Browse Forums Building A New House 1 Aug 02, 2006 9:40 pm We're in the negotiation phase of a building contract. The first tender supplied by the builder has indicated that the cost of foundations and site works will be significantly higher than normal, depite the fact that the block is dead flat and 'S' grade soil.
When I queried the builder on this, he told me that a dead flat block made site costs expensive because when building on a sloped block, the cut could be used to fill the lower areas, but on a flat block it was necessary to remove the top 30cm (to ensure that all vegetation was removed), then import fill to replace it, compact it and then the foundations would need to be deeper to account for the unstable new fill. This seems strange to me for two reasons; 1) I've always been told that a flat block with S grade soil was the absolute cheapest for construction 2) Surely an amount of soil has to be removed anyway, as the slab sits partially below the ground doesn't it? Is anyone able to clarify this for me? Re: Foundations on a flat block more expensive? 2Aug 03, 2006 12:11 am Was there a soil test and engineering design done for this work?
Maybe there is a particular site condition that requires that method? Vegetation is usually the grass and would not need compacted fill under the raft slab - that is the whole purpose of a slab on ground - it bears on the concrete beams and the slab bits 'float' (like a raft) in between on soil of much lessor bearing pressure. It is a bit hard (and harsh) to judge from a distance without that information. If there is no soil test and engineer design calling for the 30cm cut with compacted fill then ask for one. Also check with the local building surveyor to see if that is normal in that area. Re: Foundations on a flat block more expensive? 3Apr 12, 2014 9:03 am buildingnew We're in the negotiation phase of a building contract. The first tender supplied by the builder has indicated that the cost of foundations and site works will be significantly higher than normal, depite the fact that the block is dead flat and 'S' grade soil. When I queried the builder on this, he told me that a dead flat block made site costs expensive because when building on a sloped block, the cut could be used to fill the lower areas, but on a flat block it was necessary to remove the top 30cm (to ensure that all vegetation was removed), then import fill to replace it, compact it and then the foundations would need to be deeper to account for the unstable new fill. This seems strange to me for two reasons; 1) I've always been told that a flat block with S grade soil was the absolute cheapest for construction 2) Surely an amount of soil has to be removed anyway, as the slab sits partially below the ground doesn't it? Is anyone able to clarify this for me? That doesn't sound right to me, get a hold of the soil report and foundation design I assume you have paid for them so they are yours. Cutting and filling is almost always more expensive for the earthworks and deeper foundations. For most slabs a site scrap to remove vegetation is required. our situation was a bit of a guinea pig in that structural work by the previous builder was defective and the house was almost completed, and our structural engineer… 1 4965 I would suggest you simply go and talk to council about your proposal, most councils are getting onboard with ancillary dwellings. There is no benefit in keeping it… 1 4106 I think I know the answer but just checking to see if anyone has had experience with it. I want to build a small 20 square metre retreat in my backyard, it will have a… 0 13880 |