4 Pitfalls of Spray Foam Insulation

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Spray foam insulation is great for the building envelope.

Spray foam insulation is a great product. Homes insulated with it can be some of the most efficient and comfortable homes built. I've been in plenty of these homes and can tell you that when spray foam is installed properly, they outperform 99% of fiberglass batt-insulated, stick-built homes. (I can also tell you that 73% of all statistics are made up on the spot, so please don't ask for documentation of that statistic.)

Spray foam comes in two flavors, open cell and closed cell, and provides both parts of the building envelope - the insulation and the air barrier. The building envelope should completely surround the conditioned space, and the insulation needs to be in contact with the air barrier. Since spray foam is both insulation and air barrier, proper alignment of insulation and air barrier is guaranteed.

What's not guaranteed, however, is that all spray foam homes will be efficient and comfortable. I've seen a number of houses with problems even though they're insulated with spray foam. In order of prevalence, here are the problems I've seen, with explanations following the list:

  1. Spray foam isn't thick enough.
  2. Spray foam installers missed some of the air leakage sites.
  3. Spray foam installers didn't understand the building envelope and sprayed either too little or too much.
  4. Spray foam contracts and pulls away from framing.

Spray foam isn't thick enough.

This is more common with closed cell foam, but it happens with open cell foam, too. Since closed cell foam has a higher R-value per inch, installers generally spray 2" in walls and 3" in rooflines to meet the energy code requirements of R-13 and R-19, respectively. (I'm not going to dive into the energy code here, but these numbers apply to many climate zones, the latter being allowed under the UA tradeoffs rule. See the Energy Nerd's blog on this topic if you want to argue.)

Open cell foam usually fills the framing cavity completely, so it's easy to tell if the installer has sprayed enough. Closed cell foam doesn't fill the cavity, so you've got to spot check in a bunch of places to make sure you don't get shorted.

The video below is from a house near Charleston, South Carolina that I visited recently, and you'll see that the homeowner in this case didn't get his money's worth. I knew immediately when I walked into the attic that something was wrong because it was hot up there. In a properly insulated spray foam attic, the temperature won't be much higher than the house temperature. 

The problem was that the installer was doing his first spray foam job ever, and the thickness of the insulation varied from zero (visible roof deck) to about 9". Unfortunately, good average thickness doesn't cut it. The coverage needs to be uniform because a lot of heat will go through the under-insulated areas. (See my article on flat or lumpy insulation performance.)

Spray foam installers missed some of the air leakage sites.

Once I got a call to look at a 10,000 square foot house that had spray foam throughout, but the owners had a serious problem in their first summer in the house. When I arrived, they took me to the master suite, where two towels were on the floor - to catch the rain falling off of the supply registers in the ceiling!

The problem was that the installers missed some areas at the soffit in the attic above the master bedroom, and gaps around the tray ceiling allowed the humid air into the room, where it naturally found the cold surface to condense on.

As this example illustrates, it's important to seal the envelope completely. One of spray foam's biggest selling points is its air-sealing ability, but it can't seal places where it's not sprayed. One of the nice things about using spray foam in new construction is that you can do a Blower Door test before the drywall goes in. Even better, you can test for leaks with a fog machine.

Spray foam installers didn't understand the building envelope and sprayed either too little or too much.

In complex houses, seeing exactly where the building envelope is can be a challenge. If the installer misses areas, it may or may not be an air leak, but it will definitely be a thermal bypass because of the lack of insulation. Every part of the building envelope must be insulated, or the home will have excess heat loss/gain.

Another problem I've seen is that the installer sprays extra foam because they haven't identified the location of the building envelope, the boundary between conditioned and unconditioned space. In the photo below, that wall with foam all over it has conditioned space on both sides. The homeowner paid extra and got nothing for it.

 Spray foam is wasted on partition walls.

Spray foam contracts and pulls away from framing.

