Mold remediation - I think stachybotrys

[Ashful]

Good suggestions, although I'd make two others:

1. You may not want to glue the lid onto the sump pump. Just placing it there should do the same job, and you'll be kicking yourself the first time you want to get in there to check something, if you glue it in place.

2. Check with your local swimming pool suppliers. They should have a rubberized gap filler for pool decks, available in larger containers. A standard caulk tube is 10 oz. The larger one you're discussing is 29 oz. = 52 cu.in. Now figure your gap is likely 2" wide, and you'll be filling "an inch below the floor". So, 2 cubic inches per linear inch... or one large tube of caulk per 2 feet of perimeter! You can buy this caulk in 1 or 5 gallon buckets from a pool supply house.

 

[velvetfoot]

They might have used another PL product that is polyurethane caulk. I bought some at HD a while ago. It also comes in self-leveling. Both made for sealing concrete cracks.

I found my basement was less stinky after insulating the walls with extruded polystyrene foam, and covering with sheetrock; less area to condense. Still nothing on floor though.

I have an electronic radon detector by Safety Siren (~$120). You can turn off the fan or do some other mods and and see how that affects the radon level.

 

[midwestcoast]

... Now figure your gap is likely 2" wide, and you'll be filling "an inch below the floor". So, 2 cubic inches per linear inch... or one large tube of caulk per 2 feet of perimeter! You can buy this caulk in 1 or 5 gallon buckets from a pool supply house.

That's why the guy he was talking to suggested stuffing backer rod in first. Way less $ than using all that caulk. Also most caulk won't hold in gaps anywhere near that wide without backer rod.
Sounds like a good plan to me

 

[Ashful]

That's why the guy he was talking to suggested stuffing backer rod in first. Way less $ than using all that caulk. Also most caulk won't hold in gaps anywhere near that wide without backer rod.
Sounds like a good plan to me

Yeah, but my numbers were WITH the backer rod, assuming he puts it 1" below floor, as suggested. Without the backer rod, and assuming that trench is at least 4" deep, he'd be using two 29 oz. tubes per foot!

 

[woodgeek]

So you think all the water is coming in in vapor form through the gap around the floating slab? Just don't see it. I still think its the sill/rim, or maybe coming through the concrete walls/floor in vapor form.

 

[midwestcoast]

Yeah, but my numbers were WITH the back rod, assuming he put's it 1" below floor, as suggested. Without the backer rod, and assuming that trench is at least 4" deep, he'd be using two 29 oz. tubes per foot!

Thanks, I read it too fast. I wonder why the guy told him an inch down? seems like way more than enough to hold the caulk in place. I'd say he could get it more like a half inch below, just leave the caulk level below the slab, or even just run a bead on either side of the backer rod the seal the edges. The 2 edges are the only place the caulk is doing anything anyway (assuming the rod is closed cell foam).

 

[mywaynow]

If you get to paint stage, use a test area first to make certain the humidity in the floor/wall is not too much for the adhesion/curing. I just saw what that looks like and it is not pretty. Old garage floor that got very wet and was epoxy painted before the levels were good. Created bubbles and fisheyes in the surface and now must be ground off.

FWIW, I did flood cleanup with 50/50 water and bleach to deal with mold. It worked great and I was never concerned with the possibility of fire (alcohol).

 

[Ashful]

So you think all the water is coming in in vapor form through the gap around the floating slab? Just don't see it. I still think its the sill/rim, or maybe coming through the concrete walls/floor in vapor form.

I agree. As stated earlier, this is almost always an issue of outside air infiltration. However, I also don't see how sealing the perimeter and sump pit can hurt.

Me? I'd stuff the backer rod in the gap, and skip the caulk. See what kind of difference it makes, and what potential problems it causes, before making it permanent. Backer rod is easily removed, caulk isn't.

If he has (or plans to install) a sub-slab radon system, then the perimeter gap is much less relevant with respect to moisture problems.