Step 4 – Drilling Holes
Some installs will have holes leftover from the old wooden balusters and some installs will be left with a flat surface.
Make sure the top holes in the bottom of the handrail are large enough for the baluster to fit. Make sure you drill at least 1 to 1.5 inch in the handrail.
For the bottom holes on the tread, it is best that these are only 1/4 to 1/2 inch deep.
If you are not using shoes, make sure your holes are drilled as tight as you can for round balusters. Using square balusters, punch out a square hole for best results.
The goal is to have enough room up top to slide the baluster in, and then drop it down into the bottom hole.