Lots of water under my house
January 30, 2017 12:36 PM   Subscribe

We bought our house during the drought (California) and even then, every contractor who went underneath remarked on our unfinished crawlspace's wetness. Now we've had record rains and the hardwood floors in our living room just started buckling, apparently (to me) from moisture. Who can solve this?

We need a total foundation replacement for other reasons, but that costs 40 thousand dollars, so not really rushing into that (praying for no earthquakes). Can I, a game but inexperienced, mildly handy person, just somehow install this thing I keep hearing about called a "sump pump"? Or do I need to hire a... plumber? To create some kind of drainage system? Running along one side of our house, and connecting to the house foundation, is a cement driveway, which I want to remove anyway, and which one contractor suggested we remove in order to dig a french drain next to the house...

Basically, I know the goal is replacement of the foundation with full mitigation of moisture and installation of adequate drainage, but in the mean time, what can I do myself, or hire a contractor to address over a day or two that might make a difference?

Crawlspace is very low, dirty, and yes, very wet (I'm afraid to see how wet), but I can get in there.

I am game to do stuff myself but know nothing.

I know we might all die in a fricken' nuclear holocaust before this becomes a real issue anyway, but I need some stuff to do on weekends besides go to Trump protests.
posted by latkes to Home & Garden (14 answers total) 4 users marked this as a favorite
You can dig a french drain, or have someone do it for you, all around the perimeter of your house for much less than $40K. That's probably a good place to start before you tackle a sump pump. If your french drain significantly reduces that amount of water making it into the crawlspace, all the better. If not, you know you have deeper issues than surface drainage.

We were faced with foundation replacement but were able to get the city to approve a sort of half-replacement: we're on a slope, so all the force rests on the front of the house. We did a really solid rebuild of the front 1/3 of the foundation instead of the entire thing. In the process, we put in a really solid french drain along the upslope-facing sides of the house, including along a long stretch of the rebuilt foundation. We no longer have water streaming under our house because of that drain, hooray.

We also have a wet crawlspace, but no sump pump. Instead, we have a passive drain that connects right to the sewer. Can you check into something like that, if you don't already have one? It's possible there's an existing drain that needs to be repaired, brought up to code, or otherwise optimized.
posted by late afternoon dreaming hotel at 12:53 PM on January 30, 2017 [4 favorites]

This is mostly beyond me and it seems like a big problem so I hope you get some help! We live in a wet area with clay soil and a rain garden really helped. We still had to deal with structural issues, but it gave the water coming off of our roof somewhere far away from the house to go and drain. Coupled with a rain barrel, it meant a lot less water was available to seep into a our basement. Fill it with local plants and a year or two in it will mostly take care of itself. Good luck!
posted by Bistyfrass at 12:58 PM on January 30, 2017

North SF bay, California here, on pretty clay heavy soil. We have crawl space, and a sump pump under the house, it runs regularly in the winter.

Sump pump: Find the lowest area in the crawl space. Dig a hole. Drill small holes around the outside of a large bucket or washtub. Put a small layer of gravel in the bottom of the hole, wrap the bucket in a fairly fine mesh or screen, insert the bucket in the hole, fill around the bucket with gravel.

Insert the sump pump into the bucket. Plug into a GFCI socket. You can probably find better instructions in the interwebs, but it's not complex. Home inspectors who see sump pumps will give you a grand spiel about how the homeowner who did this was incompetent because what they should have done was... and then you start to dig into the replacement and discover that they did exactly what the home inspector said they should have done...

The other two things that did amazing things for our house comfort:
  1. Two layers of 6 mil plastic directly on the dirt, taped around the edges to the foundation. We were quoted $4.5k to do this with 20 mil plastic, which would have been nicer and may have been worth it, but it's done now.
  2. Insulate between the joists up against the floor board. Prefer unfaced insulation.
Did these things and our 1947 cottage was very much more comfortable.
posted by straw at 1:07 PM on January 30, 2017 [6 favorites]

I agree that the sump pump is the best option until you can install a passive draining system.
posted by Midnight Skulker at 1:45 PM on January 30, 2017

Considering that your crawlspace was wet even during the drought: are you sure you have no plumbing leaks?

There ought to be some kind of vapour barrier between your open-to-the-air crawlspace and your floor; it sounds like this is another thing to try to check.
posted by heatherlogan at 2:06 PM on January 30, 2017 [3 favorites]

Check to see what your downspouts are doing with the water. Just dumping it on the ground near your foundation is always a bad idea.

Polyethylene lain down on the ground in your crawlspace can greatly reduce the movement of moisture from the ground to the air in your crawlspace.

