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Old 10-05-2011, 09:52 PM
 
Location: Carmichael, CA
1,933 posts, read 2,726,978 times
Reputation: 2922

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I have a 1955 house, built on a concrete slab. There's a very slight incline from the back fence towards the back of the house, so rainwater runs towards the house.

When I first moved in it had brand new carpets, and the first rain I had about a half inch of water in the back two bedrooms.

A few years ago, the guy who was mowing my lawn at the time and his brother put in french drains. They were put in too far back--about 8 feet from the back of the house--but they've stopped about 90% of the water coming in, and some winters no water comes in at all.

We seem to be getting heavier rain storms lately, so I'm looking at putting in drains right next to the house. The guy who mows my lawn now will do the digging, but he wants to use a pool plastic, very thick, against the back of the house, and backfill with sand and gravel. He says the piece of pool plastic costs $450.

Has anyone had any experience with this type of drainage work?
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Old 10-05-2011, 10:12 PM
 
48,519 posts, read 80,998,062 times
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Personally I see about getting that backyard regraded properly. Then have the foundation checked by a good foundation company as it may have sunk from that kind of constant rain runoff near foundation over the years.
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Old 10-06-2011, 12:25 AM
 
Location: Holly Springs
3,861 posts, read 9,271,586 times
Reputation: 2995
Ok, first of all I would advise against having someone that mows your lawn correcting your foundation water intrusion. Properly dealing with intrusion takes a certain level of expertise. Since you have had standing water in the rear bedrooms, that would suggest the water level may be higher than the slab during heavy runoff, rendering any physical barrier adjacent to the slab useless. You also may have damage to the wood structural members inside the wall cavity due to the rising water levels.
My recommendation would be to install a french drain system approximately 1-2' off the house which will carry water well away from the structure. Make sure your gutters, if present, are clean and the downspouts extended away as well. If you do not have gutters, install them first. You may also want to remove lower sections of sheetrock to determine if moisture has deteriorated the studs/sill or allowed mold to form. If you would like to ask any questions, feel free to message me. I am a building inspector and also own a moisture mitigation company.
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Old 10-06-2011, 03:35 PM
 
Location: Johns Creek, GA
11,876 posts, read 45,659,960 times
Reputation: 12996
Quote:
Originally Posted by cb73 View Post
Has anyone had any experience with this type of drainage work?

BLAM!- Fell out of my chair laughing.
Don't throw good money after bad. When it comes to home ownership- people almost always fall for the cheapest, most gimmicky B.S. I've ever seen or heard!
You obviously have a severe grading issue. House foundations should have a final grade of 6/10. That's 6" of fall- for 10' of run (there are exceptions to the degree of grade but, it has to be positive away from the house and not so severe that it causes an erosion problem).
When it comes to the housing industry I always keep this in mind-
"If it is of a mechanical means, it will fail!"
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Old 10-06-2011, 03:43 PM
 
Location: Texas
5,586 posts, read 11,831,318 times
Reputation: 10545
Quote:
Don't throw good money after bad. When it comes to home ownership- people almost always fall for the cheapest, most gimmicky B.S. I've ever seen or heard!
You obviously have a severe grading issue. House foundations should have a final grade of 6/10. That's 6" of fall- for 10' of run (there are exceptions to the degree of grade but, it has to be positive away from the house and not so severe that it causes an erosion problem).
When it comes to the housing industry I always keep this in mind-
"If it is of a mechanical means, it will fail!"
Thought maybe the OP needed to read this again. This is the correct answer. Anything else is a dog and pony show designed to milk you out of your hard earned money.
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Old 10-07-2011, 02:27 PM
 
Location: Carmichael, CA
1,933 posts, read 2,726,978 times
Reputation: 2922
I thank you all for your answers. In the past, an inspector and 2 contractors have looked at it. The inspector thought that someone had accidentally poured water in the bedroom and forgotten to tell me, and seemed to have no concept of water coming in from outside.

Both contractors recommended french drains, and both recommended sealing off the foundation, like my original post described. Neither recommended re-grading. I didn't mention--as I wasn't aware that it was important--my house sits on the slope of a very small hill. It sounds like re-grading would pretty much involve digging up the entire backyard, and I have 20 years of landscaping and producing fruit trees there already.

Although both contractors said they could do the french drains, both--and most contractors in this area--subcontract out the labor portions of the jobs to the illegal day laborers that sit on the sidewalk at Home Depot every day. The guy that does my lawn was laid off from a regular landscaping company who switched to cheaper day labor, and I'd honestly rather give him the work.

The lawn guy also said that he would re-grade the area from the house to the original french drains, which is about 8 feet from the house.

I did research the plastic, 10mil or 12mil and it seems most of the problem is it only comes in 100 foot rolls and I only need about 20 feet, so that seems like a lot of wasted expense.

I'm wondering if I just do the french drains next to the house and re-grade that first 8 feet, if that will be enough.
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Old 10-07-2011, 07:08 PM
 
25,800 posts, read 49,685,561 times
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Any system you come up with to keep the slab higher than the adjacent ground will help...

I've done similar with curtain drains, two rows, that direct water away and around the slab...

It is important, in my opinion, to have the top of the slab at least 6 to 8 inches about the ground to minimize water wicking up through the concrete.

Sounds like a completely fixable problem...

Not so sure about the pool liner... most here will excavate and lay in a good bed of drainage rock 18" deep with a sloped path in the direction you want the water to go...

Last edited by Ultrarunner; 09-04-2013 at 10:03 PM.. Reason: typo
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Old 08-27-2012, 12:32 PM
 
1 posts, read 37,659 times
Reputation: 13
I have a house at the jersey shore that is on a slab build about 1960. When we purchased the home, about 5 years ago, we found water coming in after a real bad rain storm. The next day, I dug a drench on that side of the house to the lagoon. We never had water again. However, it's time to put a french drain in around the house. I appreciate all of your comments. Just one more comment. The land, which is flat, was at least 3" ABOVE the slab.
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Old 07-25-2016, 09:29 AM
 
2 posts, read 17,400 times
Reputation: 10
All your suggestions here are very useful. Thank you!

I have a similar problem. My house is on bottom of a hill. It's built on slab foundation and on heavy rain, floor of one of the bedrooms closet getting wet. I am middle of digging drain outside of the house 8 ft away. How deep should I dig the drain to prevent water to get in? The bedroom floor is about 15 inch below the ground.

Grading is also seems to be negative in that area. How do I know whether I need to remove the soil or add the soil to fix the grading? Thanks again!
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Old 07-25-2016, 09:47 AM
 
2 posts, read 17,400 times
Reputation: 10
I read your reply on "Water intrusion in concrete slab house (foundation, Home Depot, pool, drains)" Very informative. Thank you.

I have a similar problem. My house is on bottom of a hill. It's built on slab foundation and on heavy rain, floor of one of the bedrooms closet getting wet. I am middle of digging drain outside of the house 8 ft away. I wish I had read your reply before. I could have done 1-2 ft away. Anyway, how deep should I dig the drain to prevent water to get in? The bedroom floor (slab) is about 15 inch below the ground. Does your suggestion only applies when the slab is above the ground?

Grading is also seems to be negative in that area. How do I know whether I need to remove the soil or add the soil to fix the grading? Thanks very much!
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