I have struggled many a time in the past to create equal, code-approved spacing between deck balusters. The method I’ve come to rely on — the slant-rule technique — has taken all the frustration out of the problem.
With one baluster installed at each end of the railing, I start by measuring the distance between their centers. Next, I divide this number by the desired spacing between the centers of the balusters. Around here, the space can be no more than 4 in. With 2×2 balusters, I divide the railing length by 5-1/2 in. That’s because 5-1/2 in. centers on 2×2 balusters results in a 4-in. space between them.
Let’s say, for example, the length is 158-3/8 in. I divide it by 5-1/2, which equals about 28-3/4. I round up to the next highest whole number: 29. Now I multiply 5-1/2 by 29, which equals 159-1/2. At one end of the deck, I drive a nail into the center of the first baluster. At the other end of the deck, I place my framing square with the long blade parallel to the rim joist and the short blade aligned with center of the last baluster. With my tape hooked to the nail, I find the point on the short blade of the square where 159-1/2 in. falls.
The tape is now at a slight angle to the rim joist, and I can measure off 5-1/2 in. increments with my framing square and mark them on the rim joist to locate the center of each baluster (see drawing). By the way, it helps if you have a calculator that has an add-on function to speed the layout sequence.
Once I began using this method, I was surprised by how fast and effortless it is. With a little ingenuity, I think this technique could be applied to a staircase as well.
Mike Hoffman, Portland, OR