What actually rotted those walls
Picture a window in one of those failed walls. Rain runs down the cladding, reaches the head of the window, and instead of being lapped out over the surface below, it slips behind. There is no flashing tucked into the barrier to catch it and send it back out. So it travels into the wall cavity, soaks the sheathing, and sits there.
Now picture the same building’s roof, where a gable meets a sidewall. A small piece of metal — kick-out flashing — is supposed to sit at the bottom of that intersection and throw the roof’s runoff away from the wall. On the failed houses, it was routinely missing. Without it, an entire roof’s worth of water funnels into one vertical seam and pours down behind the cladding.
Neither of those is a cladding problem. Both are flashing problems. And both kept doing their damage for years before anyone saw a stain.
The barrier that should have been the backstop
Behind the cladding sits the water-resistive barrier — a continuous layer over the sheathing whose entire job is to shed the water that gets past the surface, because some water always gets past the surface. No exterior is watertight in a wind-driven Minnesota rain. The WRB is the backstop.
Minnesota code says it plainly: cladding gets a continuous water-resistive barrier behind it, at minimum one layer of No. 15 asphalt felt or an approved equivalent. (MN Rule 1309.0703) The word that does the work in that sentence is continuous. A barrier with gaps, punctures, or unsealed laps around openings is not a backstop — it is a funnel. On the stucco failures, the barrier was too often discontinuous exactly where flashing should have tied into it: at the windows.
So you had two things failing in the same place. Flashing that didn’t divert the water, and a barrier that didn’t catch what the flashing missed. Together they turned ordinary rain into ten years of slow rot.
What the crisis wrote into Minnesota’s re-side rules
Minnesota didn’t just absorb the lesson. It codified it. When you re-side an existing building today, kick-out flashing is required where it was so often missing the first time — and so are the inspections that confirm the wall is right before the new cladding hides it. (MN DLI re-siding fact sheet, mnspect handout)
The inspection sequence is the part most owners never see, and it is the whole point. A building department typically wants eyes on the barrier and flashing before the new siding goes on, then any sheathing repair the tear-off uncovered, then the finished cladding, trim, and flashing at the end. The order is deliberate. You cannot inspect what is already covered, and the stucco era proved how much hides under a finished surface.
How to read these lessons into a re-side today
A tear-off is the one moment the wall is open and honest. Treat it that way.
- Reuse nothing on faith. If the existing barrier is torn, brittle, or discontinuous at the windows, it goes. New cladding over an old leak path just buys you a slower version of the same failure.
- Make flashing a line item, not an assumption. Window and door heads, roof-wall intersections, penetrations, and kick-outs — name them. The stucco failures were failures of detail, and details left unstated tend to go undone.
- Plan for the inspection sequence, not around it. A scope that expects the pre-cover barrier-and-flashing check is a scope that intends to do the work in the open.
- Open the wall before you trust the wall. Stains below windows or at roof-wall seams are the late symptom. Moisture probing during an assessment finds it earlier.
The stucco crisis was expensive. The cheapest thing about it is the knowledge it left behind: walls fail at the water details, the damage runs for years out of sight, and the time to get the barrier and flashing right is while the wall is open. A re-side that honors that is a re-side you don’t revisit in nine years.
Minnesota’s WRB and re-siding flashing requirements are current as of 2026; confirm specifics with your local building department before scoping.
Related reading: Failing stucco in Minnesota explained · Do you need a permit to re-side in Minneapolis? · What a real multifamily siding bid must include