Log cabin base - Soft ground

[ray100]

Will be errecting a log cabin in garden, the interlocking 34mm thick timber type that is common now but the site is tending to be soft. The top soil is about 100mm and then to starts to change to clay type soil with a bit of a colour change which is quite noticeable by 200mm depth. A long 13mm motar chisel can be pushed in the ground with a firm but reasonable hand presure until about 500 mm deep. A small hole dug shows that under the top 50/100mm layer it is damp and will easily mold if a finger is pressed in. A sample mixed with water will easily mold and set rock hard. At 500mm the hole showed that the ground was firm but not before. Banging it down at say 150/200mm to compress tends to make it a bit spingy. It is not a sticky clay. Generally the garden soil on whole plot does not drain well.
This type of building is heavier than a shed and the contains will be on shelves and heavy.
A contractor has suggested concrete base100mm minimum thick in centre with 150mm edges. Also put down some scalpings say up to 100mm. Put steel mesh in concrete.No mention of a dpc sheet under concrete as suggested on this site. Required? Sand blinding? I expect base to finish about 50mm above surrounding grass,
What is opinion of this proposal as do not want it to sink or tilt giving problems with doors etc. Would a geotextile material help?100mm concrete path around house has sunk20/25mm! Didn't realy want concrete slab like this as may not always want building on this site but this appears to be suggestion of chalet suppliers.
Should I go with this option or is there something better. Any suggestions very welcome. Many thanks. Sorry for long post.

[lutonlagerlout]

it is pretty much industry standard to put log cabins on a raft construction as your builder has mentioned

dpm is an upgrade and also ,maybe make the whole thing 150mm thick with steel mesh in it on 100 MM type 1
we are doing 1 on sandy ground in a few weeks and we will be doing a raft there
LLL

[seanandruby]

maybe strip foundation. with block and beam, or timber joists if you are thinking of dismantling in the future. Any load bearing interior walls would also need strip foundation.