The Brew Cabin

I have recently received a quotation from a contractor to relay my existing patio, which is 17m x 3.5m in dimension and retained by a 225mm solid brick wall. The current patio has concret slabs laid on a bed of sand and has settled in many areas.

The contractor has allowed for removing the existing sand and an amount of subgrade to allow for the correct level to be made then to lay a minimum 100mm reinforced concrete sub base and finally bed the new stone slabs on a layer of mortar and point.

Can anyone advise if this is the most appropriate and costs effective method of preparing the sub base ready for laying the new stone slabs or are there any other preferred methods of construction that could be more costs effective. Are concerns were that we did not want the new patio to settle but we did not want to go over the top on the construction.

It sounds OTT to me, but I haven't seen the site, so it's not fair of me to comment.

However, I would simply build-up the levels using a flexible sub-base and then bed the new stone flags on bed of cement-bound grit sand. I would need to be convinced that using a 100mm thick reinforced slab base was actually needed for such a relatively minor construction project. If it was being trafficked by cars/vans, or if there was a history of sihgnificant settlement/subsidence, then perhaps I might go with this spec, but for minor settlement of an old patio, I think it's over-engineering.