[rogertb]

Hi chaps, I have a new allotment, in the corner are the remains of the floor of a pig sty, this consists of several large slabs of concrete, over the years these have cracked and sunk into different levels/angles. It will be impractical/impossible to remove them so I thought I'd deck over it and use the deck as a base for a small shed and greenhouse ... any comments on the proposal so far will be very welcome.

Now I thought I'd make a frame to attach the decking boards to, sit the frame on 6" x 6" posts in each corner (size of deck 13' x 9') ... now the dilemma, I understand that concrete is not allowed to be used on the site. I was thinking of  digging holes into the earth, a layer of sand in the bottom, a couple of bricks on top of the sand and then sit the posts on the bricks, fill in all around and tamp down ... sit the frame on top, level it by removing/adding to the sand and then secure the frame to the posts with screws ... is this really a bad idea ?

Best Roger
 

[bravemurphy]

rather than dig holes can you knock the posts in.

Or you can get the metal bits that knock in the ground and fit the post inside them.

[8doubles]

Metaposts will continue to sink into the ground with a shedful of tools on top of them, they are designed to go into the ground easily.

I would use your original idea but substitute half a concrete* block for the bricks.

* assuming the ban is on poured concrete not blocks and slabs.

A full concrete block at surface level would be better, then a bit of damp course then your woodwork.
You could tie the decking base  down to the old concrete slab with flexible metal band from the builders merchants.

[rogertb]

Thanks both ... having spent some time 'on-site' clearing off the soil from atop the concrete, it's bigger than I first thought. I think I might be able to plug and screw some 'bearers' into the existing slab at all corner points (as it now needs to be "L" shaped), varying in thickness to get them level and then attach the frame to the bearers ... what fun ... good of you both to take the time.

Roger

[jrko]

Metpost make some metal bases specifically for bolting to concrete with expanding bolts

Hope it goes well