First, thanks for all the amazing info on the site. I've laid slabs, block paving and built a new soakaway following the guidance given here and it has been invaluable.
I wonder if anyone can give me some help to resolve a boundary wall issue. My neighbour has raised the ground level and built a new extension to his house. This has left the ground level around 2ft above the DPC on one of my brick built outbuidings on his side, resulting in one very wet wall.
I've spoken to him and proposed we excavate to bring the ground level back down to the original level adjacent to my wall, and build a new retaining wall on his side.
Any tips on the best way to design this, and what if any drainage should be incorporated?
Thanks for the responses thus far, much appreciated. So far the neighbour has been amicable and I'll do everything I can to keep it that way. I'm in a somewhat difficult position in that I only bought our property earlier this year and the extension was built 7 years ago; the neighbour claims the ground level hasn't been raised significantly although I doubt this. I'm prepared to foot some of the costs in order to keep him on side and avoid legal expenses.
If a structural engineer is what's needed then I guess I'll have to contract someone. Any recommendations for suitable contractors in the Leicester area?
I'd be interested to know why the basic drawing I posted is unworkable, if you have time to expand.
When the ground has the weight of a structure bearing down the force pushes the ground outwards ( bulbs of pressure ) So you can't plonk a wall on subsoil. You need a foundation slab and possibly reinforcing to hold it all in. That's why you have ring beams around structures so the forces are contained, the weight pushes down, out, hits the beam and pushes up not down. In your case you would have plastic failure and the retaining wall being free standing would blow. A lot more to it than that but only way i can explain in it without going into stresses, strains, moments etc: i know it's only 2ft but 2ft soaking wet is a lot of weight. I'd probably opt for the tanking personally and filter drain.
Thanks Sean and LLL, that explains it clearly. Structural Engineer it will have to be then.
Sean I have read about a solution that I think is similar to what you are suggesting - basically dig out alongside my outbuilding wall, fix a damp proof membrane along the wall finishing below my DPC and then back fill with pea gravel. Is that the sort of thing you are talking about?
I imagine that is probably the cheapest solution, although given what you have said I'd be a little worried that eventually my outbuilding wall might fail.
We don't know the width or if it is gsrden, path, or wasteland. Maybe it could be battered down from the new build to below your damp course. The weight on the wall is why we are suggesting S E. The boss's work arounds on the main index could aldo be a solution. Our suggestions are just that 'suggestions', the choice is your's which way you go. Also photo's are a good idea for us to see.
Even if you put a filter drain I'd still check that the wall is capable of sustaining the weight and movement of wet ground
Any issue like this should have been picked up on the survey when you bought the house
Structural engineer is the safest option but dependant on size of buildings, depths of footings could be an expensive job
The gap between the two buildings is currently unused, but the neighbour plans to put a gate on the end so he can use it as path. The width is approx 1.5m. His extension is single storey with a pitched roof; my building is a single storey outbuilding with single pitch roof. This photo shows the gap; the white rendered wall is my outbuilding on the left:
I've just done a quick measurement of the relative heights. It's more like 40cm higher on his side rather than the 2ft I originally estimated.
BTW: Shaun, when you mentioned "The boss's work arounds on the main index could also be a solution." could you give me a bit more of a pointer as to the pages / info you mean?
