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Groundwork & Foundations

Do I need rebar/wire for concrete slab?

Ria Dobbie 20/07/2026 - 8.09 AM

We have removed a full peice of concrete slab out of the centre of a floor area (external) down to the mud. We’ve refilled with a few inches of hardcore as it was a raised floor area, and now are ready to refill with repair concrete (using SIKa LA repair concrete). . The rest of the floor did not have rebar/mesh was just created with concrete that had a lot of pebbles in. Can the repair concrete we have be used straight on top of the hardcore and adhere to the sides where the slab was cut out, or do we need to prepare the base of the area differently? Any advice would be gratefully received :)

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6 Answers

Anonymous user

Hi you need a sheet of a1342 rebar meash doesn't have to be thick

Answered18 July 2026

Anonymous user

Don’t pour it onto loose stones. Pack the hardcore down first, clean the edges of the old concrete, wet them slightly, then pour the new concrete. That should give you a much better repair.

Answered16 July 2026

RPG contractors

Rating: 4.5 out of 5

Westbury

See how deep the hard core is on a few test sections if ok wacker plate it down and add mesh to the designated area sat on suitable support to keep it a off the ground for the concrete to set around so it’s tied but you may also need expansion joints pending on the job

Answered16 July 2026

Brickwork solutions ltd

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St Helens

I'm assuming that with you using a concrete repair product that it is only a small repair as the cost of the stuff is prohibitive. If it's a small repair just clean up the edges, sometimes you have to use the primer that comes with the product. No re bar is needed for a small repair. If you're looking at a large repair I would cut out all the damaged concrete, compact the ground which i suspect will already be compact, drill and epoxy steel tie rods into existing concrete then drop a small sheet of mesh in, tied with wire to the tie rods. Then just use sand cement stone mix to fill the hole.

Answered16 July 2026

Anonymous user

Best solution if the old slab has no rebar in it I would drill holes into the surouding concrete 100mm deep spaced out 300mm apart and put rebar into the hole with at least 200mm left out of the side so 100mm in the hole then 200mm sticking out, you could leave it like that poor your slab that way the new concrete has something to grip to and bind new concrete to old. If u don't so that then the two slabs won't bond to each other and u risk movement. You could lay a rebar sheet on top and tie it to the bars that are pretruding if you wanted for extra strength but it would be fine without the sheet as well.

Answered20 July 2026

Anonymous user

Your question is a big vague in relation to depths. But, standard practice when joining new to old concrete, is to always drill and dowel existing concrete with a layer of mesh. This will eradicate any separation and/or individual movement of finished slabs.

Answered20 July 2026