Waterproofing the basement!

[Juddog]

Yeah, for my place half the house was properly waterproofed, but the other half wasn't. (I have a big house, and it was built in stages.)

In the non-waterproofed side, I had moisture and mold issues. I had to run a dehumidifier most of the day during the summer to remove moisture in the basement, or else it'd sometimes start to smell a bit like mold.

So, when I did my basement interior reno, we cracked the slab and dug down to put 6 inches of crushed stone for drainage, with 6 inches of cement on top of that. Before it was 2-4" of slab on top of soil, so my moisture issues were actually coming from there, not leakage from the walls.

However, I did note also that the wall was moist in a couple of spots near downspouts from the eavestroughs, but got no flooding ever from these non-waterproofed walls. I've since redirected the downspouts with success. Nonetheless I still wondered about the cost for getting the place properly waterproofed exteriorly. The quotes came in at $12000 - $15000 CAD IIRC, which is only slightly less in US $.

However, a third guy (from the biggest company of the three) came in and suggested I do NOT get it exterior waterproofed since the slab redo and downspout redirect solved my problems and I haven't had any moisture issues since, even after heavy rainfalls. I took his advice and didn't bother, and it's been fine. I don't have to use a dehumidifier in the basement anymore, and there are no longer any mold issues either. After the foundation fix, it's as dry as the rest of the house (according to humidistats).

Oh yeah, we had some moisture retardant paint we used on the interior cinderblock, but I'm convinced it's near useless. However, it can't hurt, so I said to the basement contractor to go ahead with it.

Oh and I have a backflow valve on my main sewer line, since the rain runoff in my city flows into the sewers, which causes a lot of problems with sewer backups in the city. It looks like this, but it's not clear:

http://www.youtube.com/watch?v=FMBznnNV-ss

How much was the slab redo, and did it increase / decrease the depth of the basement in proportion to where it was before?

 

[Eug]

How much was the slab redo, and did it increase / decrease the depth of the basement in proportion to where it was before?

Many thousands of bux, but I don't remember the exact amount off hand. They had to do everything by hand, including pouring the foundation, as we were living in the house at the time and there was no way to get the heavy machinery in there.

I did not increase the depth of the basement, as that would have required much more extensive work including underpinning. It would have also probably cost me $40000 or more. Plus in my neighbourhood, underground streams are fairly common. My basement is short, but tall enough to be within code (unlike some basements in the city), and it's not so bad for me since I'm not tall to begin with. Still, another foot deeper would have been nice. Then again, maybe not. At the back the windows are at chest height. If we dug down another foot, they'd be harder to see out of.

The contractor told me he had lowered many basements before (with city approval) with great success, and hadn't had a problem yet in my city with underground streams, but admitted it could be an issue. So I told him that it's a big problem in my neighbourhood. He consulted with a colleague friend who knows more about the local geography in the city and after that agreed with me it would be a bad idea in my neighbourhood.

 

[Jeff7]

$10k is an estimate for a fair sized house and assumes waterproofing the basement walls with the appropriate materials in addition to installing the french drain. I know someone that did it for about $800 in materials, but they knew a bunch of people that basically worked for free to help them out, and had access to construction equipment to dig it out.

Other methods include digging a trench and pouring in roofing tar, mentioned in the other waterproofing thread by a forum member, which forms a humongous rubber seal. It all depends on who you know, what kind of equipment you have access to, etc..

Ah, all that other stuff would certainly add to cost.

There was no coating done at my parents' house, it was just digging a trench, laying down some pipe and crushed stone, filling it in, compressing and leveling it, and leaving.
I'd say that they did a pretty good job of it, considering the results.

 

[Eug]

Ah, all that other stuff would certainly add to cost.

There was no coating done at my parents' house, it was just digging a trench, laying down some pipe and crushed stone, filling it in, compressing and leveling it, and leaving.
I'd say that they did a pretty good job of it, considering the results.

If you're gonna dig a trench, you may as well seal the side of the house. No, the seals aren't perfect, but they do help of course.

 

[Jeff7]

If you're gonna dig a trench, you may as well seal the side of the house. No, the seals aren't perfect, but they do help of course.

True, but unfortunately for that, this trench wasn't right against the house, it was several feet away. I think it was mainly to give water a way to get around the house, rather than building up pressure and forcing its way in through the concrete.

It would come in through the walls and floor at a pretty decent flow rate, like it had a nice head of pressure behind it. And when I say "sloping toward the house," as an example, on the front of the house, the short and steep driveway went up toward the road, rising about 15 feet higher than the house.

Just giving the water an easier route took care of the problems we were seeing. Still probably not ideal, but it at least meant an end to the basement flooding that occurred every few years.

When there was flooding like that, the cats were usually the ones to let us know in the morning that something had gone wrong during the night. They'd be slowly walking around near the top of the basement stairwell, acting rather confused and looking up to us for help: Their litterboxes, dry food dish, and water dish were all downstairs.

 

[KaOTiK]

Put a LARGE drain in the floor. With an industrial garbage disposal in it. It really helps with clean up.

 

[Zee]

First of all, kudos to you for making me come out of "Lurker" status.

I just had my unfinished basement waterproofed by professionals. We have a sump pump but were still getting water in via the previous owners french drains / foundation wall cracks (1950's house) / window wells.

They dug around the exterior and put tar / plastic below grade. Tile was also placed around the exterior and connected to the interior system. Interior was jack hammered and they replaced the foundation tile and added a second sump pump pit (and battery backup). Interior wall cracks were injected with a sealant.

This was for our particular area. High clay soil. Basically the house sits in a bowl where water collected. After we had it done we learned from some people a creek ran through our neighborhood at one point. Another neighbor didn't have any success until they did both the exterior and the interior like was done in our house.

Ours is warranted for as long as we own our house plus it can be transferred. They started with a crew of 4 on a Monday, crew of 6 on Tue - Thurs, and finished on Friday with a crew of 10. Ours was a lot more labor intensive than they anticipated. Plus due to footage they had to add a second sump pump pit. I was told 1 pit can service 170' of wall. Ours was 174'.

Our basement walls were painted with that stuff but it is peeling off in several places. Yeah it was expensive but if we ever have issues again it won't cost us a dime.

until they go out of business or close and set up a new shop intentionally

 

[Red Squirrel]

If you're gonna dig a trench, you may as well seal the side of the house. No, the seals aren't perfect, but they do help of course.

Yeah definitely. The weeping tile is only half of the water mitigation system. If the wall is not sealed up properly does not matter how good the weeper is, you'll have trouble.