Cold Air Infiltration Into House Under Subfloor

Over the last couple years, I’ve wondered why our master bedroom was on average about 10°F cooler than the rest of the house during the winter. At first, I thought it had to do with poor insulation or that the central air registers in that bedroom were not supplying enough warm air from the furnace. Turns out cold air infiltration was the culprit and it was seeping into our bedroom from two locations.

Air infiltration is a bad thing. No matter how much insulation you have, cold air infiltration leaking into the house will cool it down considerably and quickly. In our case, we had cold air infiltration seeping into our master bedroom from two places. The first and most noticeable was through the windows. Melody Homes (now called D.R. Horton) installed the crappiest, lowest grade windows they could get their hands on when they built the house. Embarrassingly, it took me two years to realize that snow pilling up on the inside track on the window probably wasn’t normal. I figured this was probably the first thing that needed to be upgraded, not replaced. I’ve ordered 5 new very expensive windows for the room and they should be installed late February. They are made by Champion and have had very good reviews. I was also very impressed with the demonstration.

The second place the air was seeping in was less obvious. It was actually coming in from behind the baseboards located on the exterior walls (we had two of them). When I removed the baseboards, I could feel a rush of cold air whenever the wind blew. There was about a 1/2 inch space between the bottom of the wall and the sub-floor. My solution was to use the air-tight expanding foam for window and door seals and spray it in the empty space. Careful, that expanding foam is very messy and you don’t need a whole lot. It expands … a lot.

UPDATE: The windows have been installed and there is an improvement. The room is about 4 degrees warmer than it was before. I still think there is an insulation problem and I’m going to have a home energy audit performed this spring. They cost about $400 but hopefully it will help us find ways of improving our home’s efficiency.

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