Help with gravel dept on french drain

[rickyb01]

Have a root cellar that sits 8' in the ground on three sides built into a hillside. I had it excavated and going to put a duel 4" French drain around the footer. How far up those walls would you gravel. The guy doing it wants to put gravel down up to a foot and then all the way up the wall going out about a foot with gravel and then dirt. I'm thinking at least 3' of gravel down and then all the way up with gravel going out a foot also. Either way will use plenty of soil cloth where dirt meets rock. Anybody with experience in doing this got any advice? Thanks Rick

 

[RedNeckRacin]

You need to explain things a little more clearly but I just did french drains for my house that has a walkout basement. I put cloth all the way around the clean crushed stone 2" minus. I had to keep the 4" drain 2 feet from the walls and then the invert of the pipe ended up being a foot down. I brought the clean stone up above the bottom of the wall and wrapped my fabric up and over top. My walls were already waterproof so I back filled with larger clean rock up to the surface.

 

[rickyb01]

Like you I have a root cellar that is built like a walkout basement. It's not connected to my home but the two side walls and back wall are built in the ground. I had it dug up to waterproof it and put dual French drains around it. It has a 21/2' wide trench dug around it and that trench is 8' deep. The guy that is installing French drain wants to put down 2" of crushed rock then put French drain in add another foot of rock and then backfill with crushed stone setting against concrete wall out about a foot as the trench is being back filled then using dirt to fill up the rest of the space. So at the bottom of trench he will have rock 1' deep and 21/2 wide. I think we need to go at least 3' of rock over the French drains. The rest I'm ok with. Also we will lay down a soil barrier and wrap crushed stone with it either way. Is 3' of rock overkill or good insurance because I only want to do this once.

Another question would you put up 3/4 Insulation foam board before you backfill. The waterproof company but up a waterproof fabric but there is no airspace between it and the wall. Trying to cover all my basses not cheap digging this thing up.

 

[RedNeckRacin]

If you have any path for the water to flow to get it away from the walls it will be a huge improvement. 1ftvs3ft won't be a huge change. Keeping the stone clean and providing a drainage path is the requirement. Insulation is definitely a plus but if its dry you are going to create an airspace and things should be warmer.

 

[EddieWalker]

The gravel is to allow water to flow freely to the pipe. You want it to be clean, which is why you use the fabric against the dirt. You want the gravel to go all the way from the pipe to the surface. You want the bottom of the trench to be free flowing with the holes on the pipe at the bottom so the water that gets to the bottom of the trench will flow freely through the pipe. One six inch pipe will carry more water then two four inch pipes.

 

[rickyb01]

I think one 4" will be fine and I'm putting the second one in for insurance. I don't think I have a huge volume of water getting to it. I'm also putting clean outs in the back for each drain. So you guys think 1' of gravel is ok or go 2' or 3' above the drains. Also there will be gravel up against the wall to the top going out a foot. I purchased a commercial grade fabric that I thought I would double layer on the bottom and sides and top of gravel to help keep it clean. Thanks for the comments. Rick

 

[PILOON]

You want the cellar walls tared or better still covered with a membrane so that they don't weep.
Then the drain pipe wants to be lower than floor level.
Crushed stone covered with geotextile is for sure the correct way to go.
Also the back fill should be sloped away from the structure so that surface water flows away and not towards the cellar.