Cutting down on air infiltration in old houses without changing their character can be a challenge. For example, an aluminum threshold with a vinyl seal would certainly cut down on the air leaking under a front door. And it would be just as certain to look out of place.
The drawing shows a technique that we use to keep the wood thresholds in old houses while still cutting down on air leaks. First, we trim the bottom of the door to leave a 3/8-in. gap between the door and the threshold. Next, we cut a 1/2-in. by 1/2-in. groove in the bottom of the door. Then we secure a strip of EPDM rubber roof membrane in the groove. The strip is held in place by 2-in. screws run through a length of 12-ga. Romex wire. With screws about 4 in. apart, the Romex acts as a clamp, spreading out the holding power of the screws.
We trim the two protruding rubber strips so that they are each 1/2 in. long. They make an effective, inconspicuous (and easily replaceable) seal for the door that is also in keeping with the character of the house.
Don Mathis, Macomb, IN
Edited and Illustrated by Charles Miller
From Fine Homebuilding #188
