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

[EddieWalker]

Pouring that much concrete into the crawlspace sure seems like a last resort solution. What does concrete go for in that area? $100 a yard?? so $3,00 for 30 yards wich will give him around 5 or six inches. Concrete isn't water proof, so it will have to be sealed and then their reinforceing it. Do you tie it into the footings or just float it?

This really seams like a new construction technique that is more like pouring a slab foundation with a crawlspace. Adding it after the fact to the level suggested could easily cost $10,000.

Do we even know that it's a water table problem, or a drainage issue?? Everyone is making the assumption that the water is coming up from hydraulic preasure from the water table. If this is true, how come it's dry part of the year and wet other times? How come his drainage ditch isn't flowing water only 200 plus feet away? He's in the middle of a flat field.

First thing I'd do is check all the drains. I'd even disconnect the downspouts and run them out away from the house a ways with some cheap 4 inch corugated tubing. $30 for a hundred foot roll at Home Depot or Lowes.

Then I'd dig a hole close to the foundation a foot deeper than the crawlspace. Use a shovel if you have to. Just dig a dry hole and see what happens. If it fills up to the leve of the water in your crawlspace, then yes, it's the ground table that's causing your problem. If not, than it's drainage.

Figure out what's going on first.

Address the water problem.

DON'T GO REBUILDING YOUR HOUSE!!!!

KEEP IT SIMPLE!!!!

If it really is a water table issue, than hire a backhoe operator for half a day and have him dig you a trench from your house to the drainage ditch. Get some drain pipe and tunnel under or through your wall. Let gravity do all the work.

Eddie

 

[CurlyDave]

There's no risk of the slab having to come out if you were to add it.

I disagree here. If the slab goes in, and then it turns out that trenches to a sump pump are what is really required, the slab is going to prevent that solution until major parts of it are removed.

You just need a lean mix here, not high strength. You could also order a wetter slump than normal which will help it self level some and you could ask for a retarder to be included so you have more time to work it. Last thing you want here is to have a load of concrete go off on you in the crawl space before you've levelled it. I think to do this job in a day is pushing it.

All the pumpers I have ever used have wanted a minimum of "6-sack, pea gravel" in order to pump. The 7-sack mixes should be closer to waterproof than 6-sack, and are still pumpable.

You definitely would want the wettest slump you can get the mixing plant to give you, and the retarder is a very good idea.

If concrete goes in (a big IF to me), a contractor, who does this for a living, might be able to do 1600 sg ft in one day. As an amateur, I would plan on a crew of 5, and pouring one of the two large areas in a day. If all goes well, do the second large space and the area between the cripple walls a second day, after some experience is gained. That confined space is going make this job a lot more exhausting than you would ever believe.

Everyone in the crawlspace should have the best kneepads you can find. Buy one set and crawl around on them in your living room for a couple of hours. Move some weights back & forth in the living room for a couple of hours, just on your knees, no standing allowed. This will give you a flavor for the job. Some designs of kneepads are constantly coming off, some stay on really well.

We had it inspected, the inspector noted the water. We asked, as part of our offer, for a few grand to fix the problem.

Explain all this to the RE lawyer. You may have a claim against the inspector. Maybe not, it really depends on his report.

The problem is fixable, but it may be a very expensive fix. Unless your FIL is a soils/foundation engineer, get a qualified second opinion, even if it does cause some family strain.

 

[bugstruck]

Mike,

Wow, are you drunk on ideas yet? Lots of assumptions. Can't work a solution on them.

First. Determine the exterior perimeter drain field exists. Then, determine the elevation of the bottom of that drain field relative to the dirt floor.

Second. Do your excavation at a downpout. That way you can determine if/not they are tied into the field. It they are, they have to be rerouted independently. No good viable options.

Third. Get the actual elevation change from the dirt floor to the high water mark in the ditch. Don't care how deep the ditch is.

Finally, confirm the 225' I've seen is the correct distance from the house to the daylight drain opening at the ditch.

