Comments on: Beware of Roofers in Homes with Spray Foam Insulation

By: Brandon

Brandon — Mon, 08 Dec 2014 08:50:55 +0000

Also we are in Austin.
Also we are in Austin.

By: John

John — Wed, 03 Sep 2014 04:30:32 +0000

I have 2 gable vents, one at
I have 2 gable vents, one at each end of my roof. I was looking to install soffit vents. Is it possible to have too many soffit vents?
Also, does spray cellulose insulation need a vapor barrier since cellulose is made out of paper?

By: Debbie

Debbie — Fri, 22 Nov 2013 10:50:05 +0000

Having worked in my field for
Having worked in my field for 15 years I've seen a lot of foam installs. Open cell for the most part, but a few metal buildings built for residentail that required closed cell.
(hot humid south)
I have some pictres of excellent open cell foam installs. full rafter depth with no voids or bellys in the foam. fully covered faces of 2x6 rafters.
these companies...and they are far and few between...consistantly do good jobs.
testing the attics for leakage with a blower door, the owners/installers (I should say owners are the installers) do consistant R-25 installs, air tight
at eaves to ambient.
code allows us to drop from R-30 required to R-25 as cathedralized ceiling requirement.
in my years in the energy rating business of inspecting, verifying & testing installs...3 companies consistantly met requirements.
out of the 20+ companies that are
currently in business, have gone out of business etc.

I can't think of any occasion ever that foam was installed on a tile or slate roof. IMO to do so would just be a waste of the homeowner's money.

good job Alison, keep it up!

By: Allison Bailes

Allison Bailes — Thu, 21 Nov 2013 01:32:28 +0000

Jason H.:
Jason H.: Good question. I'm not sure I remember that part of the story clearly, but I think the roofer was there for something, maybe new shingles, and saw that the fan had been removed so they reinstalled it (or put a new one in the old one's place). Also, the spray foam contractor did a poor job, and I think they came out more than once to try to make their work right, so maybe that's how foam ended up on the wire.

By: Jason Hoerter

Jason Hoerter — Thu, 21 Nov 2013 00:47:39 +0000

Allison: Missing from your
Allison: Missing from your article is a clear understanding of why the attic fan was installed. I can assume that the homeowner had their shingles replaced and the roofer insisted there should be ventilation? Also, there's foam on one of the wires, so are you sure the fan wan't there when the foam was installed? Then, who convinced them to remove the fan and now, was anything fixed? I need more background.

Steve: I also watched that movie and it was excellent. A great example of science winning over politics and being true to your self.

By: Allison Bailes

Allison Bailes — Tue, 19 Nov 2013 22:59:41 +0000

Jeff: Now
Jeff: Now you've got me wondering if I've shown any nice foam job photos. I think I have, but I can't quickly think of which articles they're in. I do have some nice foam photos, though, so let me try to rectify that in an upcoming article.

Steve W.: I thought normalization of deviance was just how we all live our lives. ;~)

Gary N.: Don't know if the line is still hot or not, but hey, the wires are safetied off with wire nuts. You're absolutely right, though. That's poor workmanship.

Charles: In a cold climate, open cell spray foam on a roofline definitely needs a vapor retarder. Here in Atlanta, vapor diffusion isn't going to rot the roof unless the humidity in the attic is too high.

By: Allison Bailes

Allison Bailes — Tue, 19 Nov 2013 22:31:12 +0000

Ted:
Ted: Thanks!

Bill S.: Great job! It's too bad that there are so many companies like that out there, but it's nice when you catch something like that and nip it in the bud.

Bill H.: Yep. I wish we could blame it all on them, but that wasn't the case in the home I wrote about here.

Rick W.: Yes, ideally you want all the rafters/top chords covered with foam. Atlanta's not as harsh on that kind of thermal bridging as Cincy, but it's still a problem.

By: Jeff

Jeff — Tue, 19 Nov 2013 20:39:34 +0000

There's only a couple name
There's only a couple name brand foams that have r values as low as 3.6... The most obvious being a Canadian product. Our name brand R is 3.83. Technically, if we are spraying exactly 5" (code allows for a +/- 1/2") we have R-19.15. So, in the world of astrophysics, being off by .85 I'm sure will make a astronomical difference over the course of light years of celestial bodies and beyond. However, we tend to be liberal and on the + side of application thickness so it's quite easy to go over an R-20 ... Not to mention that an additional .22" (R .85) of foam only adds 3 cents material cost and no additional labor costs so we feel clients earned that 3 cents when paying for a good SPF job.

Depending on what climate zone the home is located there must not be a vapor barrier on the open cell foam. In zones 1 and 2 installing a vapor barrier on the bottom side of foam in the roof-line goes against the basic prerequisites of building science, especially in the south zones 1 and 2. BSC has a wonderful picturesque illustration - also supported by FSEC, EEBA and SouthFace - of exactly how the attic, which is now treated as conditioned space (key words, conditioned space), must be arranged/set-up/organized for best installation practices.

General rule of thumb:
North - vapor barrier on inside of conditioned envelope.
South - vapor barrier on outside of conditioned envelop.
These basic A,B,C's of remedial building science hold true regardless of what insulation is applied.

By: Charles

Charles — Tue, 19 Nov 2013 18:44:25 +0000

Open cell spray foams have R
Open cell spray foams have R values of around 3.6 per inch, not 4 as noted in above comment. 5" of open cell is therefore about R18, not R20.

And why would ANYONE install open cell spray foam in a vaulted space without a vapor barrier? There is another name for open celled spray foam - it's called "sponge". It works great as long as there is no moisture (which will significantly decrease R value), but when you vault a space and spray in open cell foam, rising humidity can really soak that foam over time, and holding moisture next to wood is not exactly best practice, especially in southern humid environments. Closed cell with a thermal or ignition barrier would be a much better way to go - either sprayed in or structural insulated panels (sips).

By: Steve Waclo

Steve Waclo — Tue, 19 Nov 2013 01:28:24 +0000

Hello all,

Hello all,

Just watched the BBC movie (recommended) on the Shuttle Challenger disaster and decided to further refresh my memory of the event by reading the Wiki.

While this line from the article may be a bit of a stretch in regard to the situation Allison shared, I believe it does address one of the shortcomings of human reasoning, and worth repeating. I believe Ms. Vaughan (below) was referring to our propensity for saying "...nothing bad has happened yet because of (fill in the blank), so don't be concerned."

The quote:

"This phenomenon was termed "normalization of deviance" by sociologist Diane Vaughan in her book on the Challenger launch decision process.[6]"

Apologies for dredging any bad memories of the Shuttle program...

Best wishes.