Patio over soakaway - Present patio has sunk

[flummoxed]

I did try to e-mail info@pavingexpert.com on 13 Sep with my query but because I am not very computer literate I am not convinced it went as I have not had a reply. If it did, please accept my apologies for also posting my query on the forum. I have scoured your brilliant website but cannot find a specific answer to my problem, which is this. My present patio is 20 years old and consists of Marshalls Saxon 3 x 2 paving. I want to renew it and am looking at Indian Stone, primarily because the price now seems so competitive compared with concrete products. However, the existing patio has sunk very badly in one place, and I think I know why because I was around when the house was being bult. The soil is very, very sandy so the builders decided to drain the surface water via soakaways. These were simply largish pits filled with stone and with a pipe from the various grids around the house. There was one pit measuring 6'0" x 4'6" situated partly under the patio, where it has now sunk very badly. The lawn has also sunk badly where it was over another pit; I pulled the turf back some years ago and made up the ground and put the turf back but it has now sunk again. This leads me to think that the ground will continue to sink over time as there is water continually flowing under it and it would seem to me that some kind of reinforcement or bridging structure needs to be in place under the patio to prevent future sinkage - or will some kind of membrane do? Any suggestions you have would be greatly appreciated as I do not really want to reposition the patio. Also, on your website you imply that some of the indian stone is of doubtful quality. How do you assess the quality? I have been looking at stone retailing at around £15 per sq.m. plus Vat, including delivery, with a thickness between 20 - 40mm, averaging 35mm. The price is O.K. and it looks O.K. to me, but how can you tell? Are you also able to suggest a contractor in the Mid Cheshire area who I could rely on to address the solution (if there is one!) to my sinking problem. Many thanks.

[dig dug dan]

Hi

if the soakaway has been constructed correctly, then any further settlement should be minimal. If the existing patio was laid over the soakaway not long after it was dug, then settlement was inevitable.
I would find where it is when you construct the new patio, and cast a concrete slab over the top to bridge it. This should prevent the patio sinking later on.
There has been talk about indian stone recently with some contractors saying that there are some unusual sizes.
I have just laid a large quantity of these "unusual" sizes, and I was sceptical at first, but when completed it looked great, and i found no problems with it. I will be laying 47m tomorrow, and again, no problems. Just be sure to choose your colours carefully, and providing your crates are sealed, they will be fine. If they are full crates that have been opened, you could be buying other peoples cast offs!

[Dave_L]

I will be laying 47m tomorrow, and again, no problems

I hope the weather holds off for you like it did for us today - now it's raining cats and dogs! As far as I'm concerned it can rain as much as it likes overnight!

[dig dug dan]

I agree!!
trouble is, I have to get this finished and pointed as i is a surprise for my father in law when he comes back from hols on saturday. Big party, everyone coming to look etc.etc.!
I can lay slabs in the raind, but i can't point!!

[Dave_L]

I'm sure we'll pay dear for this decent weather we've had of late, during the forthcoming winter.............brrrrrrrrr

[flummoxed]

Many thanks, Dig Dug Dan, for your help.