Q: We live in a new Cape with cedar clapboard siding. Water is leaking in through the exterior door on the gable end of our garage. I've replaced the door's bottom gasket, caulked where the door frame meets the siding, tested the seal on the door's glass by squirting it with a hose, and checked to see if the flashing above the door was installed properly. But no matter what I do, a small amount of water still comes in when it rains. Maybe a small overhang would help—can you tell me how to build one?

— David, by e-mail

A: Norm Abram replies: A door on the gable end of any house is susceptible to leakage because the eaves are too high to shelter it. An overhang isn't usually the solution — that's more for sheltering someone fumbling for keys on a rainy day.

Squirting the area with a hose is pointless. I've used that technique to try to find leaks in doors and windows, but no matter how much water I threw at them, I couldn't recreate the problem.

See if you can pinpoint the location of the leak by standing inside the garage the next time it rains. If water is coming in between the threshold and the bottom of the door, maybe the weatherstripping there isn't adjusted right or is damaged. Or maybe the water is flowing through the joint where the threshold meets the doorjamb. Caulk and a storm door will help in those cases.

But if water is entering beneath the threshold or between the door's jamb and framing, caulk and a storm door won't fix the problem. I'd be willing to bet that there's something wrong with the installation — a properly hung exterior door shouldn't leak. Your house would be better off in the long run if you remove the door along with its casing and properly waterproof the opening. You'll need to remove the nails near the ends of the clapboards and from the clapboard directly above the door opening. That way you can slip strips of builder's felt behind them.

Before refitting the door, slip in the felt and flashing for the head casing and bend them up. Then squeeze a thick bead of butyl caulk along the ends of the siding. After the door is put back, trim the felt flush with the head casing, lay a bead of caulk, and bend the flashing down into it. All that's left is to renail the ends of the siding. And that should be the end of the leak.
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