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Securing attic flooring

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  • Securing attic flooring

    I am putting down some plywood boards in the attic to facilitate storage. Would a pneumatic finish nailer do the job or is that too light duty? Are screws a better option?

    I've been trying to justify buying the PC combo kit for a while for other jobs and thought this might be the push I need.

  • #2
    I wouldn't use finish nails. The primary purpose of the flooring is to keep you from stepping through the ceiling of the floor below. The primary purpose of the fasterners is to hold the boards down. Finish nails, because they have no functional head, don't do that well. If you want to nail, use full head framing nails. However, I just did this job and I used screws (sheetrock screws) because I may want to lift the plywood someday (add more insulation; service an electrical box) and pulling the nails is hard.

    Remember that it is critical that the edges of the sheets that are parallel to the joists have to lie on a joist; you don't want any such joints hanging in space between joists. This is easy if your joists are on 16-inch spacing, since three joist bays exactly equals the width of a 4x8 sheet of plywood. In my case, we couldn't get 4x8 sheets up to the attic, so we cut them to 2x4 sheets and it worked out quite well. Use 3/4 ply at a minimum, and eat your Wheaties the morning before you hump all that ply up to the attic.


    • #3
      Yes, I'll have to cut them into 2x4' sections too. How did you manage the edges that way? Share a beam with half for one sheet of ply and half for the other?


      • #4
        Exactly right. The screws for the end that rests on half a joist have to be canted a bit, and remember, you can't start a screw quite as close to the edge of ply and you can with a board of solid wood. However, you'll also run a course of screws into the interior two joists, and these will insure that the small sheet can't shift off the "lip" of the border joist.

        The hard part is, as I said, humping the ply up (in my case) two flights of stairs. What I did was to use a two-wheel hand truck, with 4 small sheets per load, pulled backwards up the stairs. Keep your back straight and do what amounts to shallow deep knee bends for each step. By the time you're through your thighs will be aching, but that's better than throwing your back out.

        The only other pointer I can add (based on experience) is to take some time making sure the first course of small ply sheets (the one closest to the end wall) is square to the joists. Each successive course will key off the one before it, and if the first course is cocked, but the time you get 3 or 4 courses down, the sheets won't fit too well.


        • #5
          If you run into a floor joist that is running off true, you can sister some sleepers along its length to screw the plywood to. If you see too much tear out when you screw the flooring down just add some 2X scraps to the side that you need them on.