dog door two flapSince a dog door cut through your wall is an opening into your house, it should be as weatherproof as you can make it. For this reason, I like the store-bought dog doors that have 2 flaps on them. These have a flap on the interior of the wall and the exterior of the wall.

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Cutting a hole in your wall is a big deal, and so you want to make sure that the outside actually stays outside. I’ve seen people make their own dog doors, and they really look like they are homemade (remember too that this is a potential entrance point for a burglar).

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Store-bought dog doors get assembled in halves. There is a wall kit that you can buy (usually sold as an addition to the dog door) that bridges the gap between the two halves. This kit keeps all of the wall insulation in the wall and makes for a flawless installation. The two halves mate with the wall kit and then you install long screws in each of the corners to hold it all together.

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I would suggest running a bead of caulking on the exterior of the dog door where it meets the wall. For a smooth surface wall, like siding, you can get away with a lesser amount of caulking. For rough surfaces, like stucco, use a thick bead of caulking and then wet your finger and push it into the crevices to fill the gaps.

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