Reuben's Home Inspection Blog


This year, I'm thankful for closed-cell foam insulation. Yeah, that's right.

Yes, you read that right.  I'm thankful for closed cell foam insulation.  Of course, I'm thankful for my family, health, and all that other jazz, but this is a blog about home inspections and home related topics, so I'm going to stay focused on that.  To fully explain why I'm so thankful for closed cell foam insulation, I first need to complain about my house a little bit.

My thirteen-year-old Maple Grove house has an unfinished basement with a walkout; this means about half of the basement walls have a poured concrete foundation, and the other half, the part that's above grade, has conventional 2x6 wood framing.  The foundation walls are insulated at the exterior with rigid foam; this is a great way to insulate a foundation, because it means that the concrete walls will be relatively warm, and the potential for condensation problems will be minimized.  If you want to read more about foundation insulation methods, click this link - foundation insulation.

Fiberglass insulationThe stud walls, on the other hand, were insulated the same way as 99.9% of the houses in Minnesota - with fiberglass batts.  Yuck.  While this is the standard way to insulate a wall, it's also probably the worst acceptable way to insulate a wall.  The photo at right gives a great example of how fiberglass batts are installed incorrectly all the time; just look at those gaps around the junction box.  I've already dedicated a blog to complaining about fiberglass batts, so enough on that topic.

In addition to having fiberglass batts for insulation, the vapor barrier in my basement was basically useless.  Here's how a vapor barrier is supposed to work: to prevent air from passing through the fiberglass insulation and creating moisture problems in the wall, a vapor barrier gets installed.  This consists of 6 mil polyethylene sheeting (aka 'poly', aka 'Visqueen') that has been made airtight; that means caulked, overlapped, sealed, taped, etc.  On a home built today, this will be done quite well.  On a house that's thirteen years old... no way.  The vapor barrier will probably be just about useless.

Unsealed vapor barriers create heat loss.  Just thirteen years ago, vapor barrier were never sealed. It was standard practice to just use a stapler to throw the poly on the walls and leave everything completely unsealed.  This practice allows for air to constantly circulate within the fiberglass insulation, creating a convective loop, which means a lot of heat gets lost through the walls.

I have my 'office' set up in my unfinished basement, so I spend a lot of time in the basement.  During the winter it gets very cold in my basement, despite the fact that I have 2x6 walls filled with fiberglass insulation.  Last winter I kept an electric space heater under my desk to keep my toes from turning in to icicles.

rim joist insulationFiberglass should never be used at rim spaces.  The rim space is the area between the floors of a house; this is an area where it's nearly impossible to install a proper vapor barrier.  Without a vapor barrier, condensation can occur at the rim space, creating mold growth or eventually rotting out the rim space.  This is why fiberglass insulation should never be used here.  On new homes, it never is.  The only type of insulation that gets used on new construction homes in Minnesota is closed cell spray foam insulation; we'll come back to that in a minute.

Unsealed vapor barriers can lead to mold growth.  When a vapor barrier isn't sealed and air is allowed to freely pass through the wall, what happens when warm, moist air hits a cold surface?  It condenses.  My basement stays relatively cool and dry throughout the year, so the vapor drive is really happening from the exterior during the summer.  The walkout part of my basement faces south, so this part of the house is where I have the greatest temperature differential between the exterior and interior of the walls.

During the summer, as humid outdoor air passes through my walls and hits the relatively cool vapor barrier, the moisture condenses.  This summer there was never enough moisture to actually drip down to the floor, but it was enough to leave drip marks in the insulation and allow mold to start growing between the insulation and the vapor barrier.  This wasn't major and I don't have mold allergies, so I wasn't too whipped up about this... but I couldn't allow this to continue.

Mold in fiberglass batts Mold in fiberglass batts 2

Enter closed-cell spray foam insulation.  To address all of the insulation, mold, and vapor barrier issues at the same time, I had the wood framed walls in my basement completely re-insulated about three weeks ago.  I had the vapor barriers removed, all of the fiberglass insulation removed, and closed cell foam sprayed in to the walls and rim spaces.

