large nails, split when wood dries, or get looser?

[Tyler Keniston]

So this is a pretty elementary question about nailing / spiking. (Although there may be some complex wood science involved)
I ask because I do a lot of rough bog bridging where pre-drilling is of question.

I understand that green wood is less likely to split when nailed because the moisture leaves the grain more compressible.
Now my question is: when the wood shrinks, is it likely to split even if it didn't when initially nailed green? It seems totally possible, yet I have also read of the phenomenon that nails will become looser when the wood dries. This goes against my understanding of shrinkage (being that as the wood shrinks, so too will a hole in it, meaning tighter compression around the nail). Perhaps it has to do with compression set of the initially drivel nail?

So if you were spiking bridging, framing up a shed of green lumber, etc. and the spikes/nails you are using are not splitting the wood, could you assume the wood won't split as it dries, or could the internal stresses present themselves as splits during drying?

Thanks for any input, I know this is basic stuff.
TK

[Kevin Bourque]

I think a lot of it depends on the species of the wood, and also what type of point the nail has. If you use a sharp pointed nail you are pushing the wood fibers to the sides of the nail which creates tension and when you use a blunt point ( like a cut nail )you basically smash the fibers of the wood lessening the tension. Whether or not it changes when the wood dries I can't say.

[Jeff Duncan]

I don't have a good answer for you, but Kevin's response reminded me of shop class many years ago. Our teachers taught us that blunting the ends of nails would keep the wood from splitting. So for certain things we would actually take the time to hammer the points flat before nailing.

Maybe it's worth it for you to do some test pieces nailed both ways? Won't help you in the short run, but in a couple years when the test pieces have had a chance to dry you would have a good idea of which works better.

good luck,
JeffD

[Mark Rakestraw]

Around here hemlock board and batten siding is generally put up wet/green. I did two barns with this siding and the advice I was given worked out well. The process involved ONLY putting fasteners in the middle of the wide "boards" (generally 10-12" widths). The "battens" were then fastened over the cracks between the wider boards using care not to hit the edges of the wider boards beneath. As the boards dry and shrink in width they are free to move under the battens. By contrast using a faster on each side of a wide board would restrict its need to shrink as it dried, opening up an inevitable crack in the center(this could happen right by the fastener or anywhere between the two fasteners). The fastening strategy described above worked for me and seems to make sense. If the board is not under stress from being restrained from shrinkage by the fasteners I would be very surprised to learn a wet board that is nailed without problems would develop a crack at a later time because of some damage caused by the fastener itself. Instead I think you would need to focus on making sure your fastener placement does not restrict shrinkage across the grain.

[scott vroom]

Tyler: "So if you were spiking bridging, framing up a shed of green lumber, etc. and the spikes/nails you are using are not splitting the wood, could you assume the wood won't split as it dries, or could the internal stresses present themselves as splits during drying?"

It depends on the wood species and dimensions, and the size nail. I wouldn't drive a 16D nail to secure the ends of 3/8" thick x 3" widethick battens, but I don't think twice about toe nailing a 2x4 fir stud into a bottom plate using 16D, with little concern about splitting or coming loose.

The bog bridging I've seen is typically 2x dimensional lumber nailed to either logs or 4x lumber. For that job, i'd use 20D HD galv and nail a few inches in from the board ends. I

[Tyler Keniston]

The "battens" were then fastened over the cracks between the wider boards using care not to hit the edges of the wider boards beneath. As the boards dry and shrink in width they are free to move under the battens.

Interesting. How are the battens fastened? Do you mean that they are fastened over the long edge joints of the wide boards or at butting end joints? Where does the fastener go through on those battens?

ty

[Kevin Bourque]

Around here hemlock board and batten siding is generally put up wet/green. I did two barns with this siding and the advice I was given worked out well. The process involved ONLY putting fasteners in the middle of the wide "boards" (generally 10-12" widths). The "battens" were then fastened over the cracks between the wider boards using care not to hit the edges of the wider boards beneath. As the boards dry and shrink in width they are free to move under the battens. By contrast using a faster on each side of a wide board would restrict its need to shrink as it dried, opening up an inevitable crack in the center(this could happen right by the fastener or anywhere between the two fasteners). The fastening strategy described above worked for me and seems to make sense. If the board is not under stress from being restrained from shrinkage by the fasteners I would be very surprised to learn a wet board that is nailed without problems would develop a crack at a later time because of some damage caused by the fastener itself. Instead I think you would need to focus on making sure your fastener placement does not restrict shrinkage across the grain.

I just completely re-did a pole barn that was nailed improperly. They used green ash for the boards and the battens, and they nailed the battens into the boards instead of nailing into the girts.( that's what we call the horizontal framing members) To make matters worse they used the worst /cheapest boards they could find which were full of big knots, wane edges, and other defects.

[Mark Rakestraw]

260664
Interesting. How are the battens fastened? Do you mean that they are fastened over the long edge joints of the wide boards or at butting end joints? Where does the fastener go through on those battens?

ty

The battens are fastened over the long edge joints. They are only 2 or 2 1/2" wide. The fastener is in the middle of that, into the crack between the wider boards beneath. As you can see from the pic I wasn't content with just one fastener in the middle of the wide board. I put two, spaced only an inch or so apart so there isn't enough shrinkage between the fasteners to cause a split. Probably entirely unnecessary, especially since I used screws.