How to fill gap between concrete and garage masonry wall?

ScimmysFury

Hi, my garage has a concrete slab floor and besser block wall. There are some large cracks (20 - 40mm) between the concrete slab and the wall. See photos. How can I fill this in and seal it.

I was thinking either use grout or expanding foam until 10mm below the surface then some flexible concrete sealant (Sikaflex etc) to the surface. Or maybe a foam backer rod and then sealant on top of that. Ideally I would just grout to the surface but it if moves again this will obviously crack again.

I realise this doesn't fix the structural issues but we will replace the shed in the next 3-5 years anyway.

There are also some smaller cracks between the besser blocks in the vertcal walls and I plan to use expanding foam or flexible sealant on these.

Thanks

Kane.

EricL

Hello @ScimmysFury

Welcome to the Bunnings Workshop community. It's wonderful to have you join us, and thanks for sharing your question about your floor gap.

Due to the size of the gap, I propose using Sikaflex PRO-3 Purform (special order) in combination with https://www.bunnings.com.au/sika-10-x-50mm-6m-abelflex-expansion-joint-filler-foam_p1063340 . I propose clearing the gap as best as possible and folding the Abelflex so that it can fit into the large gaps without sinking. I recommend pushing the foam filler just 5mm deep so that there is space for the Sikaflex to flow and fill at the top. Placing the Abelflex too deep will consume too much of the Sikaflex filler.

In regards to the wall you can use the same Sikaflex product, but I suggest using https://www.bunnings.com.au/moroday-15mm-x-5m-white-gap-filler-rod_p4061877 instead of the Abelflex.

Please make sure to wear disposable gloves when handling the Sikaflex filler.

If you need further assistance, please let us know.

Eric