Garage Help

Old 09-05-18, 10:18 PM
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Garage Help

Hello all
A couple weeks ago we had a lot of rain in the northeast. Our water table rose and I had a small amount of water come through my slab in the basement for the first time. My garage didn't get any water but I'm assuming moisture came through the slab or wall to a point. Now I have about a 8" high ring of black mold around base of the garage block wall. The block has already been painted, I'm assuming with a water-blocking or mold paint? The entire garage is cinderblock backfilled about 5'. Directly above the garage is my living room, dining room and kitchen. The garage door gets sun almost all day so the garage gets extremely hot and humid inside during the summer. I can remove the mold but I would like to solve my heat and humidity problem to prevent issues in the future. I'm looking for ideas to ventilate a completely block garage. I was going to knock some cinderblock out and install some small vent fans?

Ideas are welcome!
Old 09-06-18, 05:04 AM
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I would look to install some type of powered vent/fan on the end wall of the attic before knocking out blocks!

First, they are readily available, many sizes, have louvers and the elec work would be simpler!
Old 09-06-18, 05:20 AM
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Your cement blocks likely have standing water within the hollow cores. If the outside of the blocks have not been waterproofed, that is the source of the water. CMU foundations need to be waterproofed, so if it isn't the wall would need to be excavated, cleaned, and waterproofed so that it does not continue to absorb water that can't escape. When you paint the interior side, the wall can no longer dry to the inside.

Small weep holes could be drilled into the bottom of the block but it's a safe bet that the block goes 4" below your slab floor, so even with weep holes you may have standing water in there. If this was a basement, the solution would be a perimeter drain where the perimeter of the floor is demolished so that a drain can be installed around the perimeter. (Gets ALL the water out of the blocks because the weeps are at the very bottom of the block.) Doubt you want to do all that for a garage.
Old 09-06-18, 05:57 AM
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Hi beer ridge, what is your climate region. What you do is often influenced by where you are.

Note, block foundations have a built in problem when it comes to water ot moisture, they share that moisture side to side. That line you see might represent the water level reached inside those blocks. Although it didn't get through it cooled the inside surface and attracted condensation and then mold. What is going on inside the blocks we can only speculate, likely more mold.

I was typing before I read X's reply, but will leave it.

Another note, with the paint on there it will be difficult to dry out the moisture inside those blocks. Definitely no simple solution.

To demonstrate that one home owners blocks were filled with water I punched a hole near the bottom, it was next to the dump pit and a good thing as the water POURED out for 30 minutes.

One compromise might be a sump pit along the edge of the garage foundation deep enough to bust through the bottom of the wall. You might be able to take advantage of the side to side flow to drain much of that water and collect it in the future before it fills the blocks.

As always, landscaping to shed rain and run-off is always a first step.

Old 09-06-18, 06:09 PM
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Thank you for the ideas so far. My basement is block as well and all on the same level. There's a sump pit and perimeter drain system (I'm told) but no mold issue that I see inside, just the garage. I did have a small amount of standing water come through the floor. Any ventilation recommendations? Punch through the block to add a fan? Not familiar with the attic fan or how to vent it through my block unless you're suggesting cutting a hole in my living room floor to run a vent up to the attic?

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