Landscaper patio question - am I being duped?

[Herewegoagain22]

I've got a landscaper doing my garden right now, he's laying a new Indian sandstone patio for me. I've seen his work on his website and he's got some great Google reviews and testimonials.

He's laying the new patio over existing slabs (which have been down for well over 10 years), he said the existing slabs are in good condition and will have done the majority of their moving way before now. He's cleaned and prepped the area and added a layer of concrete mix and has been laying the slabs. It looks great. But I told a friend about this and she was horrified that he hadn't lifted the existing slabs, and now I'm worried about it (but I'm no landscaper and that is what I'm paying him to do). I got another quote previous to using who I'm using and he also suggested laying over existing slabs.

What do you think? I am mega stressed right now in general and now I'm worried I could be paying all this money for something that isn't right and I have no idea!

* He's laying the new patio over existing slabs (which have been down for well over 10 years), he said the existing slabs are in good condition and will have done the majority of their moving way before now.*

^Laying over existing slabs? No way would I accept this.

I don’t know, but unless your friend is a landscaper, I’d be inclined to trust the professionals myself

My dh does landscaping he says as long as it stats below the damp course it's OK the trouble is the patio is higher now so will that affect the house? It's probably OK as long as the concrete layer wasn't too thick

*stays

@Whinginadeville sorry for my ignorance but what's the 'damp course'?

It sounds like it could work quite well. He’s obviously treating them as hard core. My worry would be if you have problems down the line is he still going to be in existence to remedy the issue?

www.baysidepavers.com/blog/2018/5/26/what-to-know-about-installing-patio-pavers-over-concrete

Plus make sure he doesn’t concrete over any air bricks. A PP was commenting about the damp course. You don’t want to go too high against the external wall as otherwise you could cause damp
by blocking the ventilation. If the patio had dropped you might be okay.

Any idea how thick the mortar layer was?
How were the original slabs laid? Sand or mortar base?
Is the patio up against the house?

In theory, it might be that a thick enough layer of mortar will hold the layers together and spread any load over the old patio. You would normally lay over a subbase etc but I suppose taking it all up and disposing of it could add a significant cost depending on size. What reason was given for laying over the old patio?

[quote Herewegoagain22]@Whinginadeville sorry for my ignorance but what's the 'damp course'? [/quote]
The damp proof course

I've just checked and it is below the damp course, it has been laid up against the side of the house. I don't know how thick the mortar layer was, as a big part of it was done by the time I came home from work! I've messaged him as I want to ask a few questions about other things. Is there anything I should ask him? I'm really worried now, it's making me so anxious

Honestly it sounds like he just couldn't be bothered removing them given the slabs are heavy, and cost money to be disposed of.

When we had a patio laid last year, the old patio was lifted and a membrane thing laid and prepped before it was done.

A couple of companies suggested leaving the old patio in place and laying the new one on top, but that would have brought it in love with the house, and I was worried about what would happen if it rained if we did it that way.

Saying that if your damp course is above the top level of the new patio, it should be fine.

These comments from builders on a similar question might be helpful
www.mybuilder.com/questions/v/15610/paving-over-existing-paving-slabs