40 min. attic access

[Francis Vineyard]

May be overthinking the details but what do you consider an approved ceiling attic access for side by side attached 2-famiy dwellings having the 5/8ths Type X ceiling with the draftstop separating the attic space?

Thanks for your consideration.

 

[north star]

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Because of the way fire reacts & develops, CORRECT sealing of all penetrations

between the side-by-side family units should be paramount, including the actual

attic access opening [ i.e. - seals around the framed opening when the attic access

is closed ].

Increasing the rating of the attic access area is only one piece of the overall

fire protection picture........Removing sources of oxygen for a fire to propagate

is a primary focus.



= + =

 

[cda]

May be overthinking the details but what do you consider an approved ceiling attic access for side by side attached 2-famiy dwellings having the 5/8ths Type X ceiling with the draftstop separating the attic space?Thanks for your consideration.

Can you give code section for requirement

 

[Francis Vineyard]

Thanks north star, but once again I have trouble clarifying what I meant.

To my knowledge the IRC does not address "openings" where the code allows 5/8ths for the ceiling instead of the separation wall to the underside of the roof deck in accordance with section R302.3 exception 2. 2009 IRC

"Wall assemblies need not extend through attic spaces when the ceiling is protected by not less than 5/8-inch (15.9 mm) Type X gypsum board and an attic draft stop constructed as specified in :Next('./icod_irc_2009_3_par079.htm')'>Section R302.12.1 is provided above and along the wall assembly separating the dwellings. The structural framing supporting the ceiling shall also be protected by not less than 1/2-inch (12.7 mm) gypsum board or equivalent."

Then there's requirement for attic access; R807.1

Since this is not a 1 hr. horizontal assembly but a 5/8ths Type X ceiling (40 min.) what criteria if any do you use approve a horizontal assembly for this membrane opening?

For example a typical attic access has wood trim holding the cover above, do you consider the thickness or type of wood and fasteners for equivalency?

If they were to cover an attic access ladder with 5/8ths what about the hinges and screws attachments?

 

[cda]

If you are talking attic access , not in the garage, is the horizontal rating required???

Section please ;;;;;,,,,,,

 

[mjesse]

May be overthinking the details

That's my vote.

Joe homeowner is just gonna leave the darn thing open after he pulls his Christmas lights down from the attic anyway.

5/8" rock resting on wood casing around the opening is the norm here. They do the same thing inside, but now we have to check weatherstrip and insulation to match the surrounding ceiling per IECC.

$0.02 mj

 

[Francis Vineyard]

That's my vote.Joe homeowner is just gonna leave the darn thing open after he pulls his Christmas lights down from the attic anyway.

5/8" rock resting on wood casing around the opening is the norm here. They do the same thing inside, but now we have to check weatherstrip and insulation to match the surrounding ceiling per IECC.

$0.02 mj

It's a penny for your thoughts but I'll accept the extra sense- Mrs. Malaprop.

 

[cda]

R302.12 Draftstopping. In combustible construction where there is usable space both above and below the concealed space of a floor/ceiling assembly, draftstops shall be installed so that the area of the concealed space does not exceed 1,000 square feet (92.9 m2). Draftstopping shall divide the concealed space into approximately equal areas. Where the assembly is enclosed by a floor membrane above and a ceiling membrane below, draftstopping shall be provided in floor/ceiling assemblies under the following circumstances:

1. Ceiling is suspended under the floor framing.

2. Floor framing is constructed of truss-type open-web or perforated members.

R302.12.1 Materials. Draftstopping materials shall not be less than 1/2-inch (12.7 mm) gypsum board, 3/8-inch (9.5 mm) wood structural panels or other approved materials adequately supported. Draftstopping shall be installed parallel to the floor framing members unless otherwise approved by the building official. The integrity of the draftstops shall be maintained.

 

[cda]

Where the assembly is enclosed by a floor membrane above and a ceiling membrane below, draftstopping shall be provided in floor/ceiling assemblies under the following circumstances:

1. Ceiling is suspended under the floor framing.

2. Floor framing is constructed of truss-type open-web or perforated members.