Foamed walls

I love it.  Closed cell foam acts as a perfect vapor barrier after 2", it doesn't allow for convection, and it has a much higher insulating value than fiberglass.  Now when I walk down to my basement, I don't feel a drastic change in temperature; my basement is only about two degrees cooler than the rest of my house.  I can sit here at the computer without a space heater, and I no longer freeze my toes off.  Life is good.

Having foam insulation sprayed in to the walls was expensive, but it was worth every penny.  Will I ever get a payback in energy savings?  I'm not sure.  I didn't even bother to check the numbers, because my main motivation for this project was comfort.  Saving energy and not having mold growing inside the wall cavities is just a bonus.

Happy Thanksgiving.

Reuben Saltzman, Structure Tech Home Inspections


Comment balloon 36 commentsReuben Saltzman • November 22 2011 05:58AM


My only problem with it is that we have no history to see how it, and the house, reacts when wet.  EXCEPTIONAL care must be taken not to let moisture inside the outer skin.  Especially when this is put in a roof.  I have yet to see it in the siding. But talk about a barrier!  It surely is.

Get your money back in savings?  Ha!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

The guy that installed the foam said he could show me the numbers that would prove a payback, but I wasn't interested.

A very good friend of mine grew up in a house that was insulated with closed-cell foam throughout, and the house was built by his dad in 1981.  The house had a ridiculously small furnace, and even then, it was probably oversized.  I inspected the house before it was sold this spring, and it's still performing very well, even after all this time.

Who knows, your concerns are valid, but I'm happy to be a tester.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) almost 7 years ago

You did an outstanding job on communicating the benefits of spray foam insulation.  I certainly stand behind the private decisions to imprve the air quality and comfortablitiy of a home, two very important aspects of the green movement. There is so much more to green than green :-)

You write very well and I enjoy your writing style. Thanks for sharing.

Posted by Cathy Criado, Making Real Estate Profitable (Criado Realty ) almost 7 years ago

Thank you Cathy!  I'm sitting in my basement right now, and I'm perfectly comfortable.  It's tough to put a price on that.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) almost 7 years ago

The house I inspected with Icynene had it in the attic.  You can't do both walls and attic space.  These folks chose attic.  It cost $80K.  NO way they will save that over the few years they will be in the house.  They won't save that if they are there 20 years! 

That guy can't possibly show you savings that large.  Remember, they need to be savings OVER AND ABOVE what would have been spent without the foam, which makes it less each month.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

$80K?  WHAT?  That is absolutely ridiculous.  Absurd.  The next time you know someone who needs spray foam insulation, have 'em call someone in Minnesota.  I'm sure any insulation contractor in Minnesota would be happy to drive out to VA with their equipment and crew, do it for half the price, and still make a ridiculous profit.

I can't even begin to describe how absurd $80k is.  Did you accidentally add the zero?  Here in Minnesota, you'll end up paying about $4/sq ft for closed-cell spray foam insulation in the attic, and about half that for walls.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) almost 7 years ago

Dunno, that's what they told me.  It was a huge house, though, finished third level, hip roof, with two, gabled furnace rooms stuck out on opposite sides.  For all I know it was $4/sq ft!

Here's the first post about it:

I was told the R-value was 48 all over.  I don't remember how thick that made it, but it looks real thick to me.  I thought that spending that kind of money was ridiculous too.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

Reuben, closed-cell foam insulation looks like the way to go, but even at $4/SF it still is expensive. Comfort means a lot so in that respect, I'm sure it was worth every penny.

Posted by Michael Setunsky, Your Commercial Real Estate Link to Northern VA almost 7 years ago

Reuben - I wish I have done that in my house when we built it. The cost justify the comfort and energy savings.

