Ask a tradesman

Garages & Sheds

Expansion gaps in a concrete slab

Hello, I'm building some outdoor kennels and runs and I have worked out that my concrete base will be approx 150mm deep,14.5m in length and 6m in width so 87sqm.

I've been advised to incorporate expansion gaps roughly every 5m as slabs over 6m x 6m need them. Roughly how wide do these gaps need to be?

I know people like to try and 'centre' them within the slab for aesthetic reasons but my concern is that dogs are going to be using these space all the time so is it possible to have a top covering over them and if so what material is advisable to use?

Many thanks you for your help.

4 Answers from MyBuilder tradespeople

Best Answer

I would put in 3no expansion gaps, along the 14.5m run.
Its a fibre based board, I would do the 2 outside base one day, 2nd day put your expansion board against the 2 edges then cast your middle bay.
Its neater to use a steel float with a curved edge and run it along all your edges.
You dont need a top covering to conceal the board, it will compress to about 15mm ,and will hardly be noticable.


Answered 2nd Jun 2011

I know that construction companies on long walls have to have expansion gaps, and that afterwards they disguise the fact by using an external coloured silicone, you could also place a length of say 10mm width foam in the gap initially and then silicone on top of this.

I don't know if this is the correct solution, but it sounds like it would be suitable.


Answered 2nd Jun 2011

I've done concrete on huge warehouses and airports,these massive areas require expansion rails,shuter up the outside,put steel mesh in,fill with wet concrete,then powefloat when concrete starts to go tacky,if you want 1 expansion use 10mmx100mm foam in the center,your slab is in essence a 14m strip of concrete,not a big area that needs expansions


Answered 3rd Jun 2011

Use a waterproof mastic .


Answered 2nd Jun 2011

Post your job to find high quality tradesmen and get free quotes

Can’t find an answer? Ask a new question

Question Categories