There are some things that could be going on to elevate the water table in the vicinity of the house beyond the natural. An elevated drain field with downspouts dumping in doesn't help. Particularly if the bottom of the drain field gravel is at or above the elevation as the inside dirt floor, as many suspect. Again, just speculation.

If you can get those items determined we can offer some solid solutions. Until then, I can't.

Keep in mind your drain field could be properly installed at the perimeter and below the dirt floor. Not impossible and what an improved remedy that would present.

I will tell you an all inside attack on this could be formulated to work well, but I'm not a hands and knees guy. I have more experience at this crap than I dare to recall, but I need an X-ray before I decide to cut.

HTH

 

[inveresk]

Your point to check the drains is well made. There might be problems with them but the fact the the outflow drain runs constantly at this time of year even in dry spells suggests what we're dealing with is a seasonlly high water table, common in this area where half our annual rain falls between November and January.

Your also right about the concrete. The fill doesn't need to be concrete. All we need to do is add bulk to get the solum above the seasonally high water table. Gravel, sand, or other fill materials would do the job just as well, provided the solum is not in standing water as this will raise the moisture content even with the ventilation provided. I'd be inclined to top the fill with some sort of slab though. As it's not structural it doesn't need to be reinforced or tied into the kerbs. The advantage I see concrete offering is that it will be able to be pumped which I doubt the other materials could, which should make distribution and levelling easier.

If you consider a sump pump as an active system to resolve the problem, raising the solum is a passive solution. By and large, house construction using passive systems rather than active are less liable to go wrong and are cheaper to run for the simple reason there are no pumps, electricity dependent components, etc. For this reason, I puruse passive solutions rather than active as a fundamental design principal whenever I can but in this instance there is a capital cost penalty for adopting it.

Concrete will likely be considerably more expensive than a sump and there are logistial issues in installing it. Whether an active or a passive solution to this problem is chosen, however, is not a decision that the engineer should make but the client. If he client's instruction to me as a designer is to come up with a passive engineering solution to water ingress, namely a solution that doesn't rely on pumps or other electrical components, then it's my job to respond to that brief.

In this instance, I'd have no hesitation in endorsing concrete fill as a sound professional solution. I also have no doubt that, given one or two prudent precautions, it will be 100% successful. It won't be the cheapest option and it involves a lot of hard work but it will result in a dry crawl space that will stay that way given power cuts or pump failures.

 

[Parttimer]

If you are going to fill the crawl space in with stone then concrete, please use a vapor barrier below the concrete poured and a welded wire mesh and or fiber reinforced concrete to prevent cracking during the curing process. also you may want to consider placing a plastic sump pit in a conveniant location with a cover, just in case you get an unusually high water table. You would then be able to throw a sump pump in the bucket and pump your own crawl space out, "if" you needed to. Remember water will most likely "not" be kept out by the cement if the water table gets to be higher than the slab elevation. Creating a water proof solution is an expensive undertaking, I have designed and built some near wetlands in my area. Remember, I still stand by locating a registered PE in civil engineering in your area familiar with your local codes and regulations and soil/climate conditions.

advice is great, but verify yourself.

dave

 

[bugstruck]

At risk of agitation where none is intended, can we park the concrete solution momentarily? I'm not even saying you, I and, Mike himself won't land there eventually, but at this stage I see more argument against than for. If the foundation area water table can be lowered through capture via active or passive managment the need for gravel, sand, and concrete on the interior could be mute. I think we all would agree that gravity is preferred; 12ga wire, pumps, and PVC are cheap, and an interior excavation, fill, or placement operation with any type of materials at these volumes into a crawl space will be a real hassle, as could the center footer/wood bearing wall issue as that interior grade elevates. Keep in mind that concrete in water is a wick. Not an efficient one but not to be dismissed either. Concrete on gravel above the mean high water (with a vapor barrier) is fine for moisture mitigation, but what a ton of work that will be.

