I just took delivery on a custom made front entry door. Part way into the project, I asked if they would be using a metal threshold (I was sort of leaning this way as I thought wood would ultimately be a bad choice for a threshold). The millwork shop insisted on using the same species as the door (African Mahogany) and insisted that, if properly treated prior to installation and maintained, the wood would last. I conceded (grudgingly). So, the door is here and I am preparing to finish it (threshold and all) in hopes of installing it as soon as the weather improves.
Last summer, I had the brick surround at the front door completely re-pointed and had the masons install a limestone sill for the door (the concrete one was toast). The threshold on the new door will sit on top of the limestone and the block is deep enough that the front edge of the threshold will be set back approximately 2-3 inches from the stone face. My biggest concern is rotting of the threshold and although some may say that it is inevitable, I want to take all precautions to prolong its life.
This being said, I'm thinking that there are two things that need to be considered:
1. The wood threshold needs to be sealed as well as possible to block the penetration of moisture. The millwork shop strongly recommends at least 3 complete applications of a marine varnish to all surfaces. Would this suffice for the threshold as well or should I do a few additional coats? I'm very happy with the way this product will look on the door but perhaps there would be a better product to apply to the bottom of the threshold. Any ideas or advice would be greatly welcome!
2. Obviously, the limestone is quite pourous. In general, I am concerned about moisture wicking into the stone and condensing on the underside of the threshold. Would it be wise to install some sort of moisture proof material at the threshold/sill interface similar to what is used for window flashing? Again, any thoughts!
I can snap and attach some pictures if anyone thinks that they'd be helpful.
Thanks a bundle in advance!
Well, now, there's what's right and what's right and never the twain shall meet.