I'm having a large concrete deck built which will be about 30" high at the highest point. The question I have is what should it be filled with, compacted soil or rock? There will be concrete walls and a six inch, steel reinforced slab on top and the top surface will be slate tiles. Originally the contracter suggested using drainage rock but now favors soil which is available at no cost. Would the compacted soil be suitable to provide a base for the concrete slab? Appreciate any suggestions.
Substrate for raised concrete deck
- Thread starter Maryberry
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CurlyDave
Elite Member
I would go with compacted drain rock.
Sure, dirt is free, but if the dirt is even a little bit expansive it is going to crack your new concrete deck.
You can prevent settling by backfilling in lifts and compacting with a plate compactor between lifts, but you can never beat expansion.
Sure, dirt is free, but if the dirt is even a little bit expansive it is going to crack your new concrete deck.
You can prevent settling by backfilling in lifts and compacting with a plate compactor between lifts, but you can never beat expansion.
CurlyDave
Elite Member
Should be close to least expensive.
Around here we can get something called "ballast" which is angular rock screened to be +3/4" -1.5". This works just fine for drain rock and is sometimes less than 3/4" round rock. The angular rock needs more compaction, but the round rock needs some compaction anyway.
Around here we can get something called "ballast" which is angular rock screened to be +3/4" -1.5". This works just fine for drain rock and is sometimes less than 3/4" round rock. The angular rock needs more compaction, but the round rock needs some compaction anyway.
