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

Home Inspector with Structure Tech Home Inspections

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.


Re-Blogged 3 times:

Re-Blogged By Re-Blogged At
  1. Russell Proefrock 11/23/2011 03:35 AM
  2. Dan Edward Phillips 11/28/2011 01:55 AM
  3. Dan Edward Phillips 12/11/2011 08:10 PM
ActiveRain Community
Minnesota Hennepin County Maple Grove
Minnesota Real Estate Investor Group
Home Inspector's Corner
Minnesota Real Estate
Best Practices
basement insulation
problems with fiberglass insulation
closed cell foam insulation foam insulation
how to insulate basement walls

Post a Comment
Spam prevention
Spam prevention
Show All Comments
Michael S. Bolton
Michael S. Bolton,Inc. - Zimmerman, MN
MN Appraiser

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!

Nov 22, 2011 04:21 AM #17
Justin Dibbs
Pearson Smith Realty - Ashburn, VA
REALTOR® - Ashburn Virginia Homes for Sale

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.

Nov 22, 2011 05:18 AM #18
Reba Haas
Team Reba of RE/MAX Metro Eastside - Bellevue, WA
Team Reba, CDPE

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!

Nov 22, 2011 06:21 AM #19
Jon Quist
Tucson's BUYERS ONLY Realtor since 1996

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.

Nov 22, 2011 08:36 AM #20
Shar Sitter
Rooms With Style - Minneapolis, MN
Home Staging and Redesign Minneapolis/ St. Paul, M

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

Nov 22, 2011 10:10 AM #21
Reuben Saltzman
Structure Tech Home Inspections - Minneapolis, MN
Delivering the Unbiased Truth.

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 -

Nov 22, 2011 01:38 PM #22
Reuben Saltzman
Structure Tech Home Inspections - Minneapolis, MN
Delivering the Unbiased Truth.

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.

Nov 22, 2011 01:42 PM #23
Reuben Saltzman
Structure Tech Home Inspections - Minneapolis, MN
Delivering the Unbiased Truth.

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 :)  

Nov 22, 2011 01:46 PM #24
Lyn Sims
RE/MAX Suburban - Schaumburg, IL
Schaumburg IL Area Real Estate

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.

Nov 23, 2011 01:36 AM #25
Reuben Saltzman
Structure Tech Home Inspections - Minneapolis, MN
Delivering the Unbiased Truth.

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.  

Nov 23, 2011 03:37 AM #26
Kimo Jarrett
WikiWiki Realty - Huntington Beach, CA
Pro Lifestyle Solutions

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.

Nov 23, 2011 04:46 AM #27
Travis "the SOLD man" Parker; Associate Broker
Team Linda Simmons, Enterprise, AL 36330 - Enterprise, AL
email: / cell: 334-494-7846

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. 

Nov 23, 2011 05:33 AM #28
Marshall Brown
Mid America Inspection Services, LLC - Fargo, ND

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/

Nov 23, 2011 06:12 AM #29
Jayson Holland - Denver, CO
Jay Holland

Another great post! Love it. Thanks again.

Nov 23, 2011 06:19 AM #30
Jan Green
Value Added Service, 602-620-2699 - Scottsdale, AZ
HomeSmart Elite Group, REALTOR®, EcoBroker, GREEN

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!

Nov 23, 2011 10:55 AM #31
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

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. 

Nov 23, 2011 10:57 AM #32
Bob Miller
Keller Williams Cornerstone Realty - Ocala, FL
The Ocala Dream Team

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

Nov 24, 2011 12:04 PM #33
Chris Smith
Re/Max Chay Realty Inc., Brokerage - New Tecumseth, ON
South Simcoe, Caledon, King, Orangeville Real Esta

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

Nov 29, 2011 04:53 AM #34
Sylvie Stuart
Realty One Group Mountain Desert 928-600-2765 - Flagstaff, AZ
Home Buying, Home Selling and Investment - Flagsta

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

Dec 19, 2011 12:27 AM #35
Wayne B. Pruner
Oregon First - Tigard, OR
Tigard Oregon Homes for Sale, Realtor, GRI

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

Jun 19, 2012 03:08 AM #36
Post a Comment
Spam prevention
Show All Comments

What's the reason you're reporting this blog entry?

Are you sure you want to report this blog entry as spam?


Reuben Saltzman

Delivering the Unbiased Truth.
Ask me a question
Spam prevention

Additional Information