French Drain

[skier-hughes]

How big should these be?
Width from house?
Depth?
Does it depend on individual circumstances, or is there a standard that you generally work to.

I'm going to be digging out a trench for a new soil pipe, so thought I may as well get round to doing at least some of the french drain that the house needs, since some nice guy a few years back insisted that the house needed a concrete plinth round it!!!

I could google, but I'm off out, so thought I'd get a few meaningful answers and some utter crap from Penners by the morning

Graham

 

[Gervase]

Have a shufti here.

 

[Penners]

 

[chuckey]

Nuther good link :- http://en.wikipedia.org/wiki/French_drain
Frank

 

[DaveBrigg]

From Gervase's link "foundations of historic buildings do not always go very deep. Often, particularly with mediaeval buildings, the walls are founded only about 150 mm below the existing ground level"
From our experience, that's a rather generous estimate. :shock:

 

[skier-hughes]

Cheers Gervase, that was the link I remember seeing before but just couldn't find it with my quick googling and I just don't trust wiki.

 

[outlaw]

I normally go down as far as the footing, but not right up to it at the bottom of the trench, a "u" shaped trench 450mm wide lined with a geo-textile membrane linning it, with a perforated land drain in the invert, then back fill with shingle from 10mm-50mm mixed well, wrap the membrane over the top and top of with more shingle. You still need some sort of fall on the drain pipe, so start at the highest point and work your way along getting deeper, 1:20 will be more than enough of a fall.

Tony

 

[FamilyWiggs]

Wrong species I think Penners - far too big for otter crap.

 

[Ushy M]

I normally go down as far as the footing, but not right up to it at the bottom of the trench, a "u" shaped trench 450mm wide lined with a geo-textile membrane linning it, with a perforated land drain in the invert, then back fill with shingle from 10mm-50mm mixed well, wrap the membrane over the top and top of with more shingle. You still need some sort of fall on the drain pipe, so start at the highest point and work your way along getting deeper, 1:20 will be more than enough of a fall.

This is exactly the approach we adopted only using cobbles instead of shingle. In terms of distance from the house, we had to work VERY close as this was the gable end of the house which is in the churchyard and the nearest burial is only a few feet away! (Surveyor told us this wouldn't be possible and we'd have to put in a damp-proof corse - wouldn't have known any better without joining SPAB and this forum.)

 

[Penners]

far too big for otter crap.

:lol: :lol: (I'm ashamed to say that it took me a couple of minutes to get that one!)