Residential Building - Below-the-slab area classification

[nhee2]

Is there a standard which provides guidance for where/when/if areas below a building slab in a residential building should be classified? NEC 511- 516 aren't applicable and I did not see anything in the list of references in NEC 500. I'm not as familiar with IBC/building codes and am not sure if any guidance is provided there.

I'm also not sure it needs to be considered - just chasing a question asked by a colleague.

Thanks

 

[don_resqcapt19]

Why would there be a classified area below a residential building?

 

[petersonra]

In general, I believe anything underground is unclassified.

keep in mind that area classification is about flammable gas, vapor, dust, or fibers.

this implies quite strongly that there is an open space for such things to be in. if that space is filled with dirt...

 

[nhee2]

Why would there be a classified area below a residential building?

I'm not sure there is - the concern was migration for surrounding earth into the subslab area. I thought i remember hearing about similar concerns in CA area, but don't know if it is a real concern or if there are any building codes which discuss it.

Quite likely that there is not a reason to classify.

 

[rbalex]

There is no general requirement to classify underground locations although Article 514 effectively treats locations below classified locations as if they were Division 1. See Section 514.8.

Some local Jurisdictions may classify the underground. For example, the LA basin treats some below-grade locations around oil and gas recovery sites as classified; however, the usual fix is to install vapor-proof membranes over those locations

 

[nhee2]

There is no general requirement to classify underground locations although Article 514 effectively treats locations below classified locations as if they were Division 1. See Section 514.8.

Some local Jurisdictions may classify the underground. For example, the LA basin treats some below-grade locations around oil and gas recovery sites as classified; however, the usual fix is to install vapor-proof membranes over those locations

thanks.

This area is not below other classified areas. I need to understand why they suspect / think there is methane migration or a need for classification. (It's not in the LA basin). I thought i remembered reading about classifying basements/below grade areas beneath residential - but i am thinking that may have been related to methane detection systems in those areas, not area classification.

 

[rbalex]

thanks.

This area is not below other classified areas. I need to understand why they suspect / think there is methane migration or a need for classification. (It's not in the LA basin). I thought i remembered reading about classifying basements/below grade areas beneath residential - but i am thinking that may have been related to methane detection systems in those areas, not area classification.

That's certainly a possibility. Various local jurisdictions often have their thoughts. I think the LA basin requirements were overkill. I reviewed the original design plans and specs and couldn’t find any reasonable justification or qualifications by the person that developed them. This is not to say they weren't qualified, I just couldn't determine it.