AskCodeMan

What is the minimum material for an attic hatch in residential? Seems like it should be equivalent to the ceiling rating. I see everything from 1/2 drywall to plywood to drywall and plywood with sheet metal on the living space side. Also if you could include the appropriate code reference I would appreciate it.

David

Living space or garage attic access?

The living space attic access would need to be of a material which meets the energy code - there is no fire rating to ceilings in one- & two-family dwellings and townhouses.

The garage ceiling in the same structures do not have a fire rating either ... however ... the garage is required to be separated from the living space and its attic.

The garage can be separated from the living space and its attic in two basic ways:
- extend the garage/living space wall all the way to the underside of the roof decking to separate the living space attic from the garage, the garage does not require a ceiling in this case
- install a ceiling in the garage which separates the garage from its attic, the garage attic and the living space attic does not require separation in this case
- the separation is required to be 1/2 inch gypsum board minimum (or equivalent) for the above separation ... plywood, metal, etc is not an equivalent
- any opening in the drywall needs to maintain the same level of separation as the minimum 1/2 inch gypsum board provides

So to be clear you are saying that in a bedroom closet the attic hatch could be 1/4" plywood as long as its insulated to code above and has weatherstripping to seal the opening?

Is there a table in the code to determine fire rating "equivalency" in materials?

David

bigdog wrote:So to be clear you are saying that in a bedroom closet the attic hatch could be 1/4" plywood as long as its insulated to code above and has weatherstripping to seal the opening?

In a bedroom of a one- or two-family dwelling or a townhouse, there are no fire-resistance requirement for the ceiling, I am not aware of a building code section which would prohibit the ceiling from being be paper (provided all the structural aspects were taken care of and the ceiling was not part of a diaphragm ... except that paper would likely not meet the energy code for air and vapor transmission, infiltration and exfiltration for the thermal envelope - plywood? I'm not sure that would meet the energy code requirements either.

If I found that in a new construction house I would want to see what was on the approved construction documents and, if those documents showed 'plywood', then I would inquire with the building official if that was acceptable - if the building official says 'yes, it is acceptable' then there is not much which can be don other than doing some research to see if plywood meets the energy code.

If I found it in an older home, I would state that the attic access hatch should be the same as the ceiling, or someone needs to provide documentation showing that the plywood meets all of the code requirements.

If in apartments or condos, yes, the ceiling is likely fire-resistance rated and then they would need to document that it met the rating of the ceiling (which would likely be 1 hour fire-resistance rated).

Is there a table in the code to determine fire rating "equivalency" in materials?

Not really, that lets architects, engineers, and building officials design and approve alternate methods and materials based on testing or published data. And if the building official is not satisfied with the documents (or lack thereof) presented to him/her, the code allows the building official to require testing to prove it will work ... all at no expense to the AHJ - smart building officials like to see signed and sealed engineering proving alternate methods and materials work as that covers them and their decisions ... albeit some building officials will accept any signed and sealed document, regardless how 'wrong it looks' without requesting additional information - and that can come back to bite them for stepping outside their authority.