a powe
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Joined: Fri Apr 01, 2016 1:31 am

Re-grading next to foundation - French Drain necessary?

The side of my house has a rock bed running alongside the entire length, about 60 feet. I absolutely must redo the grading alongside the foundation, as currently there is basically no slope.

However, due to the extreme closeness of my neighbor's house (only 10-12 feet away), combined with the fact that the shared turf in between our homes is basically at the same grade as the tops of our foundations, I cannot easily create any kind of slope.

Here's a drawing of the current situation, as well as the problems I just mentioned. It shows why I cannot simply create a slope and call it a day.

https://I.imgur.com/830jLZl.jpg

It seems like the only option is to go all-out and install a French Drain starting about 2 feet deep (and getting deeper as the pipe slopes downward), at around 3 feet away from the side of my house.

Is there a better and/or easier option? [To reiterate, the key limitations are: A) I need to re-grade the first ~3 ft. of soil next to my house to create a slope, and B) I can't change the height/level of the turf in between my neighbor's house and my own.]

If not, then please take a look at the following drawings, and critique my plan. I did a lot of research and spent a lot of time planning, but I truly value anyone's opinions, as I am a complete amateur in this.

Front view (overall view and close-up view): https://I.imgur.com/fDSKsh8.jpg

Side view: https://I.imgur.com/ZQ2h3ec.jpg

Some random points (reference the pictures for easier understanding):
  • I will be using perforated PVC pipe, not corrugated plastic tubing.
  • I don't plan on using any sort of glue to adhere the sections of PVC together; I don't think that will be a problem, will it?
  • For the time being, I will be using cheap black plastic edging along the rock bed. However, I believe that the way I've designed the layout will make it very easy to switch it out for stone edgers at a future date, as the edging will already be sitting on rocks, so I will just have to sweep some of the larger River Rock out of the way to reveal the Pea Gravel, and then set the stone edgers on top of that.
  • I will use varying sizes of gravel around the PVC pipes in order to create a natural "filter". I will do this instead of using a "pipe sock", as some people do......
  • ....But! I'll also be lining the trench itself with high-quality, extra-permeable, extra-durable landscape fabric. I debated whether or not to do this for a long time, but ultimately decided to, because A) it will be an additional layer of filter to keep soil from reaching the pipe, and B) the fabric I'm using is extremely permeable (according to the label), so it shouldn't impede water flow at all.
  • I am considering also covering the top of the trench with a layer of the landscape fabric, above the top layer of pea gravel, and under the decorative river rock, to help prevent debris from finding its way down into the trench. I am undecided on this, however.
  • I spent a lot of time debating whether to use solid plastic sheeting on the sloped section in place of the permeable landscape fabric. I currently am leaning toward the landscape fabric, as it is much healthier for the soil underneath, and also because the soil is very highly clay-based, meaning rain water should still run down the slope quite well and not be soaked directly into the soil. However, the plastic would obviously be absolutely best in terms of repelling water and sending it down into the trench, so I'm still struggling with this decision.
The rest of my plan should be very evident in the drawings. Please let me know about anything I screwed up on, or if there's a better way to do something. Thank you very much for your input!

imafan26
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Posts: 13999
Joined: Tue Jan 01, 2013 8:32 am
Location: Hawaii, zone 12a 587 ft elev.

How big is the French drain? Usually there is a sock that fits over the pipe to keep it from clogging. Why PVC? french drains are sold already perferated and they are actually more pliable especially if you have to go around corners?

Is your yard puddling? Why do you need to grade?

You can do surface drains with regrading, by creating a swale instead. You would put the swale more or less near where the two lawns meet and slope it toward the street. I would put rain gutters on the house and extended those out with pop up drains to keep rain water away from the foundation.

a powe
Newly Registered
Posts: 2
Joined: Fri Apr 01, 2016 1:31 am

My plan is 3 inch PVC. The trench would likely be about 7 inches wide, and 12 inches deep.

I chose PVC over the corrugated pipe because I'm not a fan of the actual corrugations, to be honest. I like the smooth interior of the PVC, so water can drain out completely. Also, since PVC is rigid, it's easier to create and maintain the slope I'll need. The PVC does also come pre-perforated as well, so that's not an issue.

I know the corrugated pipe has the sock, but the PVC doesn't. I guess I'm trying to re-create the missing sock with the landscape fabric lining the trench. I don't have corners, though, so no worries there.

I need to grade simply because the turf is totally horizontal right now, and I'm worried about that being harmful to my foundation long-term.

We do have rain gutters, but with a strong wind, rain still sometimes is pushed against the wall and down the foundation. And with no slope, there's not really any natural drainage.

The swale won't work because it'd create a swamp right in between the houses every time it rained. And you only have a few feet wide path to our backyards, so we'd be walking through muck. Plus, having a tiny quasi-riverbed running in between our homes isn't very aesthetically pleasing, and my neighbor is the picky type. He'd never go for it. Keep in mind, there's only 10-12 feet between our houses, and even less between our rock beds, so little things like that have a big impact.

Thanks for the reply!



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