I found the draft by accident. I was sitting on the floor one cold evening and felt a thin stream of cold air hitting my ankle, coming from a wall outlet. I put my hand over it and sure enough, outside air was seeping right through the socket.

It sounds small, but every outlet on an exterior wall leaks a little, and together they add up to real money on your heating bill.

The five dollar fix

The solution is a foam outlet gasket, a pre cut piece of foam insulation that sits behind the outlet cover. You can buy a bag of them for a few dollars at any hardware store.

1. Turn off the circuit breaker for that room. Never skip this step.
2. Unscrew the outlet cover and set it aside.
3. Peel the backing off the foam gasket and press it over the outlet.
4. Screw the cover back on and trim any foam that peeks out.

It takes about two minutes per outlet. I did every exterior wall outlet in the house in one afternoon and spent under ten dollars total.

Why this works

The gap around an electrical box is one of the most overlooked air leaks in a house, right up there with the gap under an exterior door. Insulation batts often get pushed aside when the outlet box goes in, leaving a cold channel straight from outside to your room.

The gasket does not fix the gap inside the wall, but it seals the face of the outlet, which is where the draft reaches your living space.

My one caution: if the foam does not sit flat because the box is recessed or the cover is warped, the seal will not hold. I had one outlet like that and had to add a little extra foam around the edge to fill the gap.

The rooms feel noticeably less drafty now, and that cold ankle trick does not find anything anymore.