Techniques to Prevent Splitting Wood

Like many folks, I've had problems with wood splitting on me when I drive a nail or screw into it. The basic solution is to go as thin as possible with the fastener, but there are a few other techniques as well.

It pays to understand the reason the wood has split in the first place; namely that the nail is displacing the wood fiber and this acts like a wedge to seperate the wood along the grain.

Next, is the wood old? Most wood hardens after it has has a chance to season.  This is why wood just brought home from the lumber yard is easier to nail into than wood that has been in storage for awhile.  The hard wood is also easier to split than new wood. Greyed and weather beaten wood also has a greater tendency to split when nailed or screwed into.

First, try using a box nail or a brad.  The thinner nail displaces less of the wood mass which is the source of the split.

Second, if the nail must be a normal sized one for strength, then the thickness of the wood may be too thin for the needed strength.

Third, drive the nail in farther away from the edge of the wood.  I go with at least 3/4 of an inch from the end grain edge and an inch or more from the side grain edge. Driving the nail or screw at a gentle angle allows for nailing at a greater distance form the end grain edge as well.

Fourth, blunt the nail point.  The blunted point forces some of the fibers of the wood down into the wood along with the nail instead of pushing them aside.  This takes a stronger blow or larger hammer to do the job, so be prepared for the extra resistance.

Fifth, drill a pilot hole.  I usually select a bit that is no more than 3/4ths of the size of the nail shank so the nail will still grip the wood.  For screws, the bit I choose will be slightly smaller than the shank core of the screw. This is the portion of the screw from the area of the threads that doesn't include the threads. It is unnecessary to use a bit that will penetrate as far as the fastener unless the sizes are becoming quite large compared to the thickness of the wood. For common 2 by lumber I would always drill a pilot hole for anything 1/4 inch or more, and use a bit that penetrates as far as the fastener when the shank is 3/8ths or more.