Crawl space water control

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  #1  
Old 02-12-15, 04:33 PM
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Crawl space water control

My house is on an almost flat area and the crawlspace floor is about 1 foot lower than the surrounding. The crawlspace is unfinished - only about 3 feet high with dirt. When it rains the crawlspace gets wet: first around the foundation walls and gradually extends to the center. Eventually the entire crawlspace becomes muddy.

There is a sump pump at a corner, but water only gets to it after the entire crawlspace becomes muddy. Because the lot is flat, majority of the rain eventually ended in the crawlspace (in fact there is one entry next to the sump pump that let the outside water gets into the sump.)

I am looking for a solution to keep the crawlspace dry. I have read some from the internet. Here are the things that I do not think apply to me:
  1. There is no ground water (so I do not have to worry about it)
  2. I cannot prevent the water from getting into the crawlspace from outside
  3. outside-the-crawlspace solution is unlikely to work

Given this, what could be my solutions (we have rains only during the winter)? will a french drain help? If so, how deep it has to be?

Thanks,
John
 
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Old 02-12-15, 05:26 PM
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What is your goal? Do you want a dry crawlspace floor or to prevent moisture from making it's way up into the home?
 
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Old 02-12-15, 05:47 PM
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And why can the foundation not be waterproofed outside?
Why can the grade not be raised so it slopes away from the foundation?
Any gutters?
Any mulch or flower beds forming ponds against the foundation?
Waterproofing is done outside not under the house.
Pictures of the outside may help to understand your reasoning.
 
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Old 02-13-15, 09:21 AM
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Thanks for the quick responses.

The goal is mainly to prevent damage to the house. Although it rains only during the winter, the mud gets dried only around Aug/Sep. Literally the foundation is surrounded by mud from Dec-Sep.

I also read that the best way is to prevent water from getting into the basement. But here are my challenges:
1. There is clearly much more work to do it from outside.
2. One side of the house is concrete, the other side is a very low deck. At the back it has a raised bed with plants.
3. The basement is lower than outside by about 1 foot.
4. There is no way for me to divert the water away from the house unless I use a pump. When it rains, the entire backyard is literally under water (yes I have tried to lead the gutter water away).
5. The basement is just with dirt and is relatively easy to put in something.

I have no experience what so ever and that's why I am asking here for help. I will see if I can get some pictures posted later.

Sounded like doing it in the crawlspace is a waste of time and money, correct?
If it has to be done from outside, would it be a french drain around the foundation reaching the foot or something better?
 

Last edited by john111; 02-13-15 at 09:41 AM. Reason: reply to both posts
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Old 02-13-15, 09:52 AM
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First step is figuring out where you want all of this water to go. Do you have any drainage anywhere?
 
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Old 02-13-15, 10:17 AM
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The only option I can think of is to lead it to the sump (in the crawlspace). I can have another one outside, but not sure if it is legal.
 
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Old 02-13-15, 10:24 AM
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One option is to encapsulate the under side of the floor (ceiling of the crawlspace). Properly done it would prevent the moisture from the wet crawlspace from affecting the wood structure and insulation of the house. It's relatively easy & inexpensive but does not address the water in the crawlspace.

How much water do you get in the crawlspace? If you have enough water to direct it to a sump I would worry about erosion which gets back to addressing the core problem of how the water is getting in there in the first place. Which as you know generally means addressing the problem form the outside.
 
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Old 02-13-15, 10:30 AM
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How is the sump and pump going to help if it just dumps the water back outside into the flat yard?
 
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Old 02-13-15, 10:42 AM
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There are storm drains on the street. Just the lot is slightly lower than the street. Once the water is pumped on the street it will not coming back .

When there is a heavy rain, the water in the yard can easily be a few inches deep. It eventually gets into the crawlspace. I see some holes drilled through the foundation concrete to let outside water get in.
 
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Old 02-13-15, 10:47 AM
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I see some holes drilled through the foundation concrete to let outside water get in.
I would be thinking about digging those out on the outside to patch them.

I just don't see what you're going to do with the water - you can't pump it on to the street.
 
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Old 02-13-15, 12:22 PM
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Would the city allow you to tie a drainage line into their storm drain? Since they originally approved the construction of this home, they in effect created the problem. If your property had a proper slope, all of that water would be draining to the street anyway.

If you can't drain to the street, then the only other choice would be a very large and deep drain pit that could direct the water down through the soil. Our town just created an eco friendly example where surface drainage was directed into this absorption area as opposed to onto the drainage system. It included all of the appropriate plants and shrubs. How large depends upon the soils and would still probably need city approval. Given the choice between the two options they might prefer a connection to the storm drain. Need to ask.

You will always see a collection area associated with housing developments, so if you have enough property, that may be a direction for your thinking.

Bud
 
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Old 02-13-15, 12:25 PM
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pumping the water onto the street is pretty much what every home is doing.

I just need to find a way to collect the water into the sump before it soaks into the crawlspace mud. Seems so hard to do.
 
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Old 02-13-15, 12:43 PM
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I would put in a vapor barrier just like what every crawlspace should have. Make sure all seams are sealed. The water will be trapped under the plastic so it can't do damage to the wood.
 
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Old 02-13-15, 04:22 PM
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we wtrproof exterior walls all the time AND install exterior pumps to discharge the collected wtr,,, in most areas, its illegal to discharge into sanitary but storm's fine ( street ),,, tell me again why an exterior system will NOT work ? ? ? we do 'em & they work fine,,, you need to think ' manage the water ' NOT ' stop it '
 
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Old 02-17-15, 09:37 AM
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Thanks again for the responses. I am almost convinced (by your responses) that doing it outside is the proper way. I will think what I can do. Suggestions/how to/tips are always greatly appreciated.
 
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