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Posted: Tue Mar 08, 2016 5:10 pm
by benjani82
I'm in the process of laying a concrete base to build a log cabin on, the ground slopes away in one corner (15 inches lower than the highest point). I have built a frame of 8x2 tanalised timber and filled it with MOT type 1 which will be compacted and was planning on laying 150mm of C20 concrete on that. My concern is that the low corner will only be supported by the timber frame, but if that rots over time the MOT would be unsupported, so am I best to dig out the perimeter MOT to allow the concrete to surround the sub-base, or to build a retaining wall in place of the timber for a more permanent solution?

Posted: Tue Mar 08, 2016 6:31 pm
by lutonlagerlout
you need a toe on the concrete,so that the concrete forms a vertical as well as a slab
IMHO C20 is too weak a mix for this,C.30 or C.35 with mesh
LLL

Posted: Thu Mar 10, 2016 5:19 pm
by benjani82
Thanks for the advice, I've gone for C35 with mesh and will leave a 200mm gap between the MOT and the shuttering to allow for the concrete to go down to the floor on the areas where the level drops. One final question, as the MOT isn't currently supported at the lower end (until the concrete goes in ) will this cause an issue when I compact it, will it all just fall away and hit the shuttering, or should it stay in place?