I think we may be over engineering this with not all the data in hand. The solution for this calls for measuring three times, cutting once. I bet we'd be all over top of one another with 2 or 3 similiar solutions, once Mike knows what is really going on there. He doesn't and neither do we, beyond the coming and going of water and what the pictures tell us. That's helpful but it's still exploration and discovery time, not solution time yet.

Could be a seasonal spring, could be a natural water table rise and fall, could be a perimeter drain or outfall placed too high or backgraded, could be the outflow pipe or perimeter pipe ran over a clump of soil and won't allow any or some portion of the field to drain, could be the downspouts tie in, and it could be none of that.

I'm reminding you Engineers to show you stuff, to go scientific. Your creed has effectively and correctly made that case with me on occasion.

 

[Investorguy]

Okay guys, a bit of new info.

While at a friend's kid's first birthday party, I talked to a local homebuilder about the issue. He's been building homes in this area for about 15 years as a GC and Framer. He said that the house he is building right now is in the wetlands and has a "rat pad" which is basically a concrete-covered crawl space, w/ the concrete placed just above the water table. I asked him if it would work where I live and he said it was pretty common up here and that it would be his choice for a permanent fix.

Well, I'll take that under advisement. It's just another opinion, but it's from someone who builds homes and knows the area. I asked how much 7 sack concrete was and he said $65/yard. He said the hose to pump would fit through a grate. So that's probably around $2500 or so in concrete, plus labor and any other costs, like truck costs or ?. Certainly not cheap, but minimally invasive/destructive (as opposed to a lot of digging and tearing up footing drains that are likely at least 8ft below the ground outside my house).

So I favor that option IF, and that's a big if, it's going to be 100% effective. Because like many have suggested, as expensive as it would be to do, it would be 10 times that to undo.

Okay, a lot of posts since I posted last, let me try to respond to some of them, starting back at the post after my last one.

@ Egon

I'm not sure how filling w/ concrete would require a redesign of the center wall (I'm assuming that's the same thing as what is being called a cripple wall). Code in the area is that wood has to be 8 inches from ground. Having concrete everywhere on the floor seems to me that it is the only "fill in" option that does not require changing the cripple wall.

As far as raising the house up, hopefully it won't come to that. And "For Sale" is not an option. I just went rural and can't imagine going back to suburbia. Plus there's just NOTHING out here in the same price range w/ acreage. And then wouldn't I have to fix it anyway prior to selling it if it was a big enough problem that I'd want to sell?

Uhg... I hope it doesn't come to that.

@inveresk

Hey man, I never asked... did you end up getting a plow? If you ever wanna come borrow mine for a month just let me know. It's not the kind of thing a guy like me will use all that much. Don't want to venture into the mud right now, but seeing as I got the 3pt bar turned around right, I think it'll work pretty well. I know it's a drive and a ferry ride, but just let me know.

My land has a gentle slope south toward the road/ditch. A tight pipe that just lay on the top of the ground that ran the 225 to the ditch would drain no problem, as long as it's not too sludgy. For example, water = no problem. Molasses = probably a problem. I hope that clarifies the is elevation issues.

As far as the concrete stuff, I'd have that professionally done. I think I want the 7 sack mix to ensure waterproofness. I know that I may have issues as the cold seams, but unless an engineer or the concrete guy tells me differently, I'd be inclined to go w/ the water proof stuff. A retarder would be good if it were me doing it, but I'm pretty sure I'd hire that out. It's not what I don't know that I'm worried about, it's what I don't know that I don't know that concerns me, if you catch my drift. Too important of a job to risk on a guy who got his tractor stuck in his own field.

