The gap under your door is a straw for your heating bill. A quarter-inch gap on a standard door leaks about as much air as a small open window. I checked mine with a flashlight on a windy day and watched the light flicker from the draft.

You can fix it in five minutes with a door draft stopper, and you have two easy options.

Option one: the adhesive strip

The cleanest fix is a self-adhesive foam or rubber strip that sticks to the bottom of the door. Cut it to length, peel the backing, and press it on. It seals the gap while the door still opens and closes normally. This is the best option for a door you use every day, because it is out of the way and permanent.

• Clean the door bottom with rubbing alcohol first so the adhesive actually holds.
• Cut the strip slightly shorter than the door width so it does not drag on the frame.
• Check that the door still swings freely before you close it fully.

Option two: the fabric tube

The other classic is a fabric draft blocker, a long tube filled with sand or rice that you lay against the bottom of the door. You can buy one for a few dollars or make one from an old towel and some rice. It works great and it is portable, so you can move it between doors as needed.

The downside is that you have to step over it or kick it aside every time you use the door. For a door you rarely open, like a garage entry or a spare room, it is perfect.

Do not forget the door sweep

For exterior doors, a door sweep is the heavier-duty version. It is a metal strip with a rubber or brush bottom that screws onto the door. It lasts for years and seals far better than the adhesive strips. If you have a front door with a big gap, this is worth the extra ten minutes.

Check the weather stripping on the sides too

While you are down there, run your hand along the sides and top of the door. If you feel air coming in, the weather stripping is worn. It pulls off and replaces in minutes, and it seals the whole door, not just the bottom.

I sealed my front door with a sweep and replaced the side stripping on a Saturday morning. The hallway stopped being drafty, and my heating bill dropped enough to notice. Five minutes and a few dollars, and the payback is all winter long.