Page 1 of 1
Posted: Fri May 08, 2009 6:41 pm
by wez
Firstly, great site Tony. I cannot seem to find a page dealing with my issue, although there is a similar post in the forum it does exactly ressolve my issue either.
I am thinking about constructing a patio (~25m2) at the rear of my garden. I have a concrete path running down the length and across the back of where my patio would lie.
My question is (I bet you've guessed already!), do I need to dig up the concrete or can I take the lazy way out and build the sub-base level up to the path and then lay on top of that.
My logic says if the sub-base is whacked down properly it shouldn't be an issue, but I'm concerned I may make things harder for myself in the long run.
Thanks
Alan
Posted: Fri May 08, 2009 6:49 pm
by wez
Just to clarify patio is for light use and will almost certainly be used for a large shed.
The path is solid with no sign of cracks.
Posted: Fri May 08, 2009 7:56 pm
by Rich H
As long as your finished paving height is 150mm below DPC it doesn't matter provided you end up with a firm base to work on.
However, putting a sub-base on top of a concrete path doesn't make sense - just use the bedding course. Otherwise you'll end up with a rigid concrete layer, a granular compacted layer then another rigid layer: the bedding course. Not the end of the world for light use but not ideal either.
Posted: Fri May 08, 2009 8:29 pm
by wez
Thanks for telling me what I wanted to hear Rich. 
Saves me a whole lot of hassle. I'll hopefully get it done this summer, got a fence to put in first so I can level the flower bed before putting in the patio. The neighbours put the fence in (before I moved in) but didn't sink it to the level of my garden! 
No DPC to worry about as it's well away from the house.
Posted: Sat May 09, 2009 4:26 pm
by Tony McC
There *is* a page: in fact, it's a FAQ..... Laying over existing
Posted: Sat May 09, 2009 6:31 pm
by wez
I knew that would happen. 
Doesn't quite answer my specific question. My main concern was whether it was okay to 'mix' surfaces. All the same I'm not going to argue with the gaffer. :;):
Apprectate Rich's comments, as I mentioned, the pavement (which has been down many years at a guess) shows no cracking and is in excellent condition. I assume it will be fine to pave over.
I want to do the job properly so if it means it needs to come up then so be it. Opinions welcome.
Posted: Mon May 11, 2009 9:42 am
by Tony McC
Mix surfaces? Do you mean "mix substrates" in that part of your planned patio will lie over the existing path and part will be over a new sub-base?
If so there's no real problem with that strategy.
Posted: Tue May 12, 2009 4:25 pm
by wez
Yes I did mean mix substrates. Thanks for the advice. The more I think about it, it may be worth digging the path up at least it'll give me a 'clean' canvas to work with, and will make future changes to the garden easier.
