concrete hell #2

Previously I wrote about the joy of discovering, after wrestling with flooring choices, that we appear to have a good chunk of moisture coming up from underneath the slab along the outside walls in our back bedroom.

Still not sure what to do about this, I try a couple of things.

First, I try turning off the window fan in this room; we had it going in here constantly due to the drywall compound, paint, etc. that was being used in this room. At this point, though, there isn’t anything outgassing that we know of, so I figure maybe the fan is lowering the air pressure in the room enough that it’s drawing moisture up through the concrete. So I try turning it off.

Second, I rent a jackhammer:


Not that I’m the destructive type, of course. I didn’t actually want to rent the jackhammer, of course. }:> .

It turns out that the chowderheads who put in the back patio, among other things, did it wrong. Either that, or the slope of the yard changed between when they put it in and when we got the house.

In three different places, the back patio concrete butts up right against the drip edge of the stucco wall. There’s no gap at all — it just touches and appears to seal it. And of course, in both of these places, due to the slope of the patio, water puddles up when it rains and sits against the house wall.

None appears to actually get inside the house, fortunately, but it does appear to moisten the foundation slab, from what I can tell. (When the floor was wet from the original roof leak that started all this, since the water came down inside the walls, I had originally thought that this patio water was the source of the water in two different rooms when it rained. Turned out it was the roof; this season those rooms stayed dry. YAY.)

So, I went to Home Depot and rented the jackhammer for four hours. I started on the patio at the corner of the house, busting concrete away to about four inches from the house wall and slab edge. This went a lot easier than I thought; I set up the jackhammer like the people at Home Depot showed me, and basically used it to chisel away bits of concrete, a lot like the air hammer did with the stucco on the windows a while ago.

After a little bit of work, I discovered the previous patio:


Apparently the current patio had been installed right on top of the old one. No rebar or anything. You can see the used-to-be-exposed foundation under the drip cap edge of the stucco wall. The new concrete had been poured right up against that edge of the foundation; fortunately for me they hadn’t cleaned the foundation edge before pouring, otherwise the patio chunks wouldn’t have come away as cleanly.

I finished this section, then jackhammered a trench in the middle of the patio where the water would pool, so that it would at least not collect on top of the patio and puddle up near the house. As a result I also now own four traffic cones (which you can also purchase at Home Depot).


The next time it rained, both these solutions seemed to work well. Water didn’t collect up against the house and wall drip cap edge, and it didn’t puddle in the center of the patio as much as it used to. (Still a little bit, but not nearly as much.)

Unfortunately, the efflorescence came back yet again. So these attempts didn’t work. I could have just said screw it and put down the underlayment and flooring, but I didn’t want to have water pooling underneath the moisture barrier.

As a (hopefully last) resort, I’ve called in a structural engineer. For about $650, he’s going to do a full report of recommendations for what to do to try and resolve this problem. This includes doing the calcium-chloride moisture transmission tests (fill a container with calcium chloride crystals, weigh it, put that container under a pie tin sealed to the concrete slab, and 72 hours later undo the pie tin and weigh the container again, and from that calculate the pounds per hour moisture transmission value), and also doing a scraping of the adhesive to see if it really does contain asbestos.

On that last bit, it turns out that we never actually had the adhesive tested, just the tiles. The engineer said that usually if the adhesive contains asbestos it’s gray, and ours is black. So there’s a chance that it doesn’t actually contain asbestos, and we might be able to have any company do the scarifying so we can seal and use the original bamboo flooring. (Which might be a good thing, as it looks like ifloor no longer carries the color of the click-lock bamboo flooring I bought a single box of. Sigh.) And sealing the concrete should take care of the efflorescence, as well.

The other part of the engineer’s recommendations are probably going to include redoing the concrete walks and patio around the house. I was already mostly expecting to do this due to the drainage and pond issue mentioned in concrete hell #1, so that we could install a real PVC underground drainage system that goes out to the street, and it sounds like doing that, as well as re-laying the concrete or other ground cover with a slope away from the house, and properly sealing the crack between the foundation and this concrete walk should help resolve this moisture issue.

He also confirmed my fear about water puddling underneath the moisture barrier; he said he’s seen gymnasiums where the wood floor bubbles because of trapped water underneath the moisture barrier.

So we’ll see what happens when I get the report back. House joy never ends, I tell you…