# 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 '15 at 21:11
• I was thinking I would put the nails in at opposing angles \ / Mar 17 '15 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 '15 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 '15 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 '16 at 1:32

## 1 Answer

Expanding to an actual answer.

Typically finish nails are, as indicated by the name, for finishing touches. I.e. trim, face materials, etc. They are not structural, and are often used in conjunction with other stronger methods.

As I understand you question there are a couple of options

1. Counter-sink screws periodically to provide additional structural support. These can be capped with parts of dowels that match the wood type to hide them.
2. Use a strong adhesive, and add finish nails for support until the adhesive dries.
3. Look into a tongue and groove method, combined with adhesive and nails (which can be hidden in the grooves).

The big issue you are having to overcome is gravity (I still haven't found a way to negate its effects!)

• Anti-gravity nails for sure. Mar 18 '15 at 13:39
• @MichaelKaras Lowes AND HD were all out !!! Mar 18 '15 at 15:36