As far as the water table issues go, I may have some new info here as well. I checked out the ditch along the road that the footing drain goes into. It has standing water in it. Probably a foot below where my drain pipe sticks out. I would not be able to tell you if that was the same level as my crawl space, but I would guess that it's lower. Seems it would have to be if my footing drains drained into it. OR, maybe that is just my downspouts and I don't even have footing drains, or maybe they drain into a rock well that simply overflows it's capacity in the rainy season. These are all questions for the builder. I'm in the process of trying to determine who that is. My work schedule's been hectic lately and the county planning department is in a really inconvenient location. Also, an engineer told me they pretty much chuck everything once a permit is granted, but they MAY have the name of the GC, if their was one. I know the first owner did some of the stuff himself; he may have GC'd the house himself. I'll learn this soon, hopefully.

Back to the water table height. I think I have a pretty good idea of how far the water goes up. When it dries, there is a VERY clear line on the footings where the water was. It's 3-4 inches from the wood in the cripple wall. Now, I haven't specifically checked it every day or anything like that, but it does seem that every time I've been down there it's been at about the same place. Given the mark it leaves and what I've experienced, I'm pretty convinced that the water level (1) is unaffected by rain, (2) stays constant and (3) basically lasts for a certain period of time according to how wet the surrounding land is. Given that, I think the likelihood of being able to pour concrete high enough to permanently cover the water table is high. I might go an extra inch or too, just for safety or a really wet year, although this year has been might wet. Several times I thought about building an arc.


@ EddieWalker

I like the whole "dig a hole idea and see if water comes up" idea. I don't have a backhoe though, so it'd be an 5 foot hole if I did it near the house... and the further away I get from the house, the less useful of an exercise it is. I'll have to consider that one further. That would help to further determine whether it is a drainage issue or a water table issue.

Believe me, I'm not going to pour concrete until I've determined that it will be 100% effective and the only permanent solution.

I've thought about the downspouts idea. But is that necessary if the top of the underground lake I have never varies throughout the rainy season? I was just down there and it's actually been pretty dry for the most part. It's right up there, as high as it ever gets.

To answer your question, I think that it would make sense that the water table would be higher at some times than it is at other times. As I mentioned earlier, the drainage ditch 200 feet away is not flowing, but it has standing water. Very stagnant standing water.


@ CurlyDave

I think we've cover most of your stuff in what I've said previously. I will try to talk to a RE lawyer next week, and I would definitely use pros to do the concrete work.


@bugstruck

Definitely not drunk on ideas. There is wisdom in many counselors and there is clearly a lot of experience on this forum. Also, if anyone else ever has issues like this, this thread will be there for someone to glean over all our banter.

Now, to your list. A lot of this will be evident when I talk to builder. I'm only going to dig stuff up if I have to, not at part of a search and probably destroy mission. I really hope I don't have to dig all that stuff up.

The 225 is right. I've measured it myself. Well, I measured the driveway, so it could be 235 feet. But it's somewhere in that range.

As far as the water table, it could be that the water table is right there at the level of the land. While you can't see any water, you can hear it running when standing there. Also, it's like walking on a sponge. You sink in a good couple inches wherever you walk out in the field, both above and below the house (in terms of grade, north being above). If it matters, the clay soil we have out here is notorious for holding water. I did plow and till one section of the field and it seems to drying out much faster. I can walk on it now without leaving footprints. 20 year old sod on the rest of the property.


@ inveresk #2

I think we've covered most of what you have here. Concrete is preferred b/c it'd be easier. Unless i hired a bunch of college students to act as a bucket brigade and pass buckets of pea gravel into my crawl space, the only access to which is inside the house, underneath the stairs. A local college ministry does "work days" to raise money for a summer mission trip, so this idea may be more feasible than it sounds.


@ Parttimer

I got a referal to Civil engineer who specializes in stormwater here. Hope to talk to her soon.

If I do the concrete route, I do plan to do it right. I'm sure the concrete guys will have a recommendation, which I would then run by you guys to make sure I'm not getting ripped off.

@ bugstruck#2

Concrete is parked for a month at least. I'm not going to poor it while there's still water in there. I don't think that would be a good idea.