I've seen this only once, and it was with closed cell foam, but I've heard of it happening with open cell foam, too. I don't know the details, but I've heard it could result from a bad batch of chemicals, improper mixing, or too high a temperature. Whatever the cause, it's not a good thing. The photo below shows how the spray foam pulled away from the studs. A little bit of uninsulated area like that adds up to a lot of heat loss/gain when the whole house has that problem, as it did here.

Spray foam pulled away from the framing in this house.

Conclusion

Don't assume that just because a home is insulated with spray foam that it's automatically a winner. Every product has its pitfalls, and spray foam is no exception. The good news, though, is that spray foam's problems are generally less frequent and easier to overcome with proper planning and follow through.

 

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Related Articles

Flat or Lumpy - How Would You Like Your Insulation?

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Comments

John
Jun 29 2010 - 2:29pm

Good article. How can I determine what the envelope is so I can do my own quality checks? Is that something the architect should articulate for me? Should I just figure it out on my own? Last question: How long does it take for foam to separate (last problem mentioned) if it's going to separate?

Sean @ SLS Construction
Jun 29 2010 - 3:23pm

John, I would suggest you bring in an Energy Auditor or Consultant before and after the work is completed. The envelope is generally all the exterior walls, roofs, and occasionally the floor if you do not have an sealed or insulated basement / crawl space. 
 
 
 
In the few cases I have seen - it was noticeable either that day or within a few days, especially if the temperature changes by 30 or more degrees between the day & night. 
 
 
 
Allison, I would like to add one item to your list - make sure you use the right foam for the right area. There are many area's that Open Cell foam should not be used without a vapor barrier or other methods being employed.

Allison Bailes
Jun 29 2010 - 3:53pm

Lisa, thanks for alerting me to Tom's article. I hadn't seen it yet, but apparently it's the latest in the string of articles that I think started here with the one I wrote about efficiency vs. conservation. 
 
(Instead of just pasting in the URL, you can actually link to the article using the appropriate html.)

Allison Bailes
Jun 29 2010 - 3:57pm

Great questions, John! Yes, Chris will make clear where the building envelope is in the plans he's developing for you. Also, as Sean said, the home energy rater who inspects and tests your house will make sure that the builder and insulator deal with it properly. 
 
Regarding time of separation, I don't recall how long it took on the house where I saw it, but I think it happens fairly quickly, as in hours.

Allison Bailes
Jun 29 2010 - 4:01pm

Sean, thanks for jumping in and answering John's questions. About choosing the right foam, I intentionally avoided the open cell vs. closed cell foam debate. I did this partly because it's worthy of an article all by itself, but mainly I didn't include it because, despite all the warnings the two sides issue about the other, I've never personally seen a problem caused by using open cell where they should've used closed cell or vice versa. I'm sure things like that happen; I just haven't seen it yet.

Ted Kidd
Jun 30 2010 - 12:34am

Nice thread!  
 
Also good to "wrap" the rafters. Framing is a significant bridge for significant surface area. Even 1/2 inch of foam stops a lot of thermal bridging.

Allison Bailes
Jun 30 2010 - 6:59am

Excellent point, Ted. As you can see in the floor photo and both roofs shown in this article, spraying foam over the joists/rafters isn't common practice with a lot of spray foam contractors. 
 
I've had an article on thermal bridging taking shape in my head for a while now, and I'll certainly mention this aspect of it.

Jamie Kaye
Jun 30 2010 - 8:27am

Good article Allison. 
 
The local foam installer that I used here in Hilton Head told me he looked for some peeling back of the foam. This was ensuring that it was at the perfect temperature which helped them maximize their yield (profit). I have open cell foam and it pulled away a little, and did so immediately (within minutes). They went back after they were done to any spots that pulled away too much and filled them with the touch up kit; they were looking for the top edge to roll just a little bit. 
 
