HOw deep can a framing nail head be set?

[Robert Ellenberg]

I know they often are set some when an air gun pressure is too high. I have a design feature where I will have some framing exposed and painted. If the heads can be set slightly and puttied, it will have a nicer appearance than a flush painted nail head. However, theoritically the deeper the head is set, the weaker the lumber member connection. Is there a standard anywhere that gives any specifics on this?

 

[ICE]

I know they often are set some when an air gun pressure is too high. I have a design feature where I will have some framing exposed and painted. If the heads can be set slightly and puttied, it will have a nicer appearance than a flush painted nail head. However, theoritically the deeper the head is set, the weaker the lumber member connection. Is there a standard anywhere that gives any specifics on this?

What is the application? Adjusting a nail gun with pressure regulation is difficult and not consistent. I had guns with a flush nail adjustment feature for siding and trim. Without that feature, the nails would always be countersunk. Going for countersunk shouldn't be too big of a problem. As I recall, 90psi was right for the guns so if you set the flush nail attachment for the depth you want, it might work.

As far as a standard goes, I doubt it. I did have a contractor do his best to convince me that there were accepted trade guidelines for countersunk nails in plywood on a panelized roof system but he couldn't come up with anything other than his story.

I have yet to see putty look better than nail heads but I suppose a meticulous painter could pull it off. I have seen putty being pushed out of the hole due to what I assume is expansion and contraction pushing the nail out.

 

[Mark K]

Depends on what the head is into.

If you are dealing with 1x material probably not more than an 1/8"depression. For 2x orthicker material I would think a 1/4" depression would be fine.

If you are nailing plywood or OSB the rule is that the head not bread the surface ply. This is of special concern when these nails are being used to resist wind and/or seismic loads. In these cases it is a good idea to talk with your structural engineer.

The phenomena that ICE is referring to is wood shrinkage. As the wood dries out and comes into equilibrium with the environment the wood will shrink which can cause nail popouts. This can be true for kiln dried lumber although less likely. In some cases screws may be an option but the design values may not be equivalent to those for nails.

 

[peach]

If it's braced/shear wall or roof sheathing, the nails can't be countersunk (reduces the load carrying properties of the panel); that's not theory - it's fact (and a code issue). For non critical/load bearing members, it comes down to appearance.

 

[TimNY]

AF&PA has a chart showing the reduced strength of plywood when the nails are countersunk. As long as you know what strength you need, you could use that chart to justify compliance of nails countersunk in plywood.

 

[Robert Ellenberg]

Sorry I was not clear. I would never try to set nails in sheathing so I didn't even think that way!

This will be exposed ceiling joists and they will set on a ledger. So the nails I am referring to would be the 3 headed framing nails that must be in the ledger just below each joist and the toe nailed framing nails that will be on each side of the end of the joist where it butts into the band (that the ledger is nailed into).

 

[mark handler]

3 headed framing nails ????

 

[DRP]

Oh no, There goes Tokyo!

three nails, the kind what has heads

Don't forget a tension strap over the top of the CJ's tieing the rafter feet together across the building.

 

[Robert Ellenberg]

16d nails have heads and you must have 3 of them in the ledger at each joist.

The joist and rafter will be one in the same. This is a flat roof so I don't believe there would be any straps.