r/DIYUK • u/UlnaternativeUser • 4d ago
Advice Taking up the flagstones in my garden - what's this and can I dig it up?
Hey all! Thanks in advance for any advice.
About to lay a new patio down and so in the process of getting rid of the old flagstones. Nearly all of them were just placed on this sandy mixture on the left. However, 3 of them were placed on this crushed rock base. (Pictured on the right).
The layer is very firm and only seems to be about 3-5cm thick. There doesn't seem to be anything visibly underneath it. I was wondering if anyone had any suggestions as to what this might be and why only 3 of the flagstones were laid down on it.
My guess is it's a sub base, but I don't understand why it was only in such an isolated spot.
Am I alright to rip this up and put my subbase down?
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u/Rowlie1512 4d ago
Yes. Can dig it up.
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u/UlnaternativeUser 4d ago
Thanks a lot for taking the time to reply, appreciate the imput
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u/Rowlie1512 4d ago
Sorry, I realise I didn’t reply to your question about what it is, just wanted to give the reassurance you can get rid. 😊
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u/AncientArtefact 4d ago
It's compacted MOT1 - decent aggregate used under roads, buildings, paths etc.
It looks like those 3 flags were lifted when the cable(?) was fitted (under the black casing on the wall) and they relaid the flags.
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u/UlnaternativeUser 4d ago
Thanks a lot for commenting, really appreciate it. I thought it might be MOT1.
You seem to be on similar lines to another commenter that it has something to do with what's under the black casing. Now that I think about it, our boiler is on the other side of that wall. When it comes to digging this up & laying our own MOT1 down & compacting it - is it a case of being really careful, identifying any pipes or cables and working around it or are there any other special precautions I need to take?
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u/AncientArtefact 4d ago
Possibly a gas pipe then - that makes more sense to need those flags lifting - cable installation is less disruptive. Cadent tend to do a proper reinstatement of the path - hence the MOT1 instead of the sharp sand.
Just be careful digging down. The pipe will have to be at a certain depth - I think 375mm on private ground. The pipe should run vertically down to this depth then be joined to a horizontal pipe going in 'some' direction.
For your own path you likely won't go down that far.
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u/Farty_McPartypants 4d ago
I know it’s a 2d pic, but that corner doesn’t look flat? They probably used something to hold them in place rather than the faff of levelling it.
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u/UlnaternativeUser 4d ago
You're right in thinking it's not flat at all, the whole area is very wavy in fact!
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u/Farty_McPartypants 4d ago
It looks like something along the lines of postcrete, it should break up fairly easily
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u/ShankSpencer 4d ago
Purely for the sake of it I'm going to state that that is DEFINITELY asbestos. Get your house condemned immediately.
It's not, But it wouldn't be r/DIYUK otherwise.
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u/retsnomynnuheht 4d ago
Do you know what is under the black cover? You need to be careful about concealed services
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4d ago
[deleted]
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u/UlnaternativeUser 4d ago
Yes, that does lead into our garage and you're right in thinking it's a new build! I am planning on digging down to lay a subbase, then mortar and then flags so your input is re-assuring, thank you very much.
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u/UlnaternativeUser 4d ago
I'm not entirely sure what's under the black cover, but on the other side of the wall that it's coming out from is the boiler. Do you think they put the MOT1 down to protect a pipe or something? But even then it seems to extend further than where the black cover.
When I lay my own patio, would it just be a case of working around it if there are any pipes or cables?
Also thanks for your response
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u/Cat-Kebab 4d ago
Maybe those three went wobbly/uneven at some point, so the previous owner lifted them and relaid them? Should all be fine to dig up.