We have a lot of surface water on our site thanks to building on Sandstone rock base so the soil above is quite damp. I am also putting in some mitigation to push water away from the site and the height of the house will be up above the highest wet point. There will be piering to support the slab now the builder tells me that to do the pirering he is afraid that if tehy drill the day later the hole will have water in it or the sides of the hole may collapse, all more work and "Cost". So hie is proposing to use grout injected piers. So you drill and then inject the concrete in at the same time. Apparently this gives concrete at 40-50 Mpa.
Does anyone know the difference in cost between normal piering and grout injected. It is a per lineal metre quote.
Thanks
Dan C