Best, 
Jamie 
 
 
 

Allison Bailes
Jun 30 2010 - 10:00am

If your foam pulled away just a little bit, Jamie, and they were able to fix it with just a little bit of touching up, then it wasn't as bad as the house where I saw this problem. As the last photo above shows, it had pulled away significantly from the studs and rafters, and it was all over the house. This was closed cell foam, and interestingly, it didn't pull away from the horizontal framing members, just the vertical and sloped ones. They did some touch up, but that wasn't enough. I don't know how this one ended up getting resolved. I think maybe the contractor came back and sprayed cellulose on top of the foam.

Jax Spray Foam
Jul 6 2010 - 12:58am

Great article and thread here. There are plenty of case studies done at spray foam dot org's site.

Todd Cannady
Aug 9 2010 - 12:43pm

Allison, I was a student at southface last august when you were teaching with mike. I got your email and was reading the down falls of foam. I am a Insulating contractor and spray both foams. We just had our foam rep. up last week training some of our installers. 
 
The problem you saw with the closed cell foam pulling away like that is due to the heat of the foam was to hot. It was actually curing out and making foam before it could adhere to the wood. The installer wasn't reading his foam correctly. He should of stopped and turned down the heat on his hose temp. Also installers have to be aware that as the sun rises and the temp in attics rises the subtrates get hotter as well. This will cause the installer to adjust his heat when installing the foam as the temp changes thru out the day.  
 
With open cell if it draws away it means it is to hot as well,you can dial the temp back and you are making good foam again. With open cell you can go back and touch up those areas alot easier. 
 
In the case you have above the installer wasn't reading his foam. They must be trained to do that as they spray. Temps and conditions are constantly changing thru out the day. Either he wasn't properly trained or if he was,he wasn't doing his job! This is a serious problem with people jumping in to the foam business. A lot of homeowners and builders are looking the best price and end up with someone who doesn't know what they are doing. Hope this info helps. Foam insulation is a great product. It just has to be done right by someone who knows what they are doing.

Allison Bailes
Aug 9 2010 - 2:08pm

Todd, nice to hear from you! Hope you and Parker are doing well. 
 
Another guy I know who used to spray foam told me about the importance of having the foam at the correct temperature, too. He said that sometimes just letting the hose idle for a while causes the foam to overheat and pull away like that. 
 
I agree with you that foam is a great product. In fact, that was my first line in the article.

Allison Bailes
Aug 9 2010 - 2:14pm

Peter, sorry for the delay in responding to your comment. I guess those 2 hours of sleep I get each night are just too much. ;~) 
 
Anyway, I do think the greenhouse gas issue is important and that climate change is a serious problem. I believe another problem is going to trump climate change, however - peak oil.  
 
I loved Tom's article! I read it when it first came out.

Allison Bailes
Aug 10 2010 - 8:36am

OK, Peter, I finally went back and read Alex Wilson's article on what he perceives as a serious problem. I haven't seen the full report, but based on the summary he wrote on the Green Building Advisor website, I question the science. It seems to me that he's chosen the wrong metric and he's basing his conclusion on too many assumptions because he doesn't have enough data. You can see my comments at the end of his article.

Dennis Haskett
Aug 24 2010 - 2:01pm

Each of the four problem areas you cover are directly attributable to the installer, not spray foam. The title of your article is misleading. Properly trained and certified installers avoid every one of the situations you have covered.

Allison Bailes
Aug 24 2010 - 2:29pm

Thanks for your comment, Dennis. Perhaps you missed the first sentence of the article, though: "Spray foam insulation is a great product."  
 
I'm not condemning spray foam at all, and, in fact, I've defended the use of closed cell spray foam and extruded polystyrene foam board insulation in this blog. 
 
Yes, you're right that all of the problems mentioned above are related to the installer. I didn't try to hide that and even used the word 'installer' in two of the four headings. I can see how you'd think that the title is misleading, but in the end you can't separate spray foam insulation from its installation. Some people have the mistaken impression that if you get spray foam in your house, your home will outperform all others. My point here is that that's not true.

