Hi All,

I am laying down a concrete base for my 16' x 10' timber shed /
workshop.

I have dug down 5 inches below ground level and am planning to lay:

4 inches of compacted hardcore
A layer of sand
Damp proof membrane
Then 4 inches of concrete (so the concrete should finish about 3
inches above ground level.)

I have a few questions which I would be grateful if anyone can
answer:-

1) Should I lay the form board / shuttering down before I lay the
hardcore? (This means boards need to be about 8 inches high). Or
should I lay the hardcore first, then 4 inch high boards (nailed to
stakes driven into the ground). I am worried that if I put the boards
down first, they may split when compacting the hard core with a
whacker plate.
2) Is a 19mm thick board ok to use (for the shuttering)
3) What do I do with the damp proof membrane after the concrete has
set - should I just cut the edge of it flush with the concrete?

Any help would be appreciated!
Thanks,
Rob