Posted by Mike Yeo (3:16 team REALTY) almost 7 years ago

Reuben great post not just on energy efficiency but on comfort and health. What about open cell foam, would that have worked as well? Or better yet when would you use open cell vs closed cell... Thanks

Posted by David Popoff, Realtor®,SRS, Green ~ Fairfield County, Ct (DMK Real Estate ) almost 7 years ago

Mike - it does not do well in hot and humid.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 7 years ago

I live in an old row house in the city of Richmond. I have been recently contemplating spray foam for my "attic". There is no insulation up there and no subfloor between the first and second floor. The air struggles to keep up in the summer (I get home from work and the ac will be running and the inside temp will be 80's) and in the winter my nose goes numb. I keep hearing good things and I'm leaning more and more into getting it done. Thanks for the post.


Posted by Tyler Rackley, (The 20/20 Team) almost 7 years ago

Reuben, just curious---what brand of foam did you use?

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) almost 7 years ago

My parents used this in their new home this year.  I'd like to put it in my attic.

Posted by Tammy Lankford,, Broker GA Lake Sinclair/Eatonton/Milledgeville (Lane Realty Eatonton, GA Lake Sinclair, Milledgeville, 706-485-9668) almost 7 years ago

Something like insulation I feel is overlooked by most home buyers, but it can have such a dramatic difference in the quality of life of a homeowner.  I definitely appreciate a well constructed home, I think it was money well spent.

Posted by Eileen Hsu, LICENSED REAL ESTATE SALESPERSON (Douglas Elliman Real Estate) almost 7 years ago

It is good to see progress in this arena...There are people that will drill holes and insert this stuff into any wall or structure right now. Then, they patch and it does make a difference too...interesting post thank you Mike

Posted by Richie Alan Naggar, agent & author (people first...then business Ran Right Realty ) almost 7 years ago

Reuben, I'm going to be finishing off my basement and was curious about foam. My concern is the payback, I don't believe I'll be in the house for very long. I'll have to do some kind of cost analysis I guess to see if it's worth it. Good information. Have a great day and Happy Thanksgiving!

Posted by Michael S. Bolton, MN Appraiser (Michael S. Bolton,Inc.) almost 7 years ago

I wish we had that in the lowest level of my home.  It's noticeably cooler than the rest of the house and not so comfortable in the winter.

Posted by Justin Dibbs, REALTOR® - Ashburn Virginia Homes for Sale (Pearson Smith Realty) almost 7 years ago

what a fantastic post!  I just put in one that was about some energy efficiency tips but this is even more detailed and I love that you put in photos!

Posted by Reba Haas, Team Reba, CDPE (Team Reba of RE/MAX Metro Eastside almost 7 years ago

Foam sounds good Always has, at least to me. Batting has never appealed to me. Here a lot of better builders use blown in cellulose. Acts a lot like the foam properties. And fire and termites don't like it, to boot.

Posted by Jon Quist, Tucson's BUYERS ONLY Realtor since 1996 (REALTY EXECUTIVES TUCSON ELITE) almost 7 years ago

Ahh...that is so touching Reuben. LOL. But I hear you, somethings we are thankful for are a little out of the norm.

Posted by Shar Sitter, Home Staging and Redesign Minneapolis/ St. Paul, M (Rooms With Style) almost 7 years ago

Jay - I remember that post!  I just went back and re-read my comments; funny, I just about said the exact same thing today :).  If that house was $4/ sq ft, that's one hell of a large house.

Michael - I think I ended up paying somewhere closer to $2 / sq ft for the walls - not nearly as much insulation is needed.

Mike - definitely.  I spend a lot of time in my basement, and it's great to not be cold.

David - open cell foam will never act as a vapor barrier, it has about half the insulating value, and it costs about the same amount of money.  The one benefit to open cell foam is that it works better for sound dampening.  The guy that did the foam at my house has a nice discussion of open cell vs closed cell foam here -

Tyler - the best thing to do for your attic would be to have about 2" of closed cell foam blown in, and then have it topped off with cellulose or fiberglass.  I wrote about this here -

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) almost 7 years ago

Charles - what brand of foam?  I have no idea.  I sent an email to my insulation guy to find out.  I'll get back to you on that.

Tammy - I bet they're happy with it.

Eileen - I agree.  My dad had foam insulation installed in his attic about a year ago, and it made a dramatic difference.  

