Start with conditions, not a product
Mold on a crawlspace joist is downstream of the actual issue. Getting ahead of it means finding where water is getting under the house, tracking humidity at grade level, judging how far it's traveled into framing, keeping the crawlspace sealed off from the living space during work, and confirming it afterward.
Build a complete scope
- The moisture source, established before any cleaning is quoted
- Whether uphill groundwater or attic ventilation is driving it
- How the work area is contained, harder in open early-1900s framing
- What is removed versus cleaned, and the basis for that decision
- Verification afterward, plus the drainage or venting fix that prevents a repeat
Asheville context
Homes built into Asheville's hillsides frequently have crawlspaces on a slope rather than a flat pad, with uneven vapor barriers and drainage that was never designed for the volume of water a mountain storm can send downhill in an hour, which is a very different problem than a crawlspace under a level piedmont lot.