Ask the Architect

More on nailing walls together


Q. In your last column you referred to walls that weren’t nailed together correctly, but I didn’t understand what was supposed to be done to avoid cracks in the walls. Is there a particular way that it’s done to avoid the problems you described?

A. Many architects’ building plans have adopted the nailing schedule from the building codes that prescribes the size and number of fasteners to be used for each type of connection in the wood framing process. For example, in my last column I wrote about how the wall base plate, a 2x4, was nailed to each of the vertical wall studs with one nail, straight through the bottom of the 2x4 base plate and into the bottom of the wall studs. It would be like jamming the stud down onto a small spike. By doing so, the wall stud has the ability to rotate, like an axle.

Once everything is nailed together to form the wall frame, it seems as sturdy as what would have been the correct way, which is to have at least two nails going into the base of the wall stud, at an angle on one side of the stud, and at least one nail on the opposite side. You don’t want to use more nails, because the wood can split. The difference is that the grain of the wood runs with the length of the wall stud and ends at the top and bottom of the stud.

The grain is like a series of straws bundled together very tightly, and once served as the feeding tubes, or capillaries, for the tree. So nailing parallel, up into those straws, versus nailing across them, at an angle, is much weaker. As the wood continues the drying process over the years, subjected to interior changes in humidity from changes of season, air conditioning, heating, etc., there is internal movement in the wood.

I’ve explained in previous columns that when the market for lumber is really good because construction is booming, not all lumber gets the proper time to dry before shipping or installation. When it’s nailed correctly, you stand a better chance of minimizing the movement of the lumber at the most critical joints. End-grain nailing is a weak connection, and not prescribed in the building codes.

There are many factors that play into the continuous movement of buildings, and from experience, testing, observation and practice, the construction industry has evolved to become very effective at making buildings stronger, safer and more flexible in the face of changing needs. Unfortunately, there are many who never bother to pick up a book or search on their phone for the prescribed way to build. One building department even posts pictures on the wall at its counter of the “violation of the month,” and leaves them up alongside the next and the next. It’s a great way to show the public how not to do things. I hope I nailed it.