Depending on where you are in California, you might be able to address the problem with improved crawlspace ventilation, to reduce the humidity in the crawlspace. Ventilation is counterindicated if the humidity is every high enough outside and your crawlspace is ever cool enough to allow condensation, however.

"..dig a french drain, or have someone do it for you, all around the perimeter of your house..."

Be a little careful here. If you have a perimeter foundation, and you dig too close and/or too deep, you can destabilize it.
posted by the Real Dan at 2:17 PM on January 30, 2017 [1 favorite]

sump pump basin. you might need to drill holes to allow water to flow in.
posted by H21 at 2:22 PM on January 30, 2017

I have a similar problem in the bay area. I think the best solution is making sure the ground next to your house is properly graded and moving downspouts to ensure water goes away from the house properly. That should be sufficient as the ground is pretty impermeable otherwise and I don't think the water table is really an issue liek it in in regions where sump pumps and basement are a thing.
posted by GuyZero at 2:23 PM on January 30, 2017

Oh and: you probably want a couple of layers of landscape cloth between the diet and the gravel. You're trying to create a filter to keep dirt from the pump.

Also, don't tie the pipe from the pump to the floor joists: it will transmit the noises from the pipe right into the floor. Isolate it: hang it, run it along the ground and only go up when you get to the vent where you're exciting the crawl space: something...
posted by straw at 2:41 PM on January 30, 2017

1) your crawl space needs to be either ventilated or conditioned. If your local relative humidity levels are high such that ventilation is counterproductive but you don't use air conditioning then installing a dehumidifier in the crawlspace will mitigate the high humidity that is warping your floors

2) installing a vapour barrierover the dirt will prevent migration of vapour from the ground into the house structure. Plastic sheeting is the normal method. Use the black stuff rather than the clear. Best results will be obtained if the sheeting is sealed (acoustical sealant) to all penetrations and to the foundation wall with all seams taped (we'd use tuck tape but Americans have something else). However even just rolling the sheeting out will greatly reduce transmission as the transmission is governed by exposed surface area.

3) if you have standing water or if a dug 5 gallon bucket sized hole collects standing water then installing a sump pump will help. Otherwise it is a waste of time and money.

4) make sure water is directed away from your foundation. Clean gutters. Direct downspouts well away from the foundation. Regrade ground that encourages water flow to the building instead of away.

PS: NEC calls for sump pumps to be GFCI protected. Canadian code allows dedicated sump pump receptacles to not be GFCI protected because a nuance trip won't be detected till the high water is noticed. Either way the risk of shock from a sump installed in a crawlspace is very low.

PPS: if you haven't been in there since your floors started warping be prepared for mold and mushrooms.
posted by Mitheral at 2:56 PM on January 30, 2017 [1 favorite]

Southern Cal here. We have some buckling in the hardwoods on the second floor. (I bet you are jealous of our master bedroom skateboard ramp!) Our buckling is caused by a window that was poorly installed and water leaked in the wall. Back in the drought, we didn't know. After the December/January rain, now we know.

All this to say, don't assume it's your crawlspace. You really do need to figure out where the water is getting in and under the floor. Did the buckling start by a wall? Look for rippled trim - that's your contact point. Before you start doing the hard labor, identify the issue.
posted by 26.2 at 4:44 PM on January 30, 2017 [2 favorites]

With water damage and potential for mold, you should really also call your homeowner's insurance and get them involved in the repair. Not doing so can impact your policy.
posted by quince at 5:04 PM on January 30, 2017

The contractor you'd want is called a "basement contractor" or "basement water contractor" ... they run ads here pretty frequently. (If you still get the yellow pages this is a good use for it, looking up the class of contractors.) Most will say in their ads or on the web that they do crawl spaces. Have a few out for quotes. I had to have my whole basement jackhammered out 6" from every wall to install new dewatering systems and a new sump pump, and it came in under $5000. Sounds like your needs are simpler than mine. Have a couple-three places out for proposals and quotes; we found considerable variance in what they thought needed doing and how much they said it'd cost us. But we came away with a real clear idea of what we wanted done and what we were willing to pay.
posted by Eyebrows McGee at 11:25 PM on January 30, 2017 [1 favorite]

Late to the party, but I had this problem, too. Very high moisture in my crawlspace, in one part the dirt was nearly to the floor joists. It was a very expensive issue to fix -- in the tens of thousands.

The first thing was fixing the drainage on my property and making sure no water could get in there again. This included a road base filled trench around the entire perimeter of the house as well as grading. Then they encapsulated the crawlspace completely with super heavy duty plastic. It's real nice down there now, with lights/electricity and a dehumidifier that runs "as needed" but it's pretty much all the time. Feel free to Mefi mail me, it took me a long time to find a contractor to do this work.
posted by theRussian at 8:31 PM on February 6, 2017 [1 favorite]

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