Open the wall on an aging Twin Cities building and some rotted sheathing is the rule, not the exception. The question is never really whether you’ll find it — it’s whether the contract already set a price for it before the crew is standing at an exposed, rain-threatened wall with the leverage. A contracted rot-repair allowance answers that question in advance: a per-square-foot unit price agreed before work starts, documented with photos, and approved through a defined change-order process.
Why hidden rot is so common here
Why does Twin Cities siding hide so much rot?
Because Minnesota’s signature siding failures were, at bottom, water getting behind the cladding and into the wall. The state’s well-documented stucco and EIFS moisture problems traced largely to window, door, and flashing detailing — water that slipped past the cladding and rotted the sheathing underneath. The same wall-cavity moisture story sits behind swelling LP/hardboard composite siding from the 1985–1995 Inner-Seal era, and behind any building where the flashing was wrong from the start.
You don’t know how much sheathing is gone until the wall is open — which is exactly why the contract has to anticipate it rather than react to it.
The rot-repair allowance
What is a rot-repair allowance and why have one?
A rot-repair allowance is a contracted unit price — for example, a set dollar figure per sheet or per square foot of sheathing — that the contractor charges for repairing rot beyond what’s visible at bid time. Agreeing the rate before the wall is open removes the leverage problem: you’re not negotiating price with the crew standing at an open, rain-exposed wall.
Without an allowance, every rotted panel becomes a separate negotiation mid-project, and the “low bid” that omitted rot repair quietly becomes the most expensive. With one, additional repair is a known rate applied to a measured quantity — predictable, documented, and fair. This is one of the line items a board-ready bid scope should require of every vendor.
What a real change order looks like
What should a change order include?
A legitimate change order documents the condition, the fix, the quantity, the unit price, the total, and the approval. For hidden rot that means dated photos of the open wall, the measured square footage or sheet count, the contracted unit rate applied, the new total, and a signature from whoever holds approval authority — before the repair is buried behind new siding.
| Change order element | Why it matters |
|---|---|
| Photo documentation of the condition | Proves the work was needed; protects both sides |
| Measured quantity (sq ft / sheets) | Ties cost to something verifiable |
| Contracted unit price applied | No mid-project renegotiation |
| Running total against the allowance | Board sees the budget in real time |
| Written approval before burial | No “surprise” invoices at closeout |
Approval authority and thresholds
Who approves change orders, and up to what amount?
Set approval thresholds before the project. A common structure lets the community association manager or project contact approve routine change orders up to a dollar limit, with anything above that going to the board or owner. That keeps the crew moving on small rot finds without waiting for a board vote, while preserving board control over anything that meaningfully moves the budget.
For a self-managed association, designate one person — often the Treasurer or Buildings chair — with a clear limit and a duty to report all change orders at the next meeting. For apartments, the on-site or regional manager works to a capital limit set by ownership. The point is that no one is improvising authority while a wall sits open.
Budgeting for the unknown
How much contingency should the budget hold?
Because rot quantity is unknown until the walls are open, the funding plan should carry a contingency for it — a reserve within the project budget specifically for change orders. The contracted unit price tells you the rate; the contingency covers the quantity you can’t see. Boards that fund this up front avoid going back to owners for more money mid-project.
This matters most where the budget came from a special assessment, since asking owners for a second assessment because the first didn’t anticipate rot is exactly the credibility hit boards fear. A contingency in the range of roughly 10–15% of the project cost is a reasonable starting point for an aging building of unknown condition — adjust it up if the building’s history (failed stucco, old composite, known leaks) suggests heavier damage, and confirm the figure against your contractor’s experience with comparable buildings. Build it into the original ask. The funding mechanics live in paying for siding.
FAQ
Change orders and hidden rot — common questions
Q: How much hidden rot should we expect? There’s no universal number — it depends on the building’s age, the original siding and flashing, and how long water has been getting in. The right posture isn’t to predict the quantity but to lock the unit price in advance, so whatever turns up is priced at a known, fair rate instead of negotiated mid-wall.
Q: Can a contractor inflate rot to pad the bill? That’s exactly what photo documentation and measured quantities prevent. A real change-order process requires dated photos of the open wall and a measured square footage before the contracted unit price is applied — so the board can see what was found and what it cost, not just a lump-sum surprise.
Q: What if the original bid didn’t include a rot allowance? Treat it as a red flag, not a bargain. A quote with no sheathing-repair allowance simply pushes that cost into a mid-project negotiation with no agreed rate — you pay either way, just later and with less leverage. Require an allowance in every bid so the quotes are actually comparable.
Q: Does hidden rot repair affect our warranty or maintenance records? Yes — keep the change-order documentation. As-built notes on rot repair and re-flashing feed the association’s preventive-maintenance plan, which Minnesota law ties to preserving rights under the 10-year statutory construction warranty (Minn. Stat. § 515B.3-107).
Reviewed against public source material from Ben Juncker and Craftsmans Choice, without presenting their contractor credentials as this sites own.
Lock the rot-repair terms before you sign anything.
We’ll help you require a rot-repair allowance, a documented change-order process, and a contingency in the scope — so the most common multifamily budget surprise becomes a managed line item your board can defend.
Statutory citations on this page reflect Minnesota law as of mid-2026 (§ 515B.3-107 was amended that year); confirm the current text before relying on it.