I'm willing to try drainage, but I'm concerned that trying to drain the water table will be futile, no matter what I do. Hopefully the engineers will have some thoughts. I will post 'em up for sure.



Everyone, keep the thoughts coming if you have new ones or even want to rehash old ones. And discussions we have year will be of benefit to future "havers of this problem" as well as yours truly.

I'll keep everyone up to date on my progress as I try to do the following:

1) figure out who builder is and ask him about footing drains, downspouts, why so deep, etc.

2) find a RE lawyer, ask about builder defects and potential remedy

3) talk to civil/stormwater engineer


Again, thanks for all the hard work and enthusiasm in sharing your ideas. I have neighbors, and I have e-neighbors.

 

[Egon]

Investorguy:

Thank you for including my name in your summation as I really did not add to any solution.

Surely sounds like you have a plan in place.

You could use a post hole auger [ manual type ] to dig a hole and check for water level. Could even set up a grid of holes for monitoring.

Egon /forums/images/graemlins/grin.gif

 

[Paddy]

InvesterGuy,

Another few items to add to your "to do list"

1 get a firm quote on the slab concept...in writting. Insure the quality of finish and slope are layed out in the offer.

2 contact your county to inspect the drainage ditch at the road, standing stagnant water means it's not working either. Ditches need to be maintained. In our area, the county digs them out every few years. Take this a step further by walking the ditch a ways to see if a certain area has a problem.

3 At your access trap door from above, measure the depth from finished floor to crawl dirt. from your photo, this will be about the top of your footer. Now take this measurement out side at your wall and determine just how deep your footer is. have the contractor quoting the concrete, shoot a transit line from the house to the ditch. If you are below the dittch...concrete maybe your only soln.



4 when the situation drys out, use a post hole digger up against the foudation and dig a 2'x2' hole for inspection. You want to do this to determine if your drain is at the proper depth and that it's not full of mud. Also, you will see if enough and type of drainage gravel was used.

5 Review your entire lot for drainage. By the last post regarding "stuck in the mud", you have drainage issues way beyond your house. You should have drainage swales in/around the field. Also note, it's more likely you are facing max soil saturation not water table elevation. If the water table was that high, that ditch would'nt be stagnent, you'd have a fast flowing spring creek. Good or bad, many 1000's of swamps have been drained for ag use by a grid of drainage. It brings to mind to old joke, "you want to invest in some (swamp) land in Florda?". Turned out many made out real good after the Army Corp of Engineers drained them.

You will solve this, you have time to think it about it.

Patrick

 

[MarkV]

I’m new to this discussion and it has been very interesting. Investorguy, I am sorry you are having problems and wish I had answers rather than more questions.

I’m surprised there are so many suggestion of go after the builder. Here the builder has a warranty responsibility on a new house for one year to the original buyer. After that, assuming it passed and was inspected by local code enforcement you are on your own. Could be different in your area. I also don’t see the builder coming back several years later and saying ‘Oh ya, we knew that was wrong and will be right out to fix it’.

Not so sure about the legal route either. Sounds like the water issue was disclosed before the house was bought and an independent inspector also noted it in his report. Who are you going to go after with legal action? Even if this is a course that could be followed it doesn’t sound cut and dry so it could cost as much as the repair.

This does sound like a water table issue to me. Had something similar yet less dramatic in a house I had. During the wettest times you could see the water rising through cracks in the concrete basement floor. Our occasional problem was handled by a sump pump.

This I ask as more of a question than a suggestion. When I lived in the mid west it was common for farmers to run drain tile in entire fields to keep the water table low enough for farming. With all the talk of soggy ground all around the house is it feasible to set drain tile to bring the water level down in the whole area near the house? I know it is dependent on enough elevation drop on the property to have a place to drain to. I’m just wondering if that were possible if the end result would not correct the crawl space problem as well as dry up the immediate soil issues around the house. A sump pump could be installed inexpensively as a back up.

MarkV