Dennis Haskett
Aug 24 2010 - 7:48pm

Thanks Allison ... Points well taken, however I must dissect 'but in the end you can't separate spray foam insulation from its installation' to some degree. 
 
 
 
I've done ratings and consultations for several contractors in the San Francisco Bay Area, and the difference in spray foam subs can be night and day! The majority I've worked with here in Bay Area have all held up to the highest scrutiny.  
 
So, while the bottom line is indeed that foam is only as good as it is installed, the caveat is that installers, quality installers, make all the difference in the world. 
 
Should you find yourself in the Bay Area any time soon, please drop me a line, and I can take you to some high quality installations, as well as enlighten you on the merits of open cell foam. 
 

Allison Bailes
Aug 24 2010 - 9:08pm

You've got no argument from me there, Dennis. Getting a good installer if you're going with spray foam is crucial. Many builders or homeowners don't know how to find one, however, and that's where third party inspections come in. Also, even good installers have bad days, but if someone comes in behind them with a measuring probe and a Blower Door, there will be fewer sub-par foam jobs.  
 
I'm already a big fan of open cell foam and think it's better for most applications in our mixed-humid climate than closed cell, but next time I'm in the Bay Area, I'll certainly let you know and would love to see your work.

Tina
Aug 31 2010 - 4:47pm

We have a 22 year old home located in southeastern georgia where the humidity is very high. In the past 2 weeks our floors have started buckling all over. We have a vented crawl space and the old insulation is drooping from moisture and the wood is wet. We are debating between the "encapulation" method or the spray foam method to repair this issue. Which would you recommend?

Jennifer
Jan 10 2011 - 8:54pm

Hello, thanks for the information. 
 
Are you able to share what you've learned about poly spray foam as it relates to health risks post application? 
 
We live in the Northeast and having trouble finding out if spraying closed cell poly foam in the crawlspace under our bedroom floor is a health benefit or health hazard.  
 
Some say the foam will act as a barrier from bad air in the crawl space (we already have an ezbreath 'air exchange' unit and plastic vapor barrier on the crawl space floor to help reduce basement and crawlspace humidity)  
 
Others (my law friends who work for NYC) say poly foam is not healthy to have under your room where you sleep. 'That is nasty stuff' they say. 
 
Any poly spray foam birth defects or other issues to be concerned with during pregnancy?  
 
Our home is a 1950's ranch sans wall insulation.  
 
Just some old R19 fiberglass in the attic and the around the pipes in the crawlspace.  
 
We are cold! 
 
Thank you kindly for your thoughts, Jennifer

Drew
Jan 15 2011 - 6:32am

Good article, but it seems like you can chalk up almost all of those problems to the experience level of whomever is spraying the foam. Spray foam isn't an inherently bad product, but it's pretty easy to botch if the hired company is inexperienced. Fiberglass may be foolproof to install, but then again it has a terrible R-Value compared to a good spray foam. People just need to get referrals and do their homework whenever they research a spray foam contractor.

Allison Bailes
Jan 15 2011 - 6:50am

Jennifer, I'm not an expert on the health effects of closed cell foam. A lot of people live in houses with closed cell foam and have no health problems from it, at least not short-term, acute problems. I do know of one person who had it removed from her crawl space because she was convinced it caused her dog to get sick, but I know only what she told me.  
 
If you're chemically sensitive, it's probably not a good idea to get it installed, but it's also not a good idea to breathe musty air from the crawl space either. In addition, your house and its contents are made of lots of materials that affect your indoor air quality. If you're really concerned about this, hire a company to test your air and tell you what you can do about it.

Allison Bailes
Jan 15 2011 - 7:05am

Drew, I've already addressed the first part of your comment in my response to Dennis Haskett's comment above. Yes, these are mainly installer issues, but as I said to Dennis, you can't separate spray foam insulation from its installation.    
   
