# House on Slab - Water Problems



## Yodaman (Mar 9, 2015)

You definitely have a bad drainage situation there. All of the surrounding grade needs to be lower than the surface of slab by about 6 inches and then tapered away from the house. Short of that you need new drain tile installed around the perimeter. 

The flashing may help shed some water coming down the side of wall but will do little if you have water puddling over the slab. Managing the water runoff is where I would concentrate my efforts.


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## oh'mike (Sep 18, 2009)

That's just a bad design any way you look at it

YodaMan summed up the solutions---lower the grade---get that slab covered so it sheds water --or tapered to drain---

Find the original builder and slap him---he should not be hard to spot--his rain coat will be tucked into his pants.


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## gavroche (Aug 23, 2014)

haha.... yea, it was built back in the 70s... but i'm pretty sure it was raining just as much then as it is now. so not too well thought out.
I'm not sure when the prior owner put in the french drain, but it seems to help. we recently had a ton of downpour, and the water was draining ok. but a bit of water still soaks the slab.... mostly from wind blowing it to the wall. I'm thinking of extending the eaves another foot or two over the side when i redo the roof next spring.
1) i want to do as you suggested about lowering the grade. i was thinking of lowering it a bit, and putting small retaining wall about 3-4 feet from the slab (i can't go farther as there is a large Madrona (beast of a tree)... and putting a new french drain there. Retaining wall would help with leave buildup coming down the hillside perhaps.
2) should i get the 16-20" flashing, and bend it so i got 4-6" behind the siding, and then across the 10" of slab, and then bent over the side of slab....? Of course.... i'd need almost a 30' stretch... and i would have to hand bend it, so it would not be a perfect looking job.
3) so can i install that tiling you are talking about (got a link to what you are referring to?) over top of that flashing? or is it better do it a different way...?
4) i was looking at some of that hardiboard type siding that's a composit/concrete combination, in lieu of the wood siding. but from the reviews of it that i've read, if you don't install it just perfect (nail type, sealing the nail holes, etc...) that it could be worse off than just normal wood siding.

Thanks!


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## Yodaman (Mar 9, 2015)

quick primer on drain tile or french drains, google either and you can see many examples 
http://www.seepage.com/learning-center/what-is-drain-tile-101-how-drain-tile-works

Your french drains are the right idea just not done well. The whole system should have been much lower to allow water to settle rapidly below the slab surface in liue of washing up on the slab. The small pea stone on the surface is too small. And the surface of the stone is covered with leaves and dirt. Hinders the water seepage into the drain pipe and thus it washes up on your slab.
Here is a example of a very well done system. Maybe a little overkill for your project but it is your house!
https://en.wikipedia.org/wiki/French_drain#/media/File:FrenchDrain-02.jpg


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## Mingledtrash (Nov 27, 2015)

gavroche said:


> haha.... yea, it was built back in the 70s... but i'm pretty sure it was raining just as much then as it is now. so not too well thought out.
> I'm not sure when the prior owner put in the french drain, but it seems to help. we recently had a ton of downpour, and the water was draining ok. but a bit of water still soaks the slab.... mostly from wind blowing it to the wall. I'm thinking of extending the eaves another foot or two over the side when i redo the roof next spring.
> 1) i want to do as you suggested about lowering the grade. i was thinking of lowering it a bit, and putting small retaining wall about 3-4 feet from the slab (i can't go farther as there is a large Madrona (beast of a tree)... and putting a new french drain there. Retaining wall would help with leave buildup coming down the hillside perhaps.
> 2) should i get the 16-20" flashing, and bend it so i got 4-6" behind the siding, and then across the 10" of slab, and then bent over the side of slab....? Of course.... i'd need almost a 30' stretch... and i would have to hand bend it, so it would not be a perfect looking job.
> ...


Use a weep screed and/or weep screed deflector but as others have said you need to fix the grade first you should essentially have a drip edge at the bottom of your siding causing the water to drip away from the house instead of running down.


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## Mingledtrash (Nov 27, 2015)

your house is designed badly sorry here is a detail showing how your siding should be above grade.


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## ChuckF. (Aug 25, 2013)

To get something on the house that will not rot from water at the base of the wall, take off the bottom six inches or so of siding, put a Z-flashing under the siding edge, and put a 6" or so solid PVC board in place of the removed siding. A board in that application is called 'water table' trim. 

See http://www.hammerzone.com/archives/exterior/trim/water_table/pvc.htm for an example.

You can also put a piece of flashing at the very bottom, spilling onto the concrete. This fix takes care of the rotting bottom of the siding, it doesn't prevent water from seeping in between the crack between the concrete and the bottom of the the 2x framing. I'd caulk that with silicone before putting the flashing and water table on.

Make sure you have gutters wherever you can put them, with piping to carry that water away, and proper grading to keep water away from the house.


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## AllanJ (Nov 24, 2007)

Why would your 18 inch flashing (like this) not work? This is the same thing that roofers use where a first story roof (such as a garage) meets a second story house wall.

(For the roof they use an L shape instead of the Z shape shown.)


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## fortunerestore (Mar 6, 2014)

One thing is pretty clear; you have a bad drainage situation out there. As far as the flashing is considered, you can help shed water down the side of wall with it. And for the water runoff, put a piece of flashing at the very bottom. It will take care of the rotting bottom, preventing water from seeping in from those cracks between the bottom and concrete.


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