Attic flooring installation and insulation???

Old 03-25-00, 08:06 PM
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I would like to add a floor to my attic for storage purposes. What type of boards should I use, and what type of nails would you recommend.

I wish to add more insulation, as well. Is there such a thing as too much or too tightly packed insulation.

Also, is there a vapor problem with adding an attic floor?
Old 03-25-00, 09:54 PM
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First, the size and type of lumber you use for the flooring will be limited by what you are able to get into the attic. 5/8 or 3/4 plywood would work just fine, but how wide of a piece can you get in (through the access) and how wide can you use once you get it there (limited by the spacing between the struts in your trusses) As far as nailing, I would reccommend that you screw it down, rather than nail it. 1-5/8" or 2" sheetrock screws would work just fine. The vibration and jarring caused by the hammer when nailing might cause problems (like nail pops and split joints) in the sheetrock ceiling below where you are nailing.

How much insulation you can put in your attic will be limited if you lay boards over the top of the ceiling joists. If your joists are 2X4's you are limited to R-13. If they are 2X6, you can go to R-19. Packing the insulation will reduce it's R value. A thought woudl be to sister 2X4's on top of your joists where you want to add the storage to allow you to add more insulation.

One word of caution through all of this though -- don't overload the attic. Take into consideration snow and wind loads that the roof will be subjected to. If you have to meet say a 30 lb. snow load, adding 10 lbs. per square foot in the attic could create real problems for you during the next snowfall!!
Old 03-26-00, 08:25 PM
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My question is: "is this a true attic or access to the space above your ceiling?"

If it is built like a house that I would build, then you would not have any problems with load. You "should" have at least 2x6 ceiling joists. 2x8 or larger would be the berries. I don't believe that I would touch it if it were only 2x4.

Lefty is correct about access and getting the material into the work area. I dealt with this on a house that I used to live in. It was hardly worth the time when I had to rip down the plywood to 16" just to get it through the opening.

I would also screw it down. 5/8" OSB or CD should work out fine. 3/4" may be a bit much, unless you have the 2x8 or 2x10 joists and will carry lots of weight up there.

Do not compress the insulation and it does not need to be kraft faced.

MTAC - Van Buren,MO
Home repair & Construction

"Where the character and work are always upright"

Anything worth cutting down a tree for, is worth doing right.

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