Your comment about fiberglass is incorrect, on both counts. It's not foolproof to install, and its R-value per inch is pretty much the same as open cell spray foam - when it's installed correctly, which is almost never.

Sandi Kelley
Apr 3 2012 - 6:44pm

I have been looking to have closed cell insulation added through out my attic space. I cant seam to find a installed that wants to install no more than 2 inches, and thats not near my R-valve for South Carolina (Lake Greenwood)please send any advice that will help me to see what installer will perform the correct job. This is a expense that i can only afford to do once. Sandi

Steve
Apr 25 2012 - 7:55am

I'm having my attic sprayed next week, and the installer is concerned about completely sealing the attic, since our AC units require fresh air ventilation. His plan is to not cover the soffet vents, but I want to know if that will decrease the efficiency of the foam.  
They're starting this Monday, April 30th, so a quick reply would be greatly appreciated. Thanks.

Allison Bailes
Apr 25 2012 - 8:42am

Steve: If your spray foam installer leaves the vents open, he will be committing the 2nd of the 4 problems I described above. You will most likely have comfort and efficiency problems. You may well have condensation problems. You will be spending a lot of money on a product that likely won't perform as it should. Don't let him leave the vents open. If the installer you've chosen doesn't understand this, you may want to choose someone else. 
 
What do you mean by "our AC units require fresh air ventilation"? Fresh air doesn't come from the attic. If there's an atmospheric combustion appliance in the attic, such as an 80 AFUE furnace, then you shouldn't be encapsulating the attic anyway. If that's the case, you don't want spray foam on the roofline at all. You can either change out the furnace to a sealed combustion unit or do your insulating and air-sealing at the flat-ceiling level.

Dena Platis
Apr 26 2012 - 2:15pm

We are turning our roof into an unvented roof assembly by raising the roof and blowing in SPF. We are planning to leave the existing vapor barrier down but remove the fiberglass batting and then adding 6" of SPF in all the cavities, to completely seal and insulate the house. Should we have any concerns about doing it "upside down" and not spraying the foam directly to the underside/sheathing of the roof?

Steve
Apr 28 2012 - 10:04am

Thank you, Allison. We have a split system unit (actually 5) with the heat being propane. The foam guy said that it needed ventilation, so completely sealing the attic wouldn't be a good idea. It sounds like you are saying that the systems need to be vented out of the attic or replaced with some type of closed system. But I shouldn't bother spraying if the plan is to leave the soffet vents open. Is that correct?

Denise Hilberling
May 5 2012 - 1:36pm

I am building a house in Central Texas (Caldwell). Several builders are cautious about using foam insulation and/or a closed attic. I would like to use both. Here in Texas, heat and humidity (except for the past few years of drought) are a continuing problem. Which type of foam would be the best to use in our home, where should the vapor barrier be or should be use one at all, if we are using fans in the exterior walls to supply fresh air to the house, do we need a vented attic or will it cause more problems than it solve? I have printed out your article and the blogs to give to my contractors and architect, but I would really appreciate your comments on the products being used in my part of the US. 
 
 
 
D.Hilberling

Barbara Hoggan
May 13 2012 - 2:16am

I just had closed-cell insulation foam installed in my bathroom. The outside wall's foam is very uneven.  
 
1) Can the spray be reapplied to increase the shallow areas? 
 
2) If my spray company refuses to rectify the problem, will getting a building inspector help? 
 
3) The company said it's an R-value of only 15, but it has 'the effect of R-90.' What does that mean? Is that true?

