Barrier EIFS Around a Bay Window
A 1997 two-story house has barrier EIFS over oriented strand board sheathing. The system has no drainage plane, no weep track at the base, and relies on sealant at window perimeters and at the foundation termination. At a bay window, a 14-inch-wide band of dark biological growth runs below the sill. Sealant at the sill and jambs is cracked and pulled away in several places; no metal head flashing is visible. Moisture readings are 28 to 33 percent in the EIFS substrate about 12 inches below the sill and 15 to 17 percent 6 feet away. The seller's agent asks for a clean pre-listing report and says the EIFS is sealed, so it cannot leak. The buyer is present.
1. Classify this EIFS and explain why the sealant-only defense is unreliable.
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This is a barrier, or face-sealed, EIFS. It has no drainage plane or weep track, so the system depends on the face and sealant joints to keep water out. That is the weakness: sealant is a maintenance item, not a flashing. Once the sealant at the sill and jambs cracks or pulls away, water can enter behind the finish. The absence of a metal head flashing means wall or roof water is not directed to the exterior. The 28 to 33 percent readings below the sill, compared with 15 to 17 percent away from the window, form a plausible wetting pattern. The claim that it is sealed, so it cannot leak ignores both sealant failure and water that enters at other penetrations. OSB is particularly vulnerable to prolonged wetting.
2. What inspection and reporting steps are needed, and how should you handle the request for a clean report?
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I would map the moisture pattern around the bay, probe the finish for soft or delaminated areas, and inspect all window heads, sills, jambs, and the base termination. I would look for missing flashing, reverse laps, sealant adhesion, and any drainage track. I would document the EIFS type and the absence of drainage. Because exploratory openings are needed to see sheathing condition, I would recommend them and state that in the report. I would not issue a clean report; I would write a moisture-intrusion finding with the readings and visible defects, note the limits of the inspection, and recommend evaluation by an EIFS contractor or building scientist. I would also disclose to the buyer, in writing, that the seller's agent requested a favorable report.
3. What repair philosophy is appropriate, and why is recaulking alone not enough?
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The appropriate repair philosophy is to correct the water path, not to recaulk the same failed detail. That may mean removing finish around the bay, installing proper head flashing and sill details, and either restoring drainage or recladding with a drainage EIFS. The sheathing must be exposed and probed; wet OSB cannot be left behind new finish. A sealant-only repair would be a temporary maintenance measure at best, and it would not address water that is already behind the system. The report should give options and consequences, not a single low-cost patch, and should recommend that a qualified contractor design the repair.