Stucco Moisture Testing & Remediation in Minneapolis, MN

Stucco moisture testing and remediation deal with the problem Minnesota has learned about the hard way: water getting behind stucco and staying there. When the City of Woodbury surveyed its stucco homes built from about the late 1980s through 1999, 26% showed visible moisture damage in 1999, and by 2011 the city reported that 451 of 670, about 67%, had failed and been repaired. Many of those repairs involved structural damage and mold, and the city reported many cost $150,000 or more. The damage often stays hidden for years because the stucco itself can look normal.

Who should test

• Buyers of a stucco home built since the late 1980s, before the purchase is final
• Sellers who want to know what a buyer's inspector will find
• Owners planning a recoat, paint job or crack repair on a newer stucco home
• Anyone seeing stains below windows, soft spots, or interior signs like damp drywall or musty smells near exterior walls

How probe testing works

Minnesota inspectors who specialize in stucco use invasive probe testing. Small holes, about 3/16 inch, are drilled through the stucco at the spots most likely to leak, such as below window corners, at roof-to-wall intersections, beside decks and near the bottom of walls. A probe reads the moisture content of the sheathing behind. Dry, firm readings are good; high readings or soft, missing sheathing call for further investigation. The holes are sealed with color-matched caulk and are usually visible only up close. Infrared scans alone are considered inconclusive for stucco, because a cool spot does not prove water has reached the sheathing. Exterior testing cannot be done in rain and is difficult below freezing.

Testing during a home sale

A seller has to agree to holes being drilled in their house, and testing companies usually require the seller to sign a release first. Plan for that in your inspection period. Results show readings at each test point, which helps buyer and seller talk about the repair in concrete terms rather than guesses.

What remediation involves

When readings show wet or damaged sheathing, the affected stucco is removed, typically from whole wall sections so the damage can be traced to its edges. Rotted sheathing and framing are replaced, and any mold on the exposed wood is addressed. The wall is then rebuilt with current details: a water-resistive barrier (Saint Paul, for example, requires two layers of Grade D building paper over wood sheathing), proper flashing at windows, doors and decks, kickout flashing where a roof meets a wall, and a weep screed at the base so water that gets behind the stucco can drain out. New lath and three coats of stucco finish the job.

Permits and inspections

Minnesota requires a building permit for re-siding, and its guidance says rotted sheathing or framing exposed during removal must be replaced, with the city contacted about inspecting those repairs. Minneapolis requires building permits when alterations are made to exterior walls. Remediation usually falls in that category, and inspections of the barrier and flashing happen before the new stucco covers them.