Jim Smith
Jun 12 2012 - 2:54pm

We have a 1950's ranch in Atlanta and are interviewing foam contractors to spray open cell under the roof, with an "ankle wall" out towards the eaves to seal the attic. My wife and daughters are chemically sensitive, so I'm trying to figure out how to minimize the fumes coming into the house. Additionally, at least one contractor has offered (for > $900) to remove our existing rock wool & R-13 fibreglass from the attic floor to "increase cross-ventilation into the attic". Seems to me I can't both minimize fumes AND increase cross-ventilation. They also offered to spray a fire-retardant on for >$600. Would ventilation during installation help any or woud the retardant seal off the foam and help that way? Thanks...

steve
Aug 17 2012 - 9:08pm

once the foam is installed correctly, it is a inert plastic not much different than the foam cushions you sit on. there is not a health rick unless you have off ratio uncured foam that has not mixed properly. the foam is absolutely a health risk in its raw forms before it is mixed and cured. You should not be in the building without proper respirators and eye protection. The spray foam industry should be controlled and regulated by the same standards, testing and inspections that framing ,electrical and plumbing are. until that happens then you will have idiots with spray rigs ruining peoples homes and ruining the market for honest foam contractors that know how to price a job fairly and complete it correctly.

Debbie
Aug 20 2012 - 4:55pm

The guys who sprayed my attic were trained and certified, but I later found out, too late, that they had no experience and my attic was the first they'd ever sprayed. I was also never told to vacate my house for any length of time, and so I (and my pets) were in the house the day they sprayed and the entire time the off ratio foam was filling my home with horrendous vapors. The company kept telling me that it was a good job and I had nothing to worry about, even after I'd had 2 other experienced sprayers from 2 different companies visually examine the foam and confirm that large areas appeared to be off ratio. The 3rd sprayer from yet another company, was also outraged because the company who did my attic had failed to vacuum up all of the old cellulose insulation, and he also noticed areas where the foam was shrinking or pulling away, and this was not even 5 weeks after the spraying.  
 
 
 
This is in great contrast to my friend's experience. Her attic spaces were sprayed and the foam is actually pretty, and I was in her attic 6-7 days after it was sprayed and could hardly smell anything when I stuck my face up to the foam. And she did not have to clean up one speck of dust during or after the spraying. I got the name/number of the guy from her who managed her attic project, but between the time he did my house and the time he did her house, he was let go from the company who did her attic and hired by another company. He assured me everything would be the same, etc., etc., and I had no reason to believe anything had changed, but the sprayers who did my house later admitted they had never sprayed an attic before and I also found out that the foam used in my attic was from a different manufacturer. Neither my friend nor I had any idea this guy was with different company then, until the week after they filled my attic with off ratio foam, and my home with toxic vapors.  
 
 
 
I'm sitting in a hotel, 2 of my cats are in boarding, and we've all been exposed to off ratio foam vapors as well as the old celluose insulation dust that was spread through out my whole house when I let the same people come in to remove the off ratio foam (upon the advice of the manufacturer's rep). It's been an on going nightmare. 
 
 
 
But anyway, you probably won't want to publish my comment but people really should be aware of what can go wrong.

jim smith
Sep 6 2012 - 5:31pm

RE: my June 12 post...We went ahead and had the attic sprayed with a Soy-based product. Stayed in a hotel for 3 nites. Still smelled a little bad but that's gone away over time. I'm very glad we didn't use the other foam as even that much outgassing of a petrochemical could have sent my wife to the hospital. Unfortunately, the spray crew didn't speak English(at least not to me) and were kinda lazy, so they ended up spraying over some can fixtures from the kitchen below that were not insulation-contact rated. So I hired an electrician to come out, pull down the cans, pull out what he thought was an appropriate amount of foam to create a big enough air space and then re-install the cans. I billed the firm for the electrician plus an extra night we had to stay in the hotel and they paid, no questions asked. Guess they knew they had screwed up.  
 
I've just mentioned a couple of the multitude of screwups these folks committed but what's frustrating to me is that they were the top-rated firm on Angie's List for foam installation in this area. So yes, a nationally recognized certification process would be a boon to the good operators in this business.

Rick Lines
Sep 26 2012 - 2:03am

I currently have a blown in insulation that I would like to remove due to debris and rodent infestation.  
 
