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

[Highbeam]

I don't think anybody will guarantee that you will not get mold. I feel pretty good about guaranteeing that all homes, especially those in western washington, will have some mold somewhere. There was a time when no vapor barriers were used and crawl space ventilation was much poorer than today. With a 5 foot crawl and a non-floating vapor barrier, you have as good a chance as any to avoid abnormal mold.

They did the right thing to build well above grade in the low area you describe. The trouble is that the footing needs to be on native ground (or engineered compacted fill) so they had to basicly fill around the home to make that mound. They could have then filled in you crawlspace to within 2 feet (code?) of the floor joists. Sand, pea gravel, or even onsite soil a foot deep would have eliminated your visible water problem. I happen to like a deep craw for the sake of walking around and the tradesmen like it for ease of installing ducts, plumbing, and such but you need enough fill to get the grade above your footing drains. That seems to be your problem.

 

[drm]

Investorguy,

Some very good advice so far and I am sure there will be more. On the subject of solutions here is my preliminary take:

1. Get the surface water away, far away like Eddie Walker recommends.

2. Get the ground water away. French drains, sumps, well points are some methods. The most practical will depend on your site conditions and the water table characteristics.

3. “Seal” the moisture off from the inside of the basement. A concrete slab is not required and may cause more problems instead of helping. The surface of the crawl space must be dry. That given and an intact vapor barrier is sufficient. Do not try to “hold it down”. See the concrete slab example below.

4. Mold WILL grow when the air moisture is over 50% and it has a food source (something organic). It CAN start to grow in as little as a few days if it is there and conditions are perfect for it. Mold spores are in the air everywhere so it is only a mater of time before you have problems. This is why it is so scary.

5. An EXPERIENCED engineer whether it is a geotechnical, civil or structural (my preference) is the first person I would go to. I would not spend the money on a home inspection. They are good at looking over the general condition of most of the components and systems in a house but most likely do not have the expertise for this particular problem. You already know that you have a problem, water. Why pay to have someone else tell you this.

The engineer should have experience dealing with this specific type of problem. A geotechnical engineer can give you insight into the underlying topography and the reason for the water. A structural engineer can provide a design that will remove the water and keep you dry.
There will be some that are capable of doing both, but they may be difficult to find. Ask around and call and talk to the individual engineers. Get the engineers that sound like they are capable of solving the problem come out to look at the problem and discuss their course of action. Ask if they would provide a proposal. This project is most likely very small for most engineers and you may not get a proposal but that should not be a problem. Your discussions should give you a feel for them. Like in all lines of work, some people should not attempt to do this work. On the overall scope of things the engineering fee will be minor compared to not doing the work right the first time.

Here is a little personal experience:
I grew up in a hilly area of PA and had water in the basement several times. Regrading a hillside that had originally drained straight down to the house solved that problem.
Bought a house in an urban area of Chicago away from any of rivers and never though about ground water. There were no runoff problems, but; during a rather wet spring I had water in my basement. We had overhead drains so it was not coming from the sewers, thankfully. It came through the many tiny cracks in the concrete basement slab. I had dozens of small fountains of water, up to 12” high, shooting up thru the cracks.
The solution was to provide a sump pit and pump that acted as a well point to lower the ground water under the slab during unusually wet times. We had a couple of near/record breaking rains after that one and no problems. The well point was just a sump pit with an open gravel bottom and a sump pump to pump out the water. One time the pump ran continuously for a couple of days but the basement remained dry.
Also, I made sure I pulled the pump and thoroughly cleaned the dirt out of it and the pit before each spring.

…Derek

 

[drm]

Highbeam,

Not sure why you CE’s don’t care for us AE’s. Is it because we get all the fancy jobs doing the classy buildings and you guys are just pumping poop? /forums/images/graemlins/wink.gif

Just kidding. I have done my fair share of both; quite a few pumping stations and such around here. Not sure of the AE programs out that way, but, here although they are independent of the CE program they are 95% engineering and just 5% architecture. Just enough to confirm why engineers and architects don’t get along.

Worked in the Midwest for 10 years and billed myself as a structural engineer because they did not know what an AE was. Kept thinking I was an architect. Can’t draw my way out of a paper bag but can design 10 ways to get out, over, or through it. Looked into an MS at U of Ill and found out I had taken the majority of their graduate classes in my fifth year of the AE program.

…Derek

 

[inveresk]

Can I suggest there are two approaches to resolve the problem of water ingress. The first is to tackle the job from the outside but this isn't always possible. I had one project in which vaulted stone cellars under a sidewalk in a city centre bank built around 1820 were leaking. We'd no option but to waterproof from the inside and it was done successfully and at reasonable cost.

By all means look at additional curtain drains, french drains, diversionary ditches, changing the water table etc. etc. as recommended by others in the thread but at the same time, why not consult some of the companies in your area that specialise in waterproofing basements/cellars? Ask three, say, to inspect your crawl space and then to submit a model spec. and a quotation for solving the problem. Try to use companies that offer an insurance backed guarantee.

Incidentally, on the bank building the waterproofing contractor used a sand/cement render coating with a non-hygroscopic additive. It worked well. Another material I've used is heavy duty (10#) torch on felt tanking. Asphalt tanking would work equally as well but would likely be more expensive. The base needs to be dry to apply both of these so you'd have to wait until the basement dries out.

I re-read the original posting and now realise you don't have a slab. This won't work without a slab. You have no option but to try to solve the problem from the outside.

 

[CurlyDave]

it was built up on a mound of fill.

