Concrete or slabs

[pacey]

Hi

I am building a dog run 5500 x 4500 (18' x 15') and was going to floor it with concrete. My question is which will be more cost effective? i.e. Concrete flags or a concrete slab?

I thought about flags initially and laying them down on concrete to prevent any movement, but then after reading your greatl website, I thought about forgetting about flags and doing it competely with one slab of concrete.

What thickness of concrete would I use (100 or 150)?
Would I need expansion joints?
Would I need to use a sub base?

Can you give me any advise

[Tony McC]

Assuming there's no vehicular traffic and that you have a sub-base or a decent sub-grade, then 100mm of concrete would be fine.

I'd be tempted to split the slab into 4 bays, each roughly 2.75m x 2.25m using crack control joints because we try to keep individual bays to less than 20m² and the longets axis to not more than 30 times the thickness of the slab (3m for a 100mm slab or 4.5m for 150mm). An alternative strategy would be to use a 150mm slab and just one, central control joint giving two bays at 4.5m x 2.75m.

The existing ground conditions dictate how relevant a sub-base would be. If you have a really sound sub-grade that can be accurately regulated, then you might be able to get away without a sub-base, but most projects do benefit for having one installed, even if it's only 75mm or so.

Best piece of advice I can give? Don't forget to use a damp proof membrane beneath the concrete.