Q: We have a vacation house in coastal Virginia, overlooking Powell's Bay. The interior trim and floor molding of our exterior mudroom door has sustained rainwater damage. We attempted to correct the issue by painting the interior trim with a shellac-stain inhibitor and by applying silicone around the door caulking against the Dryvit exterior. Not being at the house full time, we did not realize that the interior trim continued to be damaged from frequent driving rains. We recently observed that rain was soaking the bottom wood threshold and pooling in each bottom corner of the door inside the mudroom. What is causing this issue and how can we fix it?

Atlantic, Va.

A: Dryvit is a brand name for a type of exterior cladding known as EIFS — for exterior insulation and finish system. It consists of rigid foam insulation board attached to the wall, topped by a base coat of synthetic stucco reinforced with mesh and a textured finish coat of synthetic stucco. It’s waterproof, highly energy-efficient and relatively inexpensive. What’s not to like?

The concept was used successfully in Europe for about a quarter-century before it became popular in the United States in the 1970s. On commercial buildings, which are often framed in steel, it worked well. But for wood-frame houses, water damage started showing up around windows and doors. When contractors pulled off pieces to investigate, they sometimes discovered even relatively new houses were rotting away under that waterproof skin.

Lawsuits were filed, and building experts tried to figure out the issue. They eventually concluded that trying to protect a wood-frame building by covering the outside with a waterproof barrier isn’t a good idea. If a leak develops — which probably will happen eventually — the outer skin traps the water within the wall, leading to decay and mold. Today, most EIFS systems include a waterproof layer behind the foam insulation, plus gaps, channels or other features that allow any water that gets inside to safely drain away.

The lawsuits from past years scared many insurance companies, so only a few are willing to insure contractors who deal with EIFS. Your problem might be unrelated to the cladding on your house, but mere mention that it’s there could make it harder to hire someone to fix the problem. “A lot of contractors won’t touch anything with EIFS around it,” said Brandon Williams, owner of B.K. Williams Construction, a company in Chesapeake, Va., (757-646-4968; bkwconstruction.com ) that does take on EIFS jobs. The company charges $475 for a whole-house EFIS inspection, plus $50 when the address is 30 miles or farther from its home Zip code, 23320. Your vacation house is a two-hour drive away.

There are numerous possible causes, so an inspection would be the first step. Williams and one of the engineers at Dryvit Systems (800-556-7752; dryvit.com ) looked at the pictures you sent and both homed in on the big gaps visible alongside the door’s exterior trim. “The caulking on the right side of the door has definitely failed,” Williams said. Fixing this could be the solution — or just part of it.

Both experts also noticed that there isn’t much of a step up from the tiled patio outside to the door. Especially given that your house is along the coast, wind could be driving rainwater between the threshold and the door. There could also be a problem with the pan flashing under the threshold, or the patio might slope slightly toward the house.

It’s also possible that water is getting into the wall above the door and then draining inside the framing. The water could be coming from a leak at a window on a higher story, a crack in the stucco, a roof problem or a clogged gutter. The pictures you sent don’t show much beyond the door. Williams suggested looking at the top of the door to see whether there is evidence of moisture. Removing the interior trim alongside the door would also help you assess the extent of the problem.

If you’re lucky and there is no extensive damage within the wall, installing new caulking around the outside door trim might be enough to keep water from getting back in. Caulking around EIFS is different from caulking a house with wood siding, Williams said. The gap has to be a half-inch wide — not thinner — and you need to press backer rod, a ropelike material, into the gap before you fill in the remainder of the gap with 100 percent silicone caulk or urethane caulk. Installed this way, the caulk takes on “an hourglass shape” in cross-section, Williams said, and this allows it to stick to both sides of a gap while stretching in the middle. “It needs to stretch because the EIFS is expanding at a different rate than everything around it” when the temperature rises, Williams said.

Williams could recaulk a doorway on the same day as an inspection. But if parts of the EIFS itself need to be repaired, you are probably looking at a two-day job at the minimum, he said.

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