Moved in my newly built Wisconsin house in the first week of November. It's a raised ranch with unfinished full walkout basement. Insulation is fiberglass batting with 4mil poly over external wood walls, and fiberglass, no poly over foundation walls. 2X6 studs.

Decided to pull fiberglass out of one stud cavity cuz poly was cut for furnace wires and wanted to see what's what. They hadn't caulked the hole in sheathing and green spots, which appear to be mold, filled the cavity. So, just on a hunch decided to pull others around basement. Stud cavities were damp, fiberglass backs damp, and sill boxes damp with either mildew or light mold in the boxes. Pretty sure the little hole isn't to blame for the others being damp, etc.

Builder says this is natural. "Had wet fall, building is wet work, etc." Said not to worry about it and just run dehumidifier for year or two straight and all will normalize. So got two going now.

Thinking of closed cell spray foam as one mitigating tool.


  • Sure sounds like the external foundation walls should've had a water barrier installed - especially for a walk-in basement. – Ramrod Dec 23 '16 at 18:58
  • If you add water barriers, make sure that the existing moisture has somewhere to go. – Daniel Griscom Dec 23 '16 at 19:14
  • "not to worry about it" -- there are different types of mold but to my knowledge any is cause for concern and unhealthy to breath. – Tyson Dec 23 '16 at 19:32
  • I would have fans blowing on the wet wood to speed drying and keep track of how much water the dehumidifiers remove. What is the sheathing material OSB or plywood? – Jim Stewart Dec 24 '16 at 18:14
  • Jim it's OSB, with vinyl siding. – gi4ever Dec 25 '16 at 16:08

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