Comments on: Does Your Spray Foam Insulation Need a Thermal or Ignition Barrier?

By: David Johnson

David Johnson — Mon, 16 Jun 2014 21:14:05 +0000

Charles spoke of a “huge
Charles spoke of a “huge problem” of convection within cavities not filled with foam. This is a false assertion. The trillions of trapped air cells in foam insulation prevent heat transfer at a rate that would cause those problems. Also the wood framing members are relatively good insulators themselves unless the wood is particularly dense. Convection currents against foam insulation are not the problem he asserts. He also said” the homeowner is literally pissing money away if he pays for this spray foam job – or any job like it – for he will only be gaining a marginal amount of insulation effectiveness.” This is a ludicrous statement. The structure pictured above will have a very effective performance despite his assertions. My only concern is humidity. Closed cell foam does not permit moisture migration and trapped moisture could be a problem, especially if the AC is not running due to moderate to cold temperatures.

By: Sue Cameron

Sue Cameron — Wed, 30 Apr 2014 04:03:42 +0000

Is there a Stayflex thermal
Is there a Stayflex thermal barrier coating we can use on foam board as a thermal coating rather than gypsum board?

By: Debbie

Debbie — Sun, 24 Nov 2013 21:19:07 +0000

I'll give my scenerio with a
I'll give my scenerio with a question to Alison at the end. I'd really like your input, as home owners here get all kinds of stories from foam reps.

in the south we use open cell foam @ the roofline. to meet code's requirement for cathedralized ceilings (as told by code inspector) for the unvented attic, we put 6-7" of open cell..filling rafter bay & faces of 2x's.not the partially filled install in above article which meet code somewhere?? anywhere??
the ignition barrier is the sheetrock of the ceiling to the livng space below.

so is there a problem as you see it Alison with the install as described?

second part of my comment:
I've had concerns with foam in walls with only 2-3" and the resulting air space & convective currents. spray foam for walls is not one of my recommendations to my clients. instead foam sheathing to exterior of walls caulked,taped & sealed. conventional insulation & air tight drywall approach. a better and affordable wall with no extremely long payback like spray foam in walls.

good posting Alison as always. thanks for providing such a great resource for pros & homeowners.

By: Allison Bailes

Allison Bailes — Thu, 14 Nov 2013 03:00:37 +0000

Gary N.:
Gary N.: Yes, foam is a combustible material. So is wood, and we use a lot of it in houses, some of it in the living space without ignition barriers. I'm not trying to make light of the issue; just saying that foam gets a lot of attention, but fire safety is more than just choosing non-combustible materials.

Martin H.: Thanks. I'll add it to the ones already mentioned in the article.

Jim S.: That depends on where it was installed and whether the foam they used qualifies as meeting the fire resistance tests by itself. If they charged you for a coating, the foam probably didn't qualify by itself.

By: Jim Smith

Jim Smith — Wed, 13 Nov 2013 23:17:19 +0000

So the soy-based foam we had
So the soy-based foam we had installed in 2012 did or did not need an ignition barrier ? The installer charged us an extra couple of hundred dollars for a sprayon coating for the foam that supposedly acts as an ignition barrier.

By: Martin Holladay

Martin Holladay — Tue, 12 Nov 2013 18:42:05 +0000

Staycell One Step 255
Staycell One Step 255 manuactured by Preferred Solutions is a spray foam that has passed fire safety tests demonstrating that the foam resists ignition even when it isn’t covered by an ignition barrier or a thermal barrier.

More information here: http://www.greenbuildingadvisor.com/blogs/dept/musings/new-green-building-products-june-2013

By: Gary Nash

Gary Nash — Tue, 12 Nov 2013 02:38:28 +0000

I just skimmed the "
I just skimmed the "Thermal & Ignition Barriers..." from the link above. Looks like this means that a roof assembly insulated with spray foam in an attic will also have to be enclosed with one of these barriers. So now you have the cost of the insulation + the cost of the barrier to sell the Owner on.

Sprayed cellulose is listed as an alternative ignition barrier. Interesting.

Is this going to throw the foam guys for a loop? Walls are enclosed anyway, but roof assemblies are not. Makes cellulose or SIPS panels look like the better alternative.

Anybody else concerned about all of the flammable foam filling a structure? - whether it is enclosed or not.

By: Allison Bailes

Allison Bailes — Mon, 11 Nov 2013 19:51:19 +0000

Armando:
Armando: Thanks! I've updated the article.

Chris M.: Yes, I meant to mention in the article that this applies to both open cell (a.k.a. low density or 1/2 pound SPF) and closed cell (a.k.a. medium density or 2 pound SPF). Foam board insulation also needs to meet the requirements for thermal and ignition barriers, and some products, like Dow Thermax, have gotten approval to be left exposed.

John N.: Thanks for the clarification.

Charles: That photo is closed-cell SPF, and it's not sprayed perfectly uniformly. As long as it has the minimum thickness required (3" on a ceiling here in the Atlanta area), it should be fine. I've discussed some problems with SPF installations in the articles listed in the Related Articles section above. This photo is from about 10 years ago, though, and has no ignition barrier.

By: John Nicholas

John Nicholas — Mon, 11 Nov 2013 18:28:47 +0000

I would point out the
I would point out the limitation of access to and communicating to other spaces has one exception.

If there are ducts or control wires in the space, it needs the ignition barrier.

By: Chris Maher

Chris Maher — Mon, 11 Nov 2013 18:24:35 +0000

Great post. Do the ignition
Great post. Do the ignition and thermal barrier requirements apply equally to .5 lb density spray foam, as well as 2.0 lb density spray foam?

What about the high density foam insulation 2" board stock frequently used in crawlspaces attached to basements?