Document what you're observing
Record the location, onset, any relationship to weather, how conditions have changed, and prior remediation attempts. Photos and basic measurements sharpen the first conversation.
Read the local context
The construction eras here hide moisture in different places, so establishing which one applies shapes where an assessment should start. The frame houses of the older core use plaster, board sheathing and open framing cavities that let air and moisture travel between floors, which means a problem showing on one level frequently began on another. The postwar subdivisions are tighter and more predictable, concentrating trouble in the basement below and the attic above. Across both, a long Michigan heating season drives indoor moisture into cold attic space, where a fan ducted short of the roof stains sheathing every winter.
Consider what disappears from view
Visible growth is only part of the picture -- a thorough plan also addresses water entry, humidity, material condition, containment, and post-work verification. The written scope should explain what preparation and verification happens before everything is sealed back up.
Evaluate complete, comparable scopes
Confirm protection measures, access, materials, permits, testing, cleanup, restoration, exclusions, warranties, and change-order terms are addressed.
What official local sources add
Michigan's climate is what actually drives this, and the heating season is the bigger half. Across a long winter, warm moist indoor air reaches cold attic sheathing and condenses there — so a bath fan discharging into the attic rather than through the roof produces staining, then growth, then delaminated sheathing, repeating every year until the duct is corrected. Humid summers reverse the flow onto cool basement surfaces. The flood overlay matters as history: a property inside it warrants checking wall cavities for contamination from earlier events, not only for what is visible now.
Sources were reviewed 2026-07-19. Confirm parcel-specific flood zones, historic-district status, permits, and current requirements with the relevant authority before authorizing work.