Existing patio and base to form base of conservatory

[Herbert1]

I have a patio aprox 60mm very hard slabs in way of crazy paving. This has gone down on about 6-8 inches of ballast mix. Was very hard to break up using breaker where foundations went.

I am aprox 200mm below dpc level. Do I need to break all this solid base up considering I need to add insulation, dpm screed?

Base been down 15 plus years and no signs of movement or cracks.

Thanks

 

[r896neo]

Whilst it seems solid and may well be It doesn't take much movement to break up a screed. It's up to you if its a diy project but there is no way someone doing it professionally would risk it or recommend you to go ahead. Just break it up and do it properly.

 

[Herbert1]

I had every intention of breaking it up in the first place but thought I would ask the question just to see if it was deemed excessive and making unnecessary work, Over to TP's tomorrow for a bigger breaker.

Cheers

 

[Deluks]

You could be a bit cheeky and go with dpm/insulation/concrete and omit the screed. But you will need to work the concrete to get it as flat as poss and end up putting down self levelling compound.

I don't see a reason why you can't remove the slabs and hire a wacker to re-compact the existing hardcore.

How high is your current floor above dpc?