MarkM

I am told there is a mixture of everything from sand to gravel to clay and a fair amount of flint. But, luckily, no water. But, I do like the idea of sheet piles. I would worry, as you suggest, about the adjacent house. Maybe a combination of sheet piles on 3 sides and contig piles on the side running along side the neighbours. They only moved in a few months ago and have young children. They seemed very reasonable when I spoke to them. They did purchase the house after our planning permission was granted so cannot be too surprised. I just had a quick look and maybe there is an option to vibrate or push the sheet piles in rather than banging them in The quote for the contig piles plus capping beam is £47K. Which seems a big difference to what you were seeing for the sheet piles. I am supposedly having a sheet piler contact me and I will suggest this to him and see what he says. Thank you very much for the idea. It's certainly worth thinking about and investigating some more.

We have had a ground water check done and that doesn't seem to be an issue. They left us with an inspection point which I should check again. The £2500/sqm seems to be about in the middle of the quotes we have had so far. Perhaps my main worry is the lack of detail in some of the quotes.

Thanks for the welcome everyone. I've been investigating this build for about 3 years now while the planning permission and associated appeals went through and I can't believe I haven't stumbled across this site before. We've had a topological survey and ground investigation report carried out. The latter concluded that to batter the excavation would take 45 degree slope which would undermine the neighbours house and also take out some of our garden including trees. However, unless I got it wrong contiguous pile walls wouldn't be waterproof as they are 450mm diameter on a 600mm centre to centre pitch. The site is quite tight and there are telephone lines that are going to have to be avoided with the piling rig. As I see it I need to pile 10M down, add a capping beam, excavate and get rid of the muck. Then blinding and a slab plus waterproof concrete RC walls up to the ring beam. Then some form of membrane such as Delta My problem is the quotes I have this vary by £90K which makes or breaks the project for us. Strangely, the most detailed quotes in the lowest but, as they say, "if it sounds too good to be true..." The use case for this to be a house we can downsize into but we would like the basement to be usable as a living room plus bedroom with en-suite (Saniflow macerator). The project is both daunting and exciting. Mostly the former at the moment!

Hi all, Quick into. I have planning permission for a small house in Hertfordshire which includes a basement. The house is L shape above ground and squared off underground in the basement. The plan is for the superstructure to be SIPs I'm struggling with the basement and getting quotes and designs that are comparable. The only certain part is the requirement for a contiguous piled support structure. Anyway, I'm going to have a good read through the basement section of the forum and see what information I can glean. Regards Mark