# How do I calculate the amount of downward force a nail will support?

I have a project in mind that creates a removable panel ceiling, made of wood, in my finished basement. Part of the current design is fastening boards to the 1950's ceiling/floor joists that the ceiling panels will be suspended from. I want to use finish nails installed with a Pneumatic nailer. The wood will be stained a light color.

How do I calculate how much a nail will support? I don't want to use too few nails and have the ceiling fall down, and I don't want to use more than is needed.

Smaller & fewer = more attractive

vs

Bigger and more = stronger.

• I would think the head of the nail would make much more difference than anything. Even a 40d nail that doesn't have a head will allow the board to slip off. Unless you carpet the board with nails, I don't think it will stay permanently. Mar 17, 2015 at 21:11
• I was thinking I would put the nails in at opposing angles \ / Mar 17, 2015 at 21:14
• why not countersink a screw every once and a while and cover with matching dowel. Or, you can use a strong adhesive, at which point the nails are merely for temporary support Mar 17, 2015 at 21:20
• Depending on the weight of the wood, even at angles, the finish nails may straighten/loosen and sag over time. I like @guitarthrower 's suggestion. Mar 17, 2015 at 21:22
• I know this is old but there are some interesting references here. The best way would be to just run some controlled tests with the materials you plan on using, since there are so many variables. One interesting thing I read there was "Scholten found that the highest nail withdrawal resistance values were obtained from sharp tip nails on wood with low density [18]. Wood with high density did not divide after nailing. He proposed common nails for wood with high division resistances." Also, search for pull-out / pull-through strength. Mar 9, 2016 at 1:32