Decking excavation depth when replacing paved patio
Posted: Sun Jun 21, 2020 10:16 am
I want to replace my paved patio (cheap 30mm paving slabs) with decking, but I don't want to raise the level too much for various reasons. Ideally it would be about 3" higher than current.
I had one suggestion to deck on 2x2 supports on top of the slabs, but I'm not convinced this is a great idea.
Alternate is to remove the slabs which are likely laid on sand with a mess underneath - where I have dug out it was hardcore (building rubble) with soil mixed in.
I'm thinking if I remove the slabs (30mm) and dig out 175mm, including the 3"(75mm) rise that would leave me with 280mm to play with - 100mm for the decking supports, 25mm for the deck and 150mm for the 6" joists.
That should leave me with 3 cubic metres of material to dispose of.
I could omit the supports and lay the joists directly onto the hardcore underneath I believe, but I'm guessing they'd rot far quicker that way.
Any alternatives I've missed?
I had one suggestion to deck on 2x2 supports on top of the slabs, but I'm not convinced this is a great idea.
Alternate is to remove the slabs which are likely laid on sand with a mess underneath - where I have dug out it was hardcore (building rubble) with soil mixed in.
I'm thinking if I remove the slabs (30mm) and dig out 175mm, including the 3"(75mm) rise that would leave me with 280mm to play with - 100mm for the decking supports, 25mm for the deck and 150mm for the 6" joists.
That should leave me with 3 cubic metres of material to dispose of.
I could omit the supports and lay the joists directly onto the hardcore underneath I believe, but I'm guessing they'd rot far quicker that way.
Any alternatives I've missed?