Decking excavation depth when replacing paved patio Ask questions and find answers on all your decking problems and issues

[rick1632]

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?

[stoneyboy]

Hi rick1632
Have a look at composite decking joists, they will be more expensive than timber but you could lay them direct on the existing patio saving a lot of digging.
Regards S

[stoneyboy]

Hi rick1632
Have a look at composite decking joists, they will be more expensive than timber but you could lay them direct on the existing patio saving a lot of digging.
Regards S