Water in my crawl space: how best to drain it?

[inveresk]

Just seen your crawl space photographs. The problem, rightly identified by you and others, is that the crawl space is way too deep, so much so it's below the water table for part of the year. In my view, rhe right solution is fill to take the solum level above the water table at its highest.

This, I believe, is a better solution than trying to install drains around the house to try to locally reduce the water table under it. The crawl space should never have been constructed as deep in the first place.

Curlydave has a good point in that the cripple wall kerb will be too low if you add fill. I can't see from the photograph if the cripple wall is simply supporting your floor joists mid span or whether it's a shear wall. If it has ply on the other side, it's a shear wall and you'll need a professionally designed solution to ensure structural continuity as likely it's a shear wall above too. If there's no ply, it's not a shear wall.

I'd consider taking out the cripple wall altogether and replacing it with steel posts and beams to support the joists. Labourwise, prefabricating them in manageable lengths to mandhandle down the hatch, with bolted connections and the posts in turn anchor bolted onto the kerb, would be a fairly quick install with no wet trades. If you needed the steel posts and beams to have shear resistance, you could shot fire ply one side.

This, too, should be a professionally designed solution to take account of your loads, spans and local building codes and to keep you on the right side of your lender, house insurer and, when it comes time to sell, all relevant codes and regulations.

Your going to need quite a quantity of upfill. Rather than navigate steps and traffic wheel barrows through the house to the location of the hatch, it might be worth considering. cutting a larger temporary opening at the vents, maybe more than one, and chuting the fill in from the perimeter so you can rake it around.

 

[Paddy]

I think this whole discussion of filling the crawl is missing the point. With a working perimiter drain, he could have a bacement. What good would it do to add 12" -24" of fill other than a lot work moving dirt on your hands and knees? If you had a boat with a hole, would you install a larger pump or fix the leak? This house has a few design flaws, non working drain and a wood wall in the crawl that does not have suficiet clearence from the dirt. These issue need fixed, every thing else are just bandages that might not help.

Let's quantify the the back fill. 1600 sq ft by 1 ft of fill= 1600 cubic ft of dirt or 59 yards of fill!! At 24" 118 yards!! can you imagine moving 3 large dump trucks of fill (12" fill) let alone 6 large trucks.

Filling would cost far more than doing right

Patrick

 

[inveresk]

To convert it into a watertight basement is certainly an option but from the photographs and using assumed joist spacing at 16" c/s as a gauge, I estimated the clear height at around 4'. Even dry, it remains a crawl space that you can't stand up in and that you access through a floor hatch and down a ladder. I question how much more useful that is than a shallower crawl space that doesn't involve emasculating the landscaping to make dry.

I think a more appropriate analogy to the hole in the boat is to make a comparison with a house on a tidal plain. If the water laps at the threshold every time the tide comes in, are you better diverting and damming the water or raising the affected parts of the house out of it?

Clearly there are different ways to go about solving the problem and more than one of them would work but whichever one is adopted needs the sanction of a building professional.

 

[Highbeam]

It wouldn't be disclosed because it is new construction and hasn't been a problem. You give the builder too much credit to be honest and proactive about these things.

"If he built the house he must have prints someplace. The prints would tell him if drains are inside and outside the footings."

There will be some kind of print with lots of typical details. BUT, that has little to do with what is actually built. I have no less than 10 single family residents on my desk to approve and the architects that drew up the plans seem to think that their job ends at the downspout. The drainage between the downspout and the ditch is a field decision. Our building official claims that once the storm pipe goes horizontal that he is no longer responsible, this is how the downspouts and footing drains so often get done half-a$$ed, they fall in the middle of two inspectors with neither claiming responsibility.

 

[Parttimer]

Most of the replies have good suggestions in them. But...... get all the facts. Dig down and locate the drains to verify elevation, take some elevations around the yard. Speak to a "local" Civil Engineer who specializes in drainage, most deal with drainage as a large part of their job. The engineer will take into account all of which has been spoken here and give you their best choice.

On the issue of mold, vapor barrier, (6 mil. poly barrier overlapped, along with what looks like plenty of ventalation (which can be verified with the engineer for code adherence) should protect your house. You are not going to stop all of the vapor/moisture, but that is what the vents are for.


Dave

ps. there sure are alot of engineers out there.

 

[RFB]

The house is fairly "new" to him, and if he is the first owner, then he has a substantive claim against the builder.

A defect that cannot appear until specific environmental/weather conditions occur (a roof cannot collapse due to inadequate snow load capability until it snows.) could easily toll an initial warranty period. A key consideration for this is prompt notification of the responsible party(s) upon discovery of the problem. The amount of water in his cs is illustrative of poor design/engineering (for the given environment) or poor execution.

The bottom line is that there is a very good possibility that that he really does not "own" this problem, but that it belongs to the contractor. If I were the owner, I would be speaking with an engineer AND an attorney.

 

[inveresk]

I agree, rfb. It might also be worth a formal approach to the builder first, alert him in writing to the problem and ask him for his proposal and a timetable for dealing with it. If he says he's not interested, then the rotweillers in suits can be called in.

 

[Highbeam]

I see your point. Is there any responsibility for investorguy to act in the meantime to prevent further damage?

 

[Investorguy]

I don't know guys. Seeking damages may be wishful thinking. We bought the house "as is" from the first owners who had it built. The inspector knew about the water issue but he said it was no big deal.

If I used Steel supports in place of the wood supports running down the middle of the house, would I not have to build up the concrete?


I talked to an engineer. He was mostly structural and said this was not his area of experties, but he suggested we throw a sump pump in a hole and pump the water out onto the lawn and see how that goes. Of course, that would involve trenching inside the crawl, probably not something I want to do until it dries anyway.

 

[inveresk]

Rather than raise the kerb of the cripple wall, I'd concrete encase the base of the 3 or 4 steel posts that would likely be needed and make sure any exposed steel was properly paint protected.