I thought that I should write a section about installing stair balusters. I know of four different methods and I thought this might be helpful for my readers who are in the midst of a stair installation project. I will include a few graphics to illustrate these particular methods.

The first method that I want to illustrate is actually a method that was used a hundred plus years ago. Although it is not really applicable for stair installer is today, it does have some historical interest. Of course, if you are restoring and old stairway in a period home, this method may have some practical implications. I have had a few customers that were installing new balusters on old stair treads. They cut the bottom of the new balusters to fit into the old stair treads. But I am getting ahead of myself.

Stair installers way back when, cut the edge of the treads with a dovetail pattern as you can see in my graphic. The balusters bottoms were cut to slide into their respective tread dovetails. And finally, the tread return was fastened over the end of the tread to complete the balusters installation (see graphic below). Dovetail construction is still used by many cabinetmakers in drawer construction. It is a very old construction method. But it is not very practical in stair construction. And so, other methods are used today.

baluster assembly dovetail

baluster assembly dovetail

The second balusters installation method is probably the most common method and is still prevalent today. A ¾” dowel pin is turned on the bottom of each baluster. A corresponding ¾” hole is drilled into each stair tread (see below). The balusters are then glued and nailed into the dowel hole. Most stair manufacturers continue to make their balusters with ¾” dowel pins. One of the disadvantages of this method, in my opinion, is that the baluster is not drawn tightly to the stair tread. The next two methods are superior, in my opinion, to this method.

baluster assembly dowel pin

Some time back the owner of a stair company in my locality instructed me about the advantage of using dowel screws (also called double threaded screws). In this method pilot holes, are drilled into the bottom of the stair balusters as well as the top of the treads. A dowel screw is then screwed into the pilot hole in the tread. And finally, the baluster is screwed onto the dowel screw protruding from a top of the tread.

Note: This sequence is important so that the dowel screw does not strip out the pilot hole in the softer wood of the balusters. So make sure you insert the dowel screw into the tread first.

This dowel screw method not only saves time for the installer, but significantly draws the baluster to the stair tread. No glue is needed, nor is it necessary to use finish nails. There are drill bit drivers that are available for purchase that will help in driving the dowel screws into the tread. Be aware that you can also buy centering devices for drilling the pilot holes into the balusters bottoms.

baluster fastening dowel screw

baluster fastening dowel screw

baluster_double_screw_2

The final baluster installation method is similar to using dowel screws. A pilot hole is drilled into the bottom of the balusters and the top of the treads. The pilot hole in the tread, however, is larger to accommodate a threaded insert as shown in the image. The threaded insert is screwed into the tread using a screwdriver or a threaded insert bit driver. The machine threads on the bottom of the balusters are then screwed into the threaded insert in the tread. This method, like the ones cited above, is superior to create a snug fit between the balusters in the tread. Neither glue nor finish nails are needed.

baluster_t_nut

threaded-inserts

threaded-driver-bit

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