Moisture under garage mats

Here's my situation: I have an approximately 400sqft garage that I converted to a gym/workshop. Spray foam insulation on walls and under roof deck (no false ceiling, open to the rafters). It's built on a slope, south wall is about 4 feet below grade, north wall is the garage door that is on grade. I don't have any moisture coming through the below grade parts of the walls. The floor is a concrete slab that's pretty beat up, with cracks and smallish depressions of broken concrete here and there. I was in a rush when I was finishing it and just threw down 3/4" thick rubber mats from Tractor Supply (with coin-sized dimples on the underside to conceivably allow airflow). Garage also has a mini split and ceiling fan for heating/cooling and air flow. My problem: I now have a fair bit of moisture build up under the rubber mats and what appears to be mildew (hopefully not mold?). What's the best way to deal with this? I'm considering trying to get a bit more insulation on the floor, something like dricore subfloor panels (not the OSB ones, the purple ones) to put under the rubber mats. I'm assuming the moisture is coming up through the concrete though. Should I fill all the cracks/pits and seal first? Money is an option, don't want to spend an arm and a leg to fix this, but also don't think its a good idea to let this fester for a long time. I live in Spokane, WA, fairly cold/wettish winters, dry/hot summers. Thoughts? submitted by /u/because-i-said-so-1 [link] [comments]

Mar 16, 2025 - 17:55

Here's my situation: I have an approximately 400sqft garage that I converted to a gym/workshop. Spray foam insulation on walls and under roof deck (no false ceiling, open to the rafters). It's built on a slope, south wall is about 4 feet below grade, north wall is the garage door that is on grade. I don't have any moisture coming through the below grade parts of the walls. The floor is a concrete slab that's pretty beat up, with cracks and smallish depressions of broken concrete here and there. I was in a rush when I was finishing it and just threw down 3/4" thick rubber mats from Tractor Supply (with coin-sized dimples on the underside to conceivably allow airflow). Garage also has a mini split and ceiling fan for heating/cooling and air flow.

My problem: I now have a fair bit of moisture build up under the rubber mats and what appears to be mildew (hopefully not mold?). What's the best way to deal with this? I'm considering trying to get a bit more insulation on the floor, something like dricore subfloor panels (not the OSB ones, the purple ones) to put under the rubber mats. I'm assuming the moisture is coming up through the concrete though. Should I fill all the cracks/pits and seal first? Money is an option, don't want to spend an arm and a leg to fix this, but also don't think its a good idea to let this fester for a long time.

I live in Spokane, WA, fairly cold/wettish winters, dry/hot summers. Thoughts?

submitted by /u/because-i-said-so-1
[link] [comments]