Attic floor vs 2nd floor subfloor material

Old 05-29-04, 12:48 PM
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Attic floor vs 2nd floor subfloor material

Hi all:

I am about to put down an attic floor and was thinking of using cut sheets of 3/4" plywood... but also have dreams of adding a second floor one day.

Can anyone advise how to satisfy both requirements?
Are there any substantial differences between material and method used for these (attic floor vs 2nd story subfloor)?

Thanks in advance for any replies,


Last edited by mikeglan; 05-29-04 at 02:50 PM.
Old 06-04-04, 12:23 PM
Ed Imeduc's Avatar
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Take and use 3/4 T/G plywood. it will work just fine for a floor when you build on up there

Old 06-09-04, 06:07 PM
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Thanks Ed!!!

...and didn't I see something in the Forum about using nails vs screws and gluing in either case?

Thanks again,

Old 06-12-04, 08:56 PM
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Just to followup with what Ed said, I would suggest you think about what you are doing if you desire a 2nd story at a later date. Not knowing what you have for room now up there, ceiling height, end goal for the 2nd story i.e. bedroom, bathroom, etc, makes it hard to suggest much at this point other than to direct attention to the proposed floor system.

Issues of concern that I have with your idea is this,

1. Attic storage is rated at 20 lbs per sqft.
2. Habaitable spaces are to be rated 40 lbs per sqft.
3. Intentions of builing on top of the new 3/4 T & G plywood will not suffice if we are talking inadequate existing ceiling joists to accommodate the new load requirement at 40 lbs.
4. I would suggest that you either hold off on adding 3/4 plywood and go with less expensive lumber for "temporary storage" purposes. Options may be 1x stock, screwed for easy removal - no adhesive, easier to manuever in tight spaces.
5. Determining the new load requirement and matching this with proper sized floor joists (or sistering up to strengthen existing ceiling joists) is crucial to avoid flexing of the new floor based on span requirements.

Again, spending money now just to have to remove it to meet code is not a wise idea.

Just some thoughts, hope this helps!

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