently the floor is insulated from below by fiberglass batts. The interior finished floor is oak strips and during the summer months we have been having a cupping problem with the floor, with some localized buckling. My research tells me that fiberglass is not the best choice for floor insulation above a crawlspace and can cause numerous problems. I understand your position regarding the use of open cell spray foam insulation – among its top benefits is stopping air infiltration. Humid air will be stopped before it can contact my wood floor and cause it to swell. But open cell foam is not a vapor barrier – closed cell foam is. Should I be concerned about vapor drive thru the open cell foam into the floor? Or is that component negligible compared to the air infiltration? If I use open cell foam for this application, do I also need a vapor barrier?
An article in Buildingscience.com (http://www.buildingscience.com/documents/insights/bsi-009-new-light-in-crawlspaces/?searchterm=crawlspaces) by Joseph Lstiburek recommends using closed cell foam to eliminate air infiltration and vapor drive. My contractor is doing his own research and may not have results for a while. What are your thoughts on this?
Thanks,
Lionel
Lionel, you are 100% correct! I am not an "open cell only" advocate, by any means. I always say that open cell and closed cell foam are perfect for very different applications. This is one of the two most obvious instances when closed cell is the better choice.
Absolutely, put closed cell on the underside of your home. Open cell works on some crawlspaces when the moisture is less of an issue. Get the fiberglass out as fast as you can. It's junk, it causes problems with wood flooring and it is a perfect place for rats and cats to nest.
Joe Lstiburek is the master of all things foam, and building science, for that matter. He's right and you're right.
The money you spend will be worth it.
Good luck, Lionel.
-James
does using opencell foam in your rafters void the warrenty of your shingles. i have been told it would
I am in the mountains of Colorado and am having trouble in my attic. I am getting condensation because of the hvac that is in the attic. It has caused a lot of damage to the lower levels. We've had suggestions to create a warm attic by using the spray foam insulation to the underside of the roof deck. Is that the best way to deal with the problem? The house is around 3200 sq. ft.- what should the cost be? I don't know how many board feet are in the attic.
Thanks
Iris
James, I'm a contractor in N.C. building a house for my family and me. I'm torn between batt and spray insulation. I understand what you have said in this forum about open cell for roof application, but am lost on exterior wall apps. Will open cell still seal out drafts or should I go with closed cell for the walls? As you've stated, the closed cell being more rigid, it poses problems for later retrofitting things into the walls as well as repairs down the road for crawl space installations if components are incapsulated in the foam.
Good afternoon, George. I'm so sorry for the delayed response. Hopefully, you haven't built a new house yet.
The answer to your question is NO, it will not void your warranty. The major shingle manufacturers have come out in writing and stated that foam insulation on the underside of roof decking will not void their warranty.
Even they see the future coming straight at them and it's been scientifically proven that the color of shingle has a more profound impact on the life of the shingle than having foam underneath it.
Anonymous in the mountains of Colorado, I would make sure you seal the attic (meaning no soffit or ridge vents), vent your gas heater (if you have one) and make the attic a semi-conditioned space by removing all of your insulation on the attic floor or by just letting it be. The conditioned air in the house should leak up into the attic and surround your HVAC equipment with air much closer to the temp in the equipment. Condensation forms with you have hot equipment and cool temps or cool equipment and hot temps. If you close the attic from outside air, the attic temp much more closely matches the temp of the air the equipment is providing.
Hope that helps.
Anonymous contractor in N.C., don't touch batt insulation. No need to be lost on wall applications. Open cell DOES seal out drafts....that's one of the main benefits.
Closed cell is for specific applications and this is not one of them.
Open cell is what I would do if I were you....and keep in mind, I sold and sprayed both, so I have no dog in that fight.
Good luck.
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