Basement Mold Remediation

A finished basement on the city's north side where a slow foundation seep had fed growth behind the drywall for two winters.

About the project

The homeowners had finished this basement themselves about a decade ago — studs, batt insulation, drywall and carpet directly against a poured foundation wall with no vapor control. It looked fine. It had smelled faintly of damp for two winters, and both of the children had developed a cough that only cleared when the family visited relatives out of state.

Our inspection found nothing visible at all in the finished space. What it did find was drywall reading 24% moisture content along the north wall at the base, against 8% elsewhere in the same room, and a thermal image showing a cold, wet band running the length of that wall.

The challenge

The water was entering through a hairline crack in the foundation about four feet below grade, almost certainly opened by frost movement, and being fed by a downspout that discharged eighteen inches from the wall. It seeped in slowly enough that it never pooled on the floor — it went straight into the bottom plate and wicked up the drywall paper, out of sight, for two full seasons.

Behind the drywall we found heavy growth across roughly forty linear feet of wall cavity, into the insulation and onto the back of the panelling. The carpet pad along that wall was contaminated too.

The result

We contained the basement, ran negative air, and removed drywall to four feet, all affected insulation, the bottom plate section that had begun to rot, and the carpet and pad along the affected run. Framing was HEPA-vacuumed, cleaned and treated, then dried to standard over five days.

The crack was injected and sealed from inside, and the homeowners extended the downspout ten feet with a buried discharge. We rebuilt with mold-resistant drywall on a gap-and-vapor-barrier detail rather than tight to the wall.

Clearance samples came back below the outdoor control. Both children's coughs cleared over the following month.