Dig up Existing Conrete for Paving Slabs?

26 Jun 2015
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United Kingdom

I have around 24 sqm of existing concrete about 5 inches thick that provides the base floor as soon as you step out into the garden from my house. Although the existing concrete is stable and appears to be in OK condition it's not level and not suitable for us to just simply lay slabs over the top.

My questions are:-

- Is it essential that you dig up the existing concrete before laying your hardcore/bed for the slabs? I'd like to avoid this if possible as the soil pipe runs straight into the ground for the upstairs toilet, I also have a drain cover for a manhole that I would need to recess and I also do not know the locations of any utility pipes running under ground?

- My understanding is that any new patio will need to sit 150mm underneath the damp proof course of the house and slope away from the property. How can you identify damp proof courses on house that do not show the solid brick work? I have lime render covering the entire house

- With regards to draining away from the property, the width of the concrete is only 2 meters and then you have a retaining wall for a raised garden lawn. Would this be sufficient? I'm thinking the water would just gather at the bottom of the retaining wall?

Ideally I would just like to level the existing concrete, create a hardcore base with enough slope away from the property and lay slabs on top but something is telling me that it's not as simple as that!

Any help or advice would be greatly appreciated. I'll try and post some pictures later.


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show is a picture of the concrete in relation to you patio door,
with a bit of luck you can leave the concrete, you need about 40 to 50mm of wet cement under the new slabs
Thanks for your reply.

I'll get the pictures up tonight so it will hopefully explain things a little better.

From memory, there's only a small 3-4in gap from the concrete base to the patio door step. I'm just very concerned about laying on top due to me not knowing the location of the damp proof course for the house.

Is it correct that patio needs to finish 150mm under DPC?
Ideally Yes 150mm under DPC

That is why i asked for a picture of the patio doors in relation to the concrete
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Here you go mcluma ... photos as requested.

The concrete looks a lot worse than I thought, very stable though with no movement, cheers.
Thanks for the photo's, Having looked at them, i doubt you can go over the concrete with slabs. You concrete already looks to high as it is. but you had already figured that one out.
Thanks for your help, I think I'll go ahead and rip it all up.

Just out of curiosity, how would I identify a DPC on my that property? Also, do you have any advise regarding utilities running under the ground? Would my local authority provide some information?
is that some kind of a timber stop at the bottom of the pebble dash?
if so then its probably under that?
Yeah it's a timber stop, no idea what for, I only just bought the house so couldn't tell you what previous owner did. Can't see any previous fixings to show that it could have been attached to something.
House looks like it has had external insulation done - and the insulators reinstated the waste pipes with loads of elbows:notworthy:
that piece of timber on the wall is used as a starter for the rendering

I do not think its going to take long to take up the concrete, its in a really bad state, get a good breaker and should not be longer than a few hours work

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