Look past the surface stains
A patch of discoloration on the roof deck rarely tells the whole story. In Durham's hot, humid summers, sealing off ventilation gaps, checking for roof or flashing leaks, assessing the wood and insulation underneath, containing dust during removal, and confirming conditions afterward all matter as much as the visible spots.
Build a complete scope
- The source of the moisture, established before cleaning is priced
- Whether the crawl space, the attic, or both are actually involved
- Containment in older open framing, where air moves between floors
- The removal-versus-clean line and how it was decided
- Verification, and the ventilation or drainage fix that prevents a repeat
Durham context
Durham's climate supplies the moisture and its housing supplies the cavities. Humid Piedmont summers push warm outdoor air into cool crawl spaces over clay that stays wet for days after rain, and it condenses on framing and insulation through the entire cooling season without a leak anywhere -- which is why so much of this work involves a space nobody has looked at. Dense tree cover slows drying on every shaded elevation and keeps the ground beside a foundation damp. The heating season reverses the direction, carrying indoor humidity into cold attic space, so a bath fan terminating short of the roof produces staining every winter until the duct is corrected. Older assemblies in the nineteenth-century districts and streetcar neighborhoods complicate the work, because plaster, board sheathing and balloon framing move air and water between floors in ways modern construction does not.