06:39AM | 03/25/04
Member Since: 03/24/04
2 lifetime posts
My house is 16 years old with a block foundation and the exterior grading is good; 6" in 10'-0 drop. During particularly hard rains water enters my basement through some hairline cracks in the slab (the builder never installed expansion joints). There a few places along the wall/floor joint where this happens too. I suspect that there are no french drains or that they are clogged. As I cannot find where they discharge I suspect the former.

As we are planning some major landscaping anyway, I have reconciled myself to excavating and installing drains. I can't seem to find any recommendations for the amount of gravel backfill to install though. I was planning on using 1.5" (3b) gravel, but how far from the foundation wall and how high should it extend? I'm also wondering if landscape fabric is suitable as a filter around the pipe? If the entire trench can be filled, can I line the trench wall with it as well prior to backfilling? Thanks for any help you can provide.


02:05PM | 03/28/04
Member Since: 11/06/02
1280 lifetime posts
There is a drain sock made for slipping right over the perforated pipe or I think you canbuy the pipe with it on in some places.

I use up to 1.5" stone surronding pipe about 12-18" and fabric around that too.

There are also products like Battledrain that can be applied to the wall itself to lead water to the pipe by creating a drainage mat/plane

Excellence is its own reward!


03:48PM | 03/28/04
Member Since: 03/05/04
301 lifetime posts
...water that comes up through basement floor and/or up through the isolation joint and NOT because you have cracks on the outside of your basement walls..only then you may want to install an inside drain tile method and maybe a sump pump as other choice.If installed correctly it should control the water level under the floor & keep water off your basement floor.Be VERY careful who you hire!


06:43PM | 03/28/04
Member Since: 01/28/03
693 lifetime posts
When installing exterior drains and drain tiles, the rigid drains need to be placed in at least 12" of 3/4" crushed stone, then covered with at least 3-4 feet of additonal crushed stone.

Trench walls need to be lined between the dirt and stone with a filter fabric, tar paper, or plastic sheeting to keep silt away from and blocking the drain pipes.

The 3-4' of stone once placed also needs to be covered by a filter fabric, tar paper, or plastic sheeting to keep silt from percolating down into the drain tiles. Only then should the trench be backfilled with soil and sloped away from the structure.

Drain tiles should NEVER themselves be wrapped with any kind of 'sock' or filter fabric since this only leads to premature blockage and failure.


03:19AM | 03/29/04
Member Since: 03/24/04
2 lifetime posts
I've started to come around to the idea of installing the underfloor drains. In my case, with the water coming from under the slab, they make sense. If it were my block walls that were leaking I would never install them; I'd rather catch the water before it entered with exterior drains. Treat the cause; not the symptom.

Does anyone have experience with interior drains that have runs not just along the walls, but out toward the middle of the slab as well? I have hairline cracks all over the slab and while the lions share of water comes in by the walls, a good deal still comes up towards the middle too.

While I'm OK with installing a sump, I have the ability to easily make do with a gravity system too. Any thoughts on that?

plumber Tom

10:14AM | 03/29/04
Member Since: 05/10/03
801 lifetime posts
All you have to do is install 2 tee's on the pipe that runs on the inside. This is called a lateral. It should be connected at both walls to pick up the water from the middle of the slab. Gravity is fine, just slope the pipe 1/4" per foot, maybe deeper near the crock depending on the level of your footer.


10:51AM | 03/29/04
I want to thank everyone for responding to my questions. You've helped get me oriented on this.

Alright, I'm just about sold on the interior drains. I've personally seen one job where the installer alternated removing 4ft of the slab and leaving the next 2ft undisturbed. That was to prevent the bottom of the wall from buckling inward. It required a lot of tedious hand digging under those 2ft. Has anyone else heard of such an installation?


08:50PM | 03/31/04
Member Since: 01/28/03
693 lifetime posts
Yup. As Plumber Tom said.

Best basement de-watering systems have peripheral drains as well as cross laterals every 10 feet or so.
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