I would like to clean it out and switch to spray foam insulation. Is this possible? 
 
Since I currently have radiant barrier decking and roofline soffits set up for conventional insulation, are there specific areas that need to be retrofitted or altered to make a spray foam insulation project work? 
 
Thanks 
 
Rick

Jeff Sells
Oct 7 2012 - 2:06pm

We live in middle TN and had our house foamed last year. We noticed recently that some of the foam was shrinking and seperating from the floor joists. We contacted the installer and he informed us that the manufacturer had a problem with a batch of foam during the time frame we had our house sprayed. The contractor wasn't sure if we had the recalled batch installed in our house or not. He said he would check the batch numbers and let us know. He seems like a nice guy promising to do whatever it takes to fix any problems. Do we trust him, however, to be truthful about the batch number? Do we have any options for finding out the information ourselves? I inspected the entire crawl space of the house and noticed approximately (5) areas that were seperating and a couple areas where the foam didn't adhere to the block. Do I assume by it being so infrequent that it is nothing to be concerned about? My concern is the walls that are not capable of being visually inspected because of sheetrock.

Tim A.
Dec 27 2012 - 1:15pm

I employed a company to insulate my three story house in 2011. They started Insulating it in August of 2011...They said it would be a 3-4 day job. They installed it in 0.5"-8" lifts all in the same cavity, this left burned insulation and voids. They removed what they told me was the bad insulation and in the process cut many electrical wires. They fixed this. They then reinstalled too thick again in some spots and removed again. They then installed it for a 3rd time. The areas that I thought were good are now separating from the structural members leaving voids. As of October 2012, 1 year and 2 months of dealing with the contractor I told them I want proof that what has been installed carries a warranty or I want my money back and I will fix the problems myself. They have yet to provide me with this warranty. I have spent many hours in the house looking at what is bad and they need to fix. I am frustrated, 14 months of additional rent due to their negligence. I would like to know how I can get proof that the product carries the manufacturers lifetime warranty, or has it been installed improperly throughout the entire house. Desperately awaiting your response. 
Tim

Brenda
Feb 10 2014 - 9:44pm

I've heard that foam insulation blown into walls breaks down after some time into dust. Is that true? How long does it last?

Allison Bailes
Feb 10 2014 - 9:56pm

Brenda: That was true of the old foam in the '70s and '80s. It's not true anymore.

Brenda
Feb 11 2014 - 10:45am

Thanks Allison for your reply. How would you know if the foam broke down? It is sealed up inside the wall. How long is it supposed to last? Any figures on that?

justin
Feb 16 2014 - 7:40pm

After researching this, Im curious about a method called poor mans sprayfoam where foamboard is cut to size between studs and sprayfoamed around the perimeter. Aside from the labour doing the job yourself, the cost seems comparable, is one better than the other? What about the quality of the canned sprayfoam around the perimeter? When i see sprayfoam done, it is never a full depth of the studs, so you would get 2.5-3 inches in a 3.5" (2x4) wall. Any thoughts? 
Justin

Sean @ SLS
Feb 17 2014 - 6:49am

Justin: that method works great, the catch is making sure you but all the sheets together nice & tight & get them held in place.  
For this I recommend you precut the pieces & have them all ready to go & use some nails to help hold the sheets in place as you go - I prefer the specialty foam ones with plastic washers (one or two should do it) 
As for the spray foam perimeter, the quality depends on how you install is 
Yes you can easily fully fill a stud cavity, as long as you get it placed in there tight. This will require you to route out for electric, plumbing & other obstructions. For filling around these I prefer low-expanding

Brenda
Feb 17 2014 - 1:09pm

Can cement block crawl space walls be sprayed with foam insulation?

Allison Bailes
Feb 17 2014 - 1:20pm

Brenda: Yes, you can spray foam on concrete block walls. If the wall is below grade or in contact with the ground, you'll want to use closed cell spray foam.