Richie - I've heard of foam being installed from holes in walls, but I don't know of any contractors that offer it.  The 'traditional' foam needs to be applied in open air to allow it to cure properly.

Michael - If I were only going to be in my house for a couple of years, I probably wouldn't have made the investment either.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) almost 7 years ago

Justin - rigid foam boards work quite well too, but they're a lot more labor intensive.

Reba - thanks!

Jon - I'm a big fan of cellulose as well.  What do they use at the rim space in your area?

Shar - Lol, thanks :)  

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) almost 7 years ago

Reuben: A favorite of Mike Holmes also. Even though it might be more expensive, I think in the long run it's creates just a better environment which you've already experienced.  I really think that in this day & age it should be standard in home building.

Posted by Lyn Sims, Schaumburg IL Real Estate (RE/MAX Suburban) almost 7 years ago

Lyn - I totally agree.  It's already the standard for rim spaces in Minnesota, and it's getting to be more and more popular for other uses.  

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) almost 7 years ago

Interesting illustration and information, so what's a reasonable price to pay for the insulation? How is the cost calculated, etc? Thanks for your timely reply.

Posted by Kimo Jarrett, Pro Lifestyle Solutions (WikiWiki Realty) almost 7 years ago

We had a rep for a foam company speak at a recent S.T.A.R. class, and he said that the closed cell foam would add an extra 100 mph strength to the places applied. Even if that is exagerated a bit, that extra protection in the Hurricane prone areas like I live in is worth at least checking into. 

Posted by Travis "the SOLD man" Parker; Associate Broker, email: / cell: 334-494-7846 (Team Linda Simmons, Enterprise, AL 36330) almost 7 years ago

You have to wonder why blow in foam is so expensive when the basic materials are relatively cheap. I know the machines are costly but still would last a considerable time.

It seems to me a lot, if not most, of energy saving methods and devices are priced so that the sellers get the saving amount, not the buyers. I learned that is Cynicism-101.

In fairness, I should note Foamitgreen has a DIY kit for abount $1.10/sq.ft.,1/option,com_virtuemart/Itemid,1/

Posted by Marshall Brown, BSEE, CHI (Mid America Inspection Services, LLC) almost 7 years ago

Another great post! Love it. Thanks again.

Posted by Jayson Holland, Jay Holland ( almost 7 years ago

Am a huge fan of spray foam insulation and recommend it to anyone I chat with.  Here in AZ our ducts are in the attic. Our attics can rise to 150 degrees in the summer - no joke!  Imagine spraying the lid of the roof so that our attics only get to 10 degrees over the interior?!  What a huge benefit to HVAC systems from having to work so hard!  Great post!

Posted by Jan Green, HomeSmart Elite Group, REALTOR®, EcoBroker, GREEN (Value Added Service, 602-620-2699) almost 7 years ago

I agree about the closed cell vs. open. If I were to use foam it wouldn't be anything but closed. I recommend closed cell for rim joist for my energy audit customers. All builders I see here still use fiberglass. 

Posted by James Quarello, Connecticut Home Inspector (JRV Home Inspection Services, LLC) almost 7 years ago

Hi Reuben,  Excellent post and a great educationon insulation and the different types

Posted by Bob Miller, The Ocala Dream Team (Keller Williams Cornerstone Realty) almost 7 years ago

Reuben, great information.  I need to address leakage in my home envelope and this might be a way to insulate as well.

Posted by Chris Smith, South Simcoe, Caledon, King, Orangeville Real Esta (Re/Max Chay Realty Inc., Brokerage) almost 7 years ago

Interesting! Thanks for the info on the comparison. I didn't know that fiberglass batts were that problematic. It's good to know!

Posted by Sylvie Stuart, Home Buying, Home Selling and Investment - Flagsta (Realty One Group Mountain Desert 928-600-2765) almost 7 years ago

This is good stuff. If I was to be an insulating contractor, this would be my specialty.

Posted by Wayne B. Pruner, Tigard Oregon Homes for Sale, Realtor, GRI (Oregon First) over 6 years ago