Subbase - Subbase

[Overworked]

I am using an existing concrete sub base to support an IS patio. I have already removed the existing patio which consisted of crazy paving in broken concrete flags (very ugly) As the sub base has been down now for donkeys years I am confident it should take the weight of the IS However the fall is very much more than 1:60 so I need to build it up especially at the front Where the fall is greatest I have done this with crushed limestone which I intend to compact but I have a problem as I get near to the house where the added layer becomes very thin Assuming I want to keep the maximum depth of the bedding layer to 50mm then in places I would only need to add around 10 - 20mm on top of the existing concrete Is laying an additional concrete layer in this situation satisfactory (maybe after priming the concrete) and what would be the best mix Also is Building sand Ok to use for this Or is there a better soloution

Many thanks

Mike






By the way I have built some planters around the outside of the patio

[Rich H]

Where the layer would be thin just use a thicker bedding layer. I wouldn't go less than 50mm for the made-up sub-base. A few more mixes but better that way.

[Overworked]

Where the layer would be thin just use a thicker bedding layer. I wouldn't go less than 50mm for the made-up sub-base. A few more mixes but better that way.

This would mean that the bedding layer could be as much as 70 - 80 mm in places I would think a dry or moist mix would be needed then Do you agree

Any other implications ?

Mike

[seanandruby]

In Brighton i laid laid 60ml council flags to footpaths. in some places there are high concrete bases that couldn't be touched as it was over basements. we used 16ml re-bar to screed off and laid them on that. all sorts have driven over them and they are still sound 10 years on.