French/gravel drain cross-section?

[Weetabix]

Hi,

Stone cottage with shallow footings- external levels need reducing and a gravel drain putting in (we live on free-draining limestone)
I keep finding conflicting advice online on how to install a gravel drain - some say gravel wrapped in breathable geo-tex against the wall, some say to dig the trench a little bit away from the wall?

Would someone be able to post a cross-section that they believe to be correct please? I'm going round in circles here!
Thanks

 

[TudorCottage]

I’ve just laid new French drains and I wrapped the pipes up like they were a Christmas present.

The old ones weren’t wrapped but the membrane had been laid as a sheet about 3 inches above the pipes so the pipes weren’t heavily silted.
The down side being as the membrane was laid across the entire width of the path, the whole path was heavily compacted with silt above the membrane which is probably why we used to get heavy pooling of water on the path in heavy rain.

We haven’t had any heavy rain yet so I don’t know how successful the drains are.

As for positioning, I guess it would depend on the fall of the land around your cottage and how high the water table is. If the ground slopes towards you I guess the closer to the building the better, if it’s flat I wouldn’t think it matters so much as the water will find its lowest point and drain away.

I picked the middle of our path (about a metre wide) as it’s flat and that’s we’re most of the water runs off the thatch.

I was a bit belt and braces and removed all the compacted soil and shingle down to the brick plinth of our cottage and replaced with new 20mm shingle all round, so even without the French drains I would like to think it will drain better.

 

[stuart45]

From the bottom of the foundation the angle of repose is around 45°, so you can't go into that area. Keeping a bit out from the wall means you can go a bit deeper.

 

[jsmac]

If you haven't already looked at www.pavingexpert.com it has comprehensive drawings and details on how to go about building drainage channels.