Land drain distance from house wall

[somerset]

Many thanks for all the info on this site ... I have a situation similar to others, where ground on two sides of my house has a gentle slope towards it. I have serious water ingress at cellar/floor joints, (3ft of water max depth!) and have alleviated with a sump and pump (original cellar drain was destroyed by nearby new house construction). Cellar floor is bricks laid in lime mortar on clay. Cellar floor is waterlogged. However I still have streams of water flowing across the cellar floor when it rains, while the water is pumped out by the sump pump.

I plan to install a perimiter drain inside the cellar, at foundation but want to reduce the amount of water getting there in the first place. My garden is the lowest point, and neighbours gardens all drain into mine, and then into the cellar. The ground is very waterlogged after rain.

I plan to install a French drain in the garden, and drain into a surface water drain (not soak-away)
The house is cellar + 3 storeys, so tall, pre-1870, stone construction on clay soil with clay shale underneath.
I planned to install a French drain to about half of cellar depth, so approx 3-4 feet.

Whilst I realise every case is different, and there are no guarantees, roughly how far out from the foundation would you choose to install a French drain in such a case?

In diagram from your archives you show 1m from foundation, but with an older property on clay soil I imagine I should be cautious?

Many thanks

[Tony McC]

I don't like so-called "French Drains" which is a huge part of why I write so little about them on this site. They are centuries-old technology and while they can work in some cases, there are usually better ways to achieve the desired outcome using modern methods and materials.

I suspect that what you need is an interceptor drain which could, effectively, be built directly against the cellar walls but I'd be sorely tempted to use a waffle board/drainage composite to protect the masonry from water ingress. The key point would be not to have the base of the drain any lower than the bottom course of masonry.

[local patios and driveway]

I think you know that it needs doing properly but maybe you are not in a position financially. I dont see that there is any diy fix that will be effective (not even close) it needs excavating and as the boss has said a barrier system put in place around the perimeter of the building and then have the interior room tanked.

[somerset]

Hi Tony,
Thanks for the advice, and yes an interceptor drain is what I was thinking of (I did read about it before but then described a French drain in the post). I do not have the nerve to deeply excavate on the outside of the cellar walls - its a very tall stone building. As so much of the water is coming from behind and to the side of the house (higher land) I intend to try an interceptor drain spaced 1m+ out from the walls. At very least it should reduce the amount of water heading for the cellar!

[somerset]

I think you know that it needs doing properly but maybe you are not in a position financially. I dont see that there is any diy fix that will be effective (not even close) it needs excavating and as the boss has said a barrier system put in place around the perimeter of the building and then have the interior room tanked.

Thanks - yes - its more that it is not financially sensible for me to do this. I would not get the investment back I'm sure. I am however keen do do what I can to reduce the impact of water on the structure of the building itself. I do plan to excavate (to 1.2 to 1.4m as an interceptor, with a 3 tonne digger, but my DIY nerve does not extend to exposing the cellar wall on the outside, so it will have to be spaced out from the wall if we do it. The cellar walls are not actually that wet, but the water enters at cellar floor level at 3+ points. I'm not intending to use the cellar as living accommodation, but do want to get the moisture levels down. It is ventilated by three high level open vents (openings with metal bars).

[local patios and driveway]

I would say you cant afford to NOT do the work. Repairs cant be looked upon as an investment but rather a neccesity.

[dbostrom]

If it's any help I had a similar problem (on one side of our house only) and learned of interceptor drains from this site. Because of access constraints preventing us from approaching closer to the structure we installed an interceptor parallel to the house but spaced about 7' out. Problem solved; water traveling from our neighbors simply can't cross the interceptor. We went with the "turtles all the way to the bottom" interceptor approach, ending up with something I suppose could be called a "fin drain" or the like. The whole thing topped with a nice gravel path, a bonus feature which also serves to capture (seemingly magically disappearing) water traveling across the surface during deluges

Cost was a few hundred US dollars for gravel, pipe, geocloth and trenching machine rental. Construction required a couple of days and about a dozen Ibuprofen tablets.

If the water you're talking about is really traveling from neighboring properties then you don't really need to have the drain sitting against the wall of the house, or at least that was our experience. Not sure what the pros here think about that but I'm sure they'll pipe up!

[lutonlagerlout]

welcome to the brew cabin Dbostrom
it would be nice to hear some non European views on issues that arise
LLL :;):

[dbostrom]

In general you folks seem way ahead of us on rising issues in the form of damp and water. Just try finding crates for soakaways here, as a homeowner. For my project I ended up using loosely stacked breezeblock, wrapped in geocloth and topped w/4" concrete slabs. Works well but was of course more awkward to install.

[Tony McC]

The three most popular topics raised by North American readers: Where can I get.....???

1 - Resin bonded/bound aggregates

2 - Recess tray covers

3 - Storm crates

...in some ways, the US can be so far ahead of Europe it's scary, but then with others, it as though the trade there is existing in the 1930s. I keep thinking to myself: am I missing a trick here? Should I fill a container with resin, trays and storm crates and head off west to seek my fortune?

I have mentione dthis to colleagues and friends in the US, but they just don't get it!

[dbostrom]

Well, as far as SUDS goes we seem behind the curve; as a group we're having a hard time making a connection in our minds between water rapidly exiting our own property and other people's basements filling with water.

In our particular case whatever water leaves our property goes into a creek at the bottom of our garden, that creek passing numerous similarly situated homes downstream. With the creek watershed (about 1/4 of Seattle) being ~33% paved w/street runoff ending up in the creek you can imagine what happens when it rains. It's incumbent on us to both (a) keep water out of our own basement and (b) somehow reduce the flow rate of water off the property so as to be helpful to other people along the creek. Hence our "hybrid" drainage wherein we try to soak up as much water as we can, w/soakaways relieved to the creek when the water table and/or percolation rate can't keep up.

Then we hope and pretend enough people do this to make a difference... :p Oddly enough for us the creek is not the problem; it's groundwater/surface runoff from adjacent property that keeps our barge afloat during the winter.

Funny thing about storm crates is how similar they are to milk crates; just a minor bit of retooling and the same factory molding milk crates could churn out storm crates. A little polyethylene and a lot of air.