I have a room that I want to both install 5/8" bamboo flooring and a new exterior french door. The wall has to be opened up and re-framed for the door. The base floor is 1 1/2" T&G pine. My question is: should I first re-frame the wall, then install the flooring to the outside (exterior) edge where the new door will go (under the threshold) or install the door first and floor up to the threshold? My inclination would be to run the threshold over the finished floor, but I’m a bit worried that weather will do a number on the exposed flooring under the threshold.
Thanks!
Under all normal circumstances you would install the door first (all exterior doors that I am familiar with come with their own threshold) and then butt up the flooring to it. You would then install a quarter round or shoe molding to cover the joint. Before you install the door, you should first install an adhesive membrane under the threshold to prevent any potential moisture from damaging the subfloor underneath. If your french door did not come with a threshold you can pick one up at Home Depot or Lowe’s, but it also probably means that it is not an exterior grade door and thus not suitable for that type of application.
Do not run your flooring to the exterior, because it will be ruined by the elements. Re-frame the wall first. In the door opening put in a green treated piece of material (I would recommend plywood) that is about an inch narrower than your wall and thick enough that it will flush up with the hight of your new floor. Then install the flooring so it will just be under the threshold around a half inch or so, making sure to leave room for expansion between your flooring and the treated material. Then install the door using generous amounts of silicone under the treshold.