How to fix height difference between path and shed slab?

ASQ

Hi all

I wanted to reach out for some advice regarding a recent project. I've had a shed slab poured next to an existing concrete footpath. The new slab is approximately 45mm higher than the footpath and is about 1470mm deep. Since the shed depth will be 1510mm, it will overhang the slab by approximately 40mm (pics attached).

Given this situation, I'm wondering what the best course of action would be. Would you recommend concreting in the difference, filling it in with something else, or leaving it as-is with a slight gap?

Many thanks for your help!

Slab widthSlab heightSlab depth

MitchellMc

Welcome to the Bunnings Workshop community @ASQ. It's fantastic to have you join us, and many thanks for your question about adjusting a slab.

In this situation, the most reliable solution is to add to the existing slab rather than trying to simply fill or leave a gap. Grafting on an additional piece of concrete can be tricky, but if done correctly, it will be far more durable and less prone to cracking. Since the lower slabs are separate and there’s an expansion joint, you will need to create two separate grafted sections to match the existing heights. 

Start by drilling vertical holes into the lower slab where the new concrete will join, and also drill horizontal holes into the raised slab. Into these holes, insert and glue reo rods using a product like Ramset 300ml Chemset UltraFix Plus. This will provide solid tie points. Then, run additional lengths of reo rod along the sides of the new sections and tie them to the inserted rods with tie wire. Once the reinforcement is in place, you can form up the grafted sections and pour the concrete. This method ensures the new sections are mechanically tied to the existing slabs and will reduce the risk of cracking or movement over time.

I've created the rendering below to illustrate.

Please let me know if you have any questions.

Mitchell