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Replacing monoblock with lawn

Afternoon GWers! I'm mid-way through buying a new house. Its previous owners paved over its entire back garden with monoblock. Having done some research, I believe the surface will be:
  1. Monoblocks (top layer)
  2. 50mm sharp sand
  3. 150mm type 1 hardcore
I want to replace the monoblock with lawn and I'm trying to work out what I need to do. Initially, my plan was to remove the monoblocks, add top soil, and lay the lawn. However, type 1 isn't permeable so this will cause drainage problems.

I think there are two options:
  1. Remove monoblocks, decompact type 1, add top soil, and lay lawn.
  2. Remove monoblocks and type 1 layer, add top soil, and lay lawn.
Option 1 means not excavating 150mm of concrete, which is attractive, but I'd rather get this right first time.

So what do you think?


  • FairygirlFairygirl Posts: 54,754
    I think it would better to remove the hardcore, but if you think you can break it up well enough to allow good drainage, then it might well be ok.
    Grass doesn't need a huge depth of soil to grow, but it also depends on your climate. In very dry areas, it might be better to have less drainage anyway!
    You'd have to dig down and see exactly what it's like below the blocks and hardcore, and make a judgement.
    You'll also need an edging to contain the new soil and turf, unless there's a border you can leave in place. 
    It's a place where beautiful isn't enough of a word....

    I live in west central Scotland - not where that photo is...
  • Thanks for the tips, Fairygirl. I'm on the west coast of Scotland so definitely not a dry area! I guess I'll dig down, see what's there, and assess. 
  • TopbirdTopbird Posts: 8,329
    edited September 2022
    I think (but I don't know...) that leaving the hardcore in place would not be a good idea. We get a lot of postings on here from people who have moved into new builds and who have gardens full of compacted soil and builders' rubble. They often seem to have problems with lawns.

    Do you definitely need a lawn? What you have sounds might be a good foundation for a gravel garden if you can loosen the hardcore.

    Just a thought - but if you need somewhere for kids to play footie then you need a lawn...
    Heaven is ... sitting in the garden with a G&T and a cat while watching the sun go down
  • FairygirlFairygirl Posts: 54,754
    Ah - similar to me - probably slightly wetter. It's why I always ask where people are. Many folk have no understanding of the growing/climactic differences around the country, and it has a huge bearing on how you proceed  :)
    I created a lawn here about 8 years ago, which had been a fully paved/gravelled area. I did very little to it. Lifted the paving, put an edging round it, then added soil, with the remaining gravel/grit sand mixed through it. Great for our climate as the gravel mitigated the wet stuff .  :)
    It's a place where beautiful isn't enough of a word....

    I live in west central Scotland - not where that photo is...
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