Bathroom Mold Remediation

A 1950s bathroom with no exhaust fan, where growth had worked its way behind the tile board and into the wall cavity.

About the project

A 1950s Manitowoc bathroom with original tile board, no exhaust fan, and a window that nobody opens in February. The owners had been cleaning black spots off the grout for years and assumed that was normal.

The challenge

What they were cleaning was the visible edge of something much larger. Behind the tile board, the wall cavity around the tub surround had been damp for long enough that the studs were stained through and the fiberglass insulation had matted and gone black.

Moisture readings on the exterior wall behind the tub were at 31%. The subfloor at the tub apron had begun to delaminate.

The result

The tub surround came out entirely, along with the tile board, insulation and roughly six square feet of subfloor. Two studs were surface-cleaned and treated; none needed replacing structurally.

We rebuilt with cement board, a proper waterproofing membrane behind the new surround, closed-cell insulation in the exterior wall cavity, and — the part that actually solves it — a correctly sized exhaust fan on a humidity sensor, ducted through the roof.

The grout spots have not come back. They were never really a grout problem.

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