Do I need to re-dig patio foundations?

1 Mar 2018
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United Kingdom
Hi there,

New to this amazing site and hoping you are able to help as I embark on my first proper landscaping project - laying a patio and building a retaining gabion wall.

I am about to lay some paving in my garden, on an area which is currently tarmac.

I was planning on digging down 30cm and then adding 20cm of compacted hardcore prior to the mortar for the slabs.

My question is - assuming the previous owner laid a foundation of hardcore for the tarmac (which I will check when it is up), do I need to dig it out and re-lay my own hardcore? Or can I get away with re-using that which is already there?

Don't want to cut corners but at the same time it seems silly to dig up something and replace it with exactly the same thing? There are other areas of the garden which are 'virgin' and which I will be digging out and treating as I described above.

Any help very gratefully accepted.


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Assuming there is hardcore down there, you may well need to just re-compact it when you take off the tarmac layer. Check how deep they laid it though, as it may have been a cheap job.

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