dsaunders

Thanks - I guess I meant it would be cheaper if not comparing like for like, and trying to then workout the cost increase vs benefit of the improved performance. Thanks, I'll have a read through.

Been a while but I thought it may be useful to update on this..... This post was incredibly helpful and led us to discussing the issue with Graham at Town and Country Vibro as above who put us in touch with Lindsay Baxter (LB) design, and following a little back and forth and some reassurance from LB that he is confident this will work despite our other SE stating it wouldn't, we ended up having vibro compaction completed instead of piling. Certainly worth exploring if you find yourself in a similiar situation being told that piling is the only option - it was apparent that our SE at the time was not familiar in vibro compaction and therefore understandbly was shying away from anything other than piling.

This is our third self build, and hopefully third time lucky will make it our last! This time we're opting for a timber frame with much more consideration given to fabric of the building to ensure it performs well. We hadn't considered different foundations as the budget is non-existent and assumed anything other than standard strip footings will be silly expensive. I've looked into what I can and spoken to a few insulated raft suppliers and their general consensus is that we will end up at cost parity when comparing with strip footings and concrete slab. However, this doesn't take into account muckaway. Surely the insulated raft will cost us more when factoring this in? Trying to get an answer on this is difficult and appreciate varying factors will influence cost, but to do traditional strip footings I have a local groundworker who is great on the machine, but not the type to sit and cost items up so I cannot get a true comparison of cost. His simple view is that an insulated raft is very expensive and overkill - however, I can't help feel there's an element here that his experience/knowledge in traditional methods means he's slightly biased. A little bit of a crossroads now as I need to instruct the engineer, if opting for traditiional trench fill then it would be one engineer, if opting for insulated raft then that is included by the supplier. Until the engineer advises requirements on trench fill, difficult to know the cost difference, however ground survey has been done and groundworker has said our ground is very good, be surprised if building control want more than 500mm deep but with existing trees being in the plot it may throw a curveball. I suppose the question I'm trying to ask here, or confirm my thinking is - surely an insualted raft will be more expensive than the traditional trench fill if we have good ground? And are the benefits of insulation and omitting cold bridges worth the extra; how much is the extra and what is the payback etc. We don't want to opt for a well performing timber frame and then feel we've not paid enough attention to the foundations, but of course there are budget constraints to work within! Thanks in advance.

Hello, we are currently awaiting our SE to complete design for our rc ground beam and pile layout. I just wanted to write here to get a second opinion hopefully, as currently it looks to be a very expensive option! Ultimately I trust he knows best, after all he is the expert, but considered there was nothing lost putting it here for some thoughts. So we had some trial holes completed, findings were not great, SE came back another time as it was variable between different locations but it was worse second time around. Had to arrange boreholes, one at 10m and one at 20m. Both borehole results were wet, white chalk (recovered as putty chalk). Our builder suggested a raft, and after reading on this forum and seeing they appear very popular, I suggested this to the SE but he advised our ground conditions vary too much for a raft? So now we have seen his assessment and load capacity possibility, the report suggests 16m and 20m piling ( not sure if they go as deep as that, or just his assessment ), which will be a huge increase in our quotes received for 6m. I appreciate we’re still awaiting his design but any thoughts are welcomed.