Some things are easy to see, and others are difficult especially when we are talking about Cold Air Penetration. Let’s face it, trying to see air penetrate can be problematic. However, sometimes it is fairly easy to see how the air is able to move from point A to point B.
Take a look at today’s photograph. I’ll bet that virtually everyone out there has one of these in their basement. What are you looking at? For starters this picture shows a Plumber’s nightmare where all sorts of crazy things have happened all in a very tiny space. We are not going to examine the quality of the work in this picture, it was chosen to demonstrate something that all of us have in the basement.
This is the bottom drain for the tub/shower in the downstairs bathroom. The bottom of the tub sits on the bathroom floor and protruding out from the tub is its drain with the necessary trap.
In order to make the tub’s drain and trap fit it is necessary to cut a fairly large hole in the floor creating room for the pipes. We are not concerned for the moment with the pipes but rather the hole in the floor.
Remember how we said Cold Air penetrates into the basement and then rises up into the living room? Obviously, the air will need a “Path-Way” to follow. And, that Path will be upward because as the cold air is warmed it becomes less dense and expands in volume. The hole in the floor for the Tub-Drain is one of the largest single holes in your home’s building envelope. It must be closed off!
If you want the air in the basement not entering the house this huge hole must be sealed off.
Suggestion: we suggest that you use a sheet of rigid foam that is cut to fit and then “glued” in place probably with a good grade of caulk. If there are spaces here and there that do not fit tightly those can easily be filled with spray foam and with little effort and not a lot of money this huge hole can be sealed off. Also, should you ever need to get at the pipes again it will be very easy to remove the rigid foam.
Is the tub drain wide open in your basement?