Are nails okay for flooring the attic?

Question

Our attic has foam insulation and is fully encapsulated. As part of this project, we removed all of the old cellulose insulation above the ceiling, so now there's nothing between the attic joists except for the ceiling drywall. We plan to put flooring for storage in the attic over the joists using 3/4" plywood.

Is it OK to use nails to secure the plywood? If not, what are the problems with using nails? Is it OK to use any type of nail or will it only work with certain kinds? I may get the help of a handyman who is quoting the job based on nails instead of screws, so I'm trying to decide how big a deal this is.

Answer 1

I would use screws because they hold the plywood down to the joist much better. Common nails have the tendency to work themselves loose over time as the plywood flexes and temperatures change.

There are types of nails that would be much better than just common nails. One type is a coated nail that can really help as the coating heats up as the nail is installed and tends to "glue" the nail to the wood. Another type is called a ring shank nail that is designed with circular ridges around the business end of the nail which hold it in the joint by binding with the wood grain.

Another consideration to be made is how the nails are installed over how screws are applied. If the nails are installed using a hammer instead of a pneumatic nailer there is the potential for vibration and flex of the ceiling joists as the nails are pounded in. This can result in visible damage to the ceiling drywall around fasteners.

Answer 2

Flooring in an attic that's mostly used for storage needs very little in the way of fasteners. Nails are certainly fine, though they're more likely to squeak and work up over time.

For the few that are needed, and to minimize trauma to the ceiling below, and because I may want to lift the sheets to access wiring later, I'd be using screws. I wouldn't do a full "screwdown", however. A half-dozen per sheet is adequate.