ok to have french drain right along the wall? 3

[fsh]

Hi,
I understand that it is a bad idea to dig a french drain right next to the wall. However I have a situation like this: in order to fix a leak about 18" below grade (top of the foundation wall), we digged a 24" trech along that wall, waterproofed the area, now it comes the time to back fill. I am planning on laying a PVC drain pipe and back fill with gravel to channel water away from that area. But after reading through this forum I am a bit concered of introducing water down to right where the weakest spot is. So is it better to back fill with original clay? I am thinking it would be ideal if I have a drainage system along that wall without puuling too much surface water down there.
Would really appreciate your inputs!

 

[oldestguy]

You will get a batch of ideas for what to do.

From me all I say is view a number of previous threads on the subject. I'll summarize and say if you use gravel backfill that is porous, but not a filter and it can plug with silt. Concrete fine aggregate, (concrete sand) will work better and won't plug.


Backfilling with clay would only be useful near the ground surface to keep surface water out of the porous backfill near your pipe.

 

[Ron]

Agree with oldestguy...

 

[fsh]

Hi oldestguy,
I checked out the 4" PVC drain pipe at the local HD store, the drain holes along each side is probably around 1/2" diameter.Will the sand get into the holes easily?

 

[oldestguy]

FSH

That's the pipe you might use for a septic tank disposal field, but not for sub-drain, unless it is wrapped with geo-fabric as a filter. I'd not use it.


The usual stuff I see available is "wrinkled" (corrugated) black plastic with slots maybe 1/16" wide. Its pretty flexible and withstands reasonable loadings of earth fill on it. You see this pipe, without slots, many times used as extensions on roof downspouts. 4" diameter is common.


If you have a Chance to ck out what slotted pipe to get, check for how flexible it is. If it sits in the sun for a, long time it gets brittle and easily breaks under loadings.

In the old days the common stuff was corrugated steel with 3/16" holes in the bottom quarter only. No longer available. Then, the upward flow into the pipe didn't bring along much sand.

 

[fsh]

I guess this is another example of how widely misconceptions can spread, if you google on "french drain" or "basement waterproofing" I would say about 90% of the websites advise against using the corrugated pipes, check out this website just as an example:

http://www.easydigging.com/Drainage/corrugated_pipe.html

So would corrugated pipes sold at Homedepot or Lowes be good enough? Some out there claim that those will collapes under the earth fill.

Just for my own education, why would you choose the corrugated pipes over the PVC slotted pipes? Do the reasonings listed on the website above make sense to you?
Thanks a lot!

 

[fsh]

Hi all,
I would also like your inputs on my plans of trench digging. I have no experience in this area whatsoever, hopefully I can do it right and avoid a lot of future headaches.Thank you in advance for your patience to finish my long post.
I need to channel water away from "A" area as shown in the attached picture. It is not cheap to hire a professional waterproofing company, plus all of them will "backfill with gravel". So I decided to DIY. As of now I narrow down to two plans. Plan 2 seems straight forward, but the challenge is that I need to cut open the concrete drive way and reseal it later, and I fear the trench is a bit too close to the house.
I am quite tempted to do plan 1 since mostly it will only involve earth digging, and here are my questions:
1. I will have to use T connectors and 90 degree elbows in several places, will this reduce the ability of the pipe to carry water away?
2. I will use perforated pipe in "A" area for sure. But starting from "B" area, is it better to use perforated pipe or solid pipe, if solid pipe, is it better to back fill with clay or sand?
3. If perforated pipe all the way, do I keep the sand around when pipe "daylights", or seal with sod?
4. Is there any material thatI can use to seal the house side of the trench in "A" area so that the chance of water entering the basement before gets carried away is minimized.
Which plan will you vote for? Any inputs are highly appreciated!