Unvented Crawl Space

[jar546]

There are some rigid foam boards that are approved for use inside crawlspaces but not basement walls. There are some rigid foam boards that are allowed in both and some that are not allowed in either. You have to check each specific brand and type to see.

 

[Rider Rick]

There are some rigid foam boards that are approved for use inside crawlspaces but not basement walls. There are some rigid foam boards that are allowed in both and some that are not allowed in either. You have to check each specific brand and type to see.

As long as the rigid form boards on the inside of the basement wall are covered with Sheetrock that should meet code.

 

[tmurray]

Is it a 2lb or 1/2 lb product? Is the floor of the crawl space concrete or dirt? If concrete was 6mil poly installed?

 

[Francis Vineyard]

Would be best to speak with the person that wrote the ESR.Contacted Icynene for clarification and waiting for a reply.

Francis

Is an ignition barrier; prescriptive or approved coating required with Icynene LD-C-50 in accordance with Section 4.4.2.3 in unvented crawl space per Section 4.4.2?

Mr. Vineyard,

In response to your voicemail please see the attached ESR 1826. Section 4.4.2.3 allows for the use of this foam in an unvented crawlspace provided the conditions in 4.4.2 are followed and the thickness of the foam noted in 4.4.2.3 is not exceeded without the need for a prescriptive ignition barrier or coating material.

Please do not hesitate to contact me should you require any additional assistance or clarification.

Best Regards

Paul W

Building Science Technologist, ICYNENE

 

[Bama dav]

Francis,again I agree but 4.4.2 # 6 requires foundation vents per 408.1. So move on to enclosed crawlspace 408.3( I think) requires a air pathway to the common area that ESR 1826 #3 doesn't allow. The gentleman I spoke with at ICC said there was a problem with this conflict and he said it was on next month agenda to try and resolve.

 

[Bama dav]

Sorry ESR 1826 4.4.2 #3 doesn't allow it.

 

[Francis Vineyard]

The way I see it the conditioned crawl communicates with the interior and has been interpreted to allow an ignition barrier instead of thermal; R408.3 Unvented Crawl Space

Similarly a allowed in cases with up to 2 inches of styrofoam; (rigid board insulation) the ESR under specific approval permits this product up to 3½ in thickness without an ignition barrier in unvented crawl spaces.

Francis

 

[Francis Vineyard]

Let me know what I'm missing.

The ESR is written much like the IRC; general statements that are most restrictive followed by exceptions.

Section 4.3.2 the alternative coating can be applied if the thickness on walls does not exceed 6 inches in accordance with IRC specific approval; ESR section 6.3: NFPA 286.

Section 4.4.2 requires a prescriptive ignition barrier if the air circulates to other parts of the building, but in accordance with section 5.3 of this ESR and the ICC interpretation does not require a thermal barrier for unvented crawl spaces.

Section 4.4.2.3 does not require the alternative coating or prescriptive ignition barrier if the thickness does not exceed 3½ inches.

Francis

 

[Sifu]

What I found is this;

The code allows an unvented crawlspace when it circulates air to the common area.

The code allows foam insulation when installed in accordance with the mfr specs.

MOST Mfr specs (and tests performed) did not anticipate the "circultated air with the common space" requirement.

Intumescent coatings provide an equivalent ignition or thermal barrier depending on the product.

MOST Intumescent coatings are irrelevent because they don't over-rule the stipulated conditions in the ES reports.

This is a problem that must be worked out between the industry and the code making body, not field inspectors.

I have found a lot of conflicts within the ES reports, a lot of circular references. I am leaving it up to the industry and/or the code to work it out. If we spend too much time doing their job they won't be forced to rectify the problems they have created, either by their actions or in-actions. I figure if I can keep on turning down these things they can't seem to make clear, they will figure out a way to make them clear.

 

[jar546]

As long as the rigid form boards on the inside of the basement wall are covered with Sheetrock that should meet code.

But,......not all foam is required to be.

 

[Rider Rick]

But,......not all foam is required to be.

That's good then.

 

[peach]

build it like a mini-basement and you should be good.