Surface Water Drain & Pitch


  #1  
Old 04-12-05, 10:21 AM
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Surface Water Drain & Pitch

I currently have a brick patio in my backyard, which after I purchased my home I realized that the pitch of it is such that any rain water runs towards the back of my house (this of course wasn't caught at inspection time.) This has caused significant water damage to the sub-flooring of the house (the rear of the house is an addition built over dirt, no slab/basement/vapor barrier.) My home is a rowhome that is, according to my insurance company, located on a street with significant water issues, especially since my home is downhill from some other homes. In other words, I've got water coming at the side and back of my home.

Looking at the back of the house, the downspout comes down the left side and into PVC. Down the right side of my house is a concrete alley which belongs to my neighbors. Next to the my cinder block foundation in the alley is (was) a drain cap that came straight out of the ground

After doing some digging this past weekend, I discovered that the drownspout/PVC pipe runs along the back of my house, next to the foundation, around the right corner and ends at the cap. All rainwater that enters the PVC, stays there, as there is no way for it to drain. Hence the reason water has been leaking into/under the cinder block.

I ripped all of this out, and began to dig a trench about 8 inches off of the back/side of the foundation with the hope of installing a french drain system (which would also include the downspout) to capture any water running towards the foundation before it gets there. About 5 inches down around the entire house is red clay. I also coated the cinder block with DryLock in hopes of adding an additional layer of protection.

The problem I am facing, and need some guidance on, is how in which to allow the french drain (or whatever drain system) to drain away from the house, possibly down the alley. If looking at the back of the house, I start the higher pitch of the drain, running from left to right, with it ending around the right corner in the alley, currently the pitch of the drain would be such that it ends under the level in which the concrete for the alley begins, obviously not allowing the water to drain anywhere, but back into/under the house. Ideally I'd like the drain to drain down the alley and into the street, plus I don't want the drain pipe exposed as you walk out of the back door, but this might not be an option depending on the pitch needed.

One thought I had was to just run the drain along the back of the house, (not wrap it around into the alley) and basically into the ground. Of course, 1) it defies the purpose of a drain, 2) it drains into clay, which doesn't drain, and 3) it likely puts the water into my neighbors yard. From the side of the house to the alley (about 3 feet) I would pour a concrete slab in an effort to thwart water coming at it from the side.

Hopefully this makes sense. Thanks in advance for your time and assistance.
 
  #2  
Old 04-12-05, 01:29 PM
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The brick patio issue is one that can be resolved by the addition of a trench (or trough) drain adjacent to the house. They are common on commercial plaza decks, entrances to parking garages, etc. Smaller trench drains are used in the surfaces surrounding a swimming pool or similar applications.

And from the sound of it the downspout should be relocated (if possible) to the alley-way side of the house.

If all of these elevations are too low to drain above grade... look into a small sump/pump unit. A small basin or sump is set into the ground to receive the run-off from the trench drain and downspouts. There is a pump with a float valve in the sump that is activated when the water rises to a certain level and the water will be pumped to wherever you wish to run the pipe.

One idea to look into anyway....

Good Luck!
 
 

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