Moldy barn tack room
I need help trying to remedy a mold issue. The cement floor poured in the barn has no vapor barrier or insulation under it which was not a problem until we built a 9’x10′ tack room in one corner (to store saddles, etc) and installed an electric baseboard heater. We also installed tile on top of the cement floor.
I have found some mold growth in the sheetrock on one wall and the room smells musty/moldy. I have wiped all the walls and will remove & replace the moldy section of sheetrock, but am trying to figure out how to prevent future problems.
Most of the moisture (I think) is from condensation on the cold floor in the heated space. I’m not sure if moisture is wicking up through the slab and through the tile floor.
We are in MN and have very cold winters and very humid summers. The door swings inward and does not have a lot of clearance but I think I could fit a layer of that thin fan-fold rigid insulation (about 1/4″ thick?) and a sheet vinyl flooring on top.
Would that be enough of a insulating barrier to stop the condensation? Would it still get condensation underneath and then seep up into the sheetrock walls? Any other ideas that don’t involve jack-hammering up the floor?
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Replies
Definitely an issue (I threw away a saddle ruined by mold). The primary solution is to install a dehumidifier. With a drain to outside and a humidity meter (so you can frequently check that it's still working). You could air seal better and apply clear epoxy to the floor to reduce dehumidifier run time.
If you installed a glazed tile on the floor, that forms essentially a moisture barrier (to both vapor and liquid water) leaving moisture movement confined to the tile joints (standard sanded latex grout being very permeable while epoxy and polyurethane grouts are highly impermeable).
Part of the problem is simply the gypsum wallboard; the paper is very hard to protect from mold. I always use a paperless gypsum board in high-moisture areas, such as USG Fiberock or any of the fiberglass mesh facing products, such as GP Densglass.
In terms of dehumidifiers: if you keep the tack room pretty cool, you will need a dehumidifier that does not have freeze up at the coils; consider Santa Fe dehumidifiers that work down to 50F. To dehumidify below that, you probably need to look into enthalpic, wheel-based dehumidifiers, such as the ones used in hockey rinks. Take a look at this BuildingGreen Primer that I wrote some time ago: https://www.buildinggreen.com/primer/how-active-dehumidification-works.
Peter