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Garages & Sheds Question
How thick should a concrete slab foundation be?
Hello, I'm building some outdoor kennels and runs and I have worked out that I will need a concrete base of 14.5m in length and 6.5m in width so 94.25sqm. What depth should the concrete go down to and how thick should the slab be? Also, should I use roughly 150mm of hardcore? Will the concrete slab need to be reinforced
and sit on two footings etc or will sheet reinforcing mesh be sufficient enough to stop cracking.
Thank you for your help.
Thanks for both your comments! - Pro Finishing Services would you mind explaining expansion gaps a little more? what material should I use for them?
your right base up 150mm h/core leaving it 50mm below ground ,pour 150mm slab with mesh lapped @250mm giving you a finished slab sitting 100mm off ground ,also put dpm down b4 pour under slab as extra protection you will need approx 14.5m concrete for this slab
Answered 1st Jun 2011
Thats a good old run, you should look at expansion gaps every 5mtrs, this area will absord a lot of heat in summer!!!
A surface are of this size will expand and contract in summer winter. I would look what products are available with your local builders merchants, some use stiff rubber hose, some use silicone based seals, Divide your area up when when laying and put these between your concrete pads, flush with the surface. This should help stop the cracks and bursting, the seals will absorb some of the movement. Maybe incorporate them into your drainage channnels!!. You have probably driven over them everytime you cross a bridge, these are for the bridge expansion. Same principal.
Answered 1st Jun 2011
You want to measure down from what you would like as your finished floor height 450mm. That's 150mm of crush, wacker down, 50mm sand, wacker again, dpm, 100mm kingspan, then 150mm concrete. Place your mesh over 20msq (approx 4 linnear mts) lifted 50mm off the insulation, leave a 15mm expansion gap then do the same again with next mesh. You could also pour a 100mm slab if you wanted. I would also suggest wet under floor heating if your looking to heat the place. Would be much cheaper than radiators and gives the added possibility of solar heating.
Hope that helps
Just goto Travis Perkins and ask them for slab expansion strips. Can't remember the exact name of them. Just like a soft insulation
Answered 2nd Jun 2011