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Groundwork & Foundations

Laying flags over existing (aged and worn) concrete

Anonymous user 28/02/2024 - 3.49 PM

Hi, We have a summer house constructed on a concrete slab. There is a section of the slab that comes out in front of the summer house that I would like to make good, and onto which I would like to lay some pavers/flags. This is the first project of this type I am attempting mostly unfamiliar with the processes. The dimensions of this area are: 720mm depth 4200mm width There is then around an 80mm vertical gap from the slab to the doors. So that would seem like plenty of space for flags. So my plan is to pressure wash the surface to clean it and get rid of all loose bits, and then I think I have three possible options. Out of the three below, which it the best option. In all instances, I think I will need to recreate the wooden frame around the area and then: 1) Pour in exterior levelling compound (something like Setcrete?) and then lay the flags on top using mortar 2) Manually level out with fresh concrete (and a bonding agent?) 3) Apply the mortar directly to the existing concrete onto which I can lay the flags (I assume this might not be the best option) Possible 4) As per options 1 or 2, but just use sharp sand and polymeric sand for the joints? Any advice as well as extra tips or gotchas much appreciated. Thanks! Dave

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4 Answers

Anonymous user

I personally would just start with a fresh base to be honest it doesn't look the best, good luck

Answered8 June 2020

GF Groundworks

Rating: 5 out of 5

Wimborne

If the concrete is cracking your sub base is moving so I would start again be a much neater job and last for years hope this helps

Answered10 June 2020

Dream Driveways & Landscaping Ltd

Rating: 2.4 out of 5

Huntingdon

As it is part of an existing summer house base and that has stayed sound and solid i would expect min 100mm of concrete .I would go with a flag rather than a pavior because it covers the whole area .i would just make up the bed to the depth needed rather than.lots of layers which could possibly lift.could possible add sbr additive to the mix for extra strength if needed .5:1 mix on full wet bed .

Answered18 June 2020

Anonymous user

The picture supplied isn’t the best, but looking at what you are attempting is lay a narrow path in front of the shed ? If the existing concrete is not cracked or showing signs of subsidence then I would lay new slabs over remember to remove any green growth etc. Use a sharp sand and builders sand mix which will give strength and will be a easy workable mix.

Answered25 June 2020