Send pictures, especially one that shows the height of the mound of fill compared to the natural surface of the land. If you are high enough up, this problem is going to be a lot easier than if you are not.

One thing I've started doing is NOT putting in those styrafoam foundation vent blockers. I pay a higher heat bill, but I keep plenty of ventilation all year round.

This is more a question to the Architectural and Civil Engineers on the thread. It seems to me that filling the spaces between the floor joists with insulation, with the vapor barrier side of the insulation down, would both save on heating, and keep any moisture in the crawl space which gets above the primary vapor barier from rising above the floor joists. This should confine any potential mold problem to the crawl space where I presume there would only be posts and beams, instead of the entire house to worry about. The possibliity of mold on the posts and beams is a lot more tractable than mold in the structure of the house.

Any comments guys?

Worse yet, he may have plumbed your downspouts into the footing drain which effectively pumps the roof water into the footing drain and then around your foundation.

Holy Mackeral !! I hadn't even considered that a builder would do something like that, but it is the first thing to check. Make certain that water from the downspouts is collected and drained far away from the house. You mentioned a drainage ditch somewhere -- this is where the downspout water should go. One of the popular things to do in CA is to send the downspout water into an "energy pit" which is a dry well filled with drain rock. Even if you have this type of arrangement, this is nothing more than a method of recharging the ground water level in poorly drained areas and you should get this water into the ditch instead.

We need a picture of your crawl space. If you have piers and posts in there, you need to be certain that the post bottoms are always above the water level.

If the posts are always above the water level you can treat them with something like Tim-bor or Boracare (do a Google search), which will both prevent termites & the like, and help with wood-destroying fungi and mold.

 

[Investorguy]

Here are some pics of the house.

I got home to late (we needed a Costco trip bad) to get good pics of the outside, but I found these I'd taken earlier. Let me know if you'd like a different view.

Also, I'll try to get crawl space pics tomorrow as well.

I do appreciate the help. I'll check the yellow pages for engineers and see what I can find.

Pics (sorry 56kers about the size, but I want you to be able to see everything)

even bigger pics can be viewed here (or if the pics aren't working, go here as well.

 

[CurlyDave]

It looks to me like the main floor of the house is at least 3' above the level of the surrounding land.

The problem should be fixable.

Check out where those downspouts go.

Does that row of tall grass I see in "housefront.jpg" indicate a drainage ditch along the driveway/road?

If it does, there is where the water from the downspouts and your drains should go.

 

[MikeD74T]

Dig an 8" wide trench around the inside of your footing to the bottom of the footing. Put in perforated pipe & a plastic sump. backfill trench with 3/4" stone. Pump the water out to the ditch along the road. DO NOT CONNECT TO THE DRAIN OUTSIDE YOUR FOUNDATION!

I've poured several acres of concrete floors. The biggest problem you are likely to encounter is soil that swells when it's wet. It lifts the slab which then cracks. If you don't have any reason to get in the crawl space regularly leave it dirt with the poly. Sump pumps are the norm in seacoast New Hampshire. I guarantee it will work for you. If you get water during the freezing months you must route the hose or pipe from the pump such that it drains completely when the pump stops.

 

[Highbeam]

Ah yes, the bottom line. You've got water in your crawl because the water table is higher than the crawl floor (or the off chance that the grading/downspouts/footing drain are botched). I am feeling pretty certain it is the water table judging by the pictures and apparent detail of construction.

Your builder looks like he was smart enough to put the finish floor well above existing grade but he had to dig quite a ways to find good solid material for a footing to set on. You have a tall house above a deep hole. Very nice place by the way.

If it were my home the permanent solution would be to collect the vapor barrier into a pile, dig a pit for a sump pump chamber in an apparent low spot, and then from this pit run shallow 6" ditches around the crawlspace permiter and to any apparent low spots just large enough to lay an inch or two of gravel, a 4" perforated PVC drain pipe, and then surround the pipe with gravel. A bit of slope on this drain pipe wouldn't hurt at all. The sump pump should dicharge through the stem wall, use a rotohammer, and all the way to the ditch. Spread the trench spoils between the trenches in such a manner as to direct water to the trenches and then respread the vapor barrier. Hard wire the sump pump so it is always on. This will stop the floating vapor barrier and solve the problem. The next step for a 100% guarantee is to pump in gravel through a vent and spread it level to hold the vapor barrier off of any minor surface puddling and allow for surface flow below on top of the dirt but within the gravel. All gravel used is to be washed at the quarry often referred to as clean or washed and of uniform size. Crushed or round is a personal choice. I like crushed myself because it locks together and stays put. All uniform sized rock will have the same amount of airspace 30%.

Of course the above is done after It has been verified that the surface grading outside the home isn't sending runoff towards the foundation and that the downspouts are tightlined to the ditch. The existing footing drain is to be verified and maintained though it will not be used much after the sump pump is on duty.

As an immediate step, you could go down there and feel for the deepest water spot away from the footing, cut an X and peel back the vapor barrier, dig a hole in the muck and water deep enough to drop in a 5 gallon bucket with 1/4" holes drilled on the sides. Set a Home depot sump pump in there and run it's discharge hose through a vent way out into the yard and run an extension cord to power it, keep the cord out of the water. Put back the vapor barrier up to the bucket but don't put it in the bucket to clog up the system. I would do this immediately, the pump can be reused in the permanent solution. You can do it right now. Many of these bucket systems stay in use for decades. My sister even has one with a hole drilled in a bedroom floor below an outlet and a sump pump cord runs up and plugs in.

 

[ByronBob]

I'm with Highbeam. Read above.