So you have finished installing your floor in multiple rooms and now you are looking at the transition between doorways. Not all doorway passages need or require a trim treatment, but when they do you are looking for a threshold molding. These come in two types: a standard threshold and an overlap threshold.
An attractive shot of a standard threshold in Amber Flat Grain
The standard threshold molding is flat on top and tapers on both sides down to the level of your floor. This is designed to fill the gap between the bottom of your door and the surface of the floor.
Palm Standard Threshold
Other advantages of the threshold are to keep the drafty air from coming in under your door, provide a little debris protection from the other side and if installed with caulking underneath the molding, can provide a bit of flood control, say from a bathroom or kitchen area.
An overlap threshold though sharing a name is really a very different type of molding from the traditional standard threshold molding. This product is designed to butt cleanly to a sliding glass door track that can then also receive a caulking treatment to avoid both moisture and debris from collecting between the aluminum track and the installed flooring.
Overlap Threshold, Amber Edge Grain
The overlap threshold also allows for the concealment of the expansion gap that is required around the perimeter of every room.
This is how it works. The overlap threshold at the square nose end is slightly taller than the flooring itself. It is then cut back on the other side to allow the flooring to slide underneath it with the “overlap” coming over and on top of the flooring.
How is it installed? The overlap threshold nose end is squared off to butt to the aluminum framing of the sliding glass door. The flooring is installed to leave both a space for the overlap threshold to drop into as well as leaving room for the required expansion gap between the flooring and the wall. The overlap then coming up over and on top of the flooring, the gap is concealed and the finish is complete.
Smith & Fong Co. offers both types of thresholds, the standard threshold and the overlap threshold.