french drain to fix wet barn?

[gwynrew]

The back wall of the barn seeps water as it holds the neighbour's field back and the soil behind is higher than barn floor in front of the wall., maybe by 1-2 ft. The barn faces down the hill, so the back wall is across the slope.

The barn is too wet to use for livestock or hay, so we need to sort it. The neighbours are happy for us to pay to drain the bottom of their field. So what's the right way to do this?

We've been advised a french drain (trench + stone filling) behind the wall (basically level) and then down round the side of the barn and away down the hill into our field drains will take the water away and stop the seepage. Is this likely to work?

Is stone generally enough in a drain like this, or should we put a perforated twinwall inside the trench as well?

Is this going to carry the water away fast enough sideways to stop the seepage through the wall, or do we need
some sort of waterproof membrane behind the wall, along the low side of the trench, as well?

I don't know much about drains, but I'm starting to look into them...

 

[David.]

Will the neighbour wear you digging back the soil to foundation level round the back and sides of the barn? Then from this new level dig a French drain in about 6ft off the wall, complete with 20mm gravel and some perf twinwall in there?
That would be the final solution.

 

[Kiwi Pete]

French drains usually work very well if there is good fall.
Some take a while to seal the bottom with silt but the only thing that really annoy them are
1. Layer of leaves will seal the top
2. Tree roots

 

[Paddington]

Had similar problems with a barn built into the side of a steep hill flooding after heavy rain, digging down behind the barn revealed a clay drain with most of the sections either blocked, broken or missing and no gravel. I replaced these with a perforated pipe on and topped over with gravel. Flows like a good 'un now (touch wood).

 

[milkloss]

The best bet would be to remove the soil that is touching the wall and create a 45 degree bank with a gap at the bottom. Is suspect if you leave anything touching the wall, even with a French drain, it will still get damp.

We have a situation where we have dug a bank but the water still gets to touch the foundation and bottom of the wall so the water creeps up the wall and through. Maybe dig it back and use a compound that is used to seal basements on it? Then use a decoupler (bumpy plastic sheet) against the wall, drain at the bottom and backfill.

That would make it better and then if you want it bone dry you could drill from the inside and inject waterproofed into the base of the wall.

 

[MickMoor]

T

That would make it better and then if you want it bone dry you could drill from the inside and inject waterproofed into the base of the wall.

Fine in theory, but round here you would need tanker of waterproofing fluid. Stone walls are made of two skins of stone, with rubble filig the middle.

 

[milkloss]

Fine in theory, but round here you would need tanker of waterproofing fluid. Stone walls are made of two skins of stone, with rubble filig the middle.

Fair play, the. The best you’re going to get is to dig a bank out but is the barn going to become unstable even with a French drain?

 

[MickMoor]

The only pic I can find of the end of our house. As you can see, we know about houses built into the bankside. We have lived here since 1979. This was 2013, not this year's snow.

 

[phillipe]

If you dig out a drain tight to the barn ,pipe it with slotted pipe and put some tanking type membrane against the barn wall ,that will stop it

 

[Land Rover]

Your neighbor is going to have to be understanding .

Keep water where you can see it .

The best solution would be to dig out around the back of the barn and put a ditch in .
Whether you need to build a retaining wall , put a slope on it or whatever else , this solution is 1) guaranteed to work 2) is probably the cheapest option 3) Can be maintained and monitored .

Obviously the onward path of the water would need looked at , certainly with a silt trap prior to it entering a field drain .

 

[renewablejohn]

Have a look at using foamed glass as your french drain aggregate. Its very clever stuff as it does not wick moisture like ordinary aggregate and is also insulating. I am using it to stop damp rising and insulation for my underfloor heating.

 

[suffolksmallholder]

As @skinnyhoskins says is one way & the cheapest solution. BUT the best is the retaining wall. I did this to a cottage 20 years after doing the pipe & slate method. I built in a strong-point at the centre. A 1.2m radius semi-circle alcove in a 32' total run of wall so the CL was at the 16' mark. All the work was done in hollow blocks built over reo-bar bedded in the footing, filled with concrete, then faced up with bricks. The pipework was continued behind with weep holes just in case. No more damp inside the property.
I used a Newtonite product & french drain; https://www.newtonwaterproofing.co....MI-5jLjY7f2QIVp7ztCh0ZvwhREAAYASAAEgLhDvD_BwE further along in a small separate annexe that would not have been suitable for the retaining wall method. The soil is 2.0m deep at this point and 25 years on it is still warm & dry inside.
I'd be wary of a ditch as this will creep over time, that's all but it is another way but not as good really.
SS

 

[Clayfarmer]

I have similar problems. There are 3 main sources of water to worry about 1; soil moisture/percolation. 2; surface runoff. 3; roof water.

Ive come to the conclusion that the best solution is to place a gap between the wall down to below floor level, it doesn't need to be wide as long as it is maintainable and there needs to be a gulley/ slope at the bottom to direct the water away from the foundations. A land drain under this would help a lot as well. Alternatively a ditch with a bottom lower than the floor would work as said earlier.

 

[phillipe]

Problem is the op says its neighbours field ,

 

[Clayfarmer]

True but I was hoping that as the neighbours are happy for the op to pay for the draining their field then a ditch might be acceptable or a retaining wall with a gap of say 4". Ideally we need to know if the back wall is the boundary or a little in front of it.
Also, particularly as the soil is only 1 -2 feet high, was the barn built into the bank or has the soil slipped since then?? It might have a bearing on whether the neighbours are willing to let him scrape the soil away....
BUT I don't want to set the OP up for a boundary dispute as I don't think it would get him far when there are other cheaper quicker alternatives!

 

[phillipe]

True but I was hoping that as the neighbours are happy for the op to pay for the draining their field then a ditch might be acceptable or a retaining wall with a gap of say 4". Ideally we need to know if the back wall is the boundary or a little in front of it.
Also, particularly as the soil is only 1 -2 feet high, was the barn built into the bank or has the soil slipped since then?? It might have a bearing on whether the neighbours are willing to let him scrape the soil away....
BUT I don't want to set the OP up for a boundary dispute as I don't think it would get him far when there are other cheaper quicker alternatives!

I agree tota!ly ,but i use a rubber typ membrane that sicks to the wall,wall may need a littl rendering to fill gaps ,do it deeper than barn floor ,pipe it with access to rod somewhere and put soil back ,the boundaary could be the gutter or fascia line above as they stick ojt a little

 

[gwynrew]

Thanks for all the replies. Very useful. I don't think the neighbour wants to lose the grazing, so a ditch may be a bridge too far (if you see what I mean). The suggestions on membranes are useful. Someone I know offered some silage bags we could use instead (20+ years old...). There's no need to reply to that suggestion, unless you have a use for the bags yourself. We just need some sign that the ground might dry up a bit sometime this year.

 

[David.]

I suggest giving the neighbour a big bale of hay per year to replace all the lost grazing.