Concrete thickness

[Thrashsmith]

My workshop is a converted old sheep shed and the floor is very uneven. I don't know diddly squat about building but I don't think it has a damp proof course - if that makes any impact on what I want(?).

I'd like to have nice and flat 3m x 3m concrete slab in the middle where I normally do all my laying out work, currently on 8x4 sheets of OSB levelled up on pallets.

How thick should a concrete slab be in this sort of situation? I don't want to bolt tools down on it so it's sole function is to be a flat surface.

My workshop is owned by a country house estate and their builder who did the conversion works did try laying some sort of thin vinyl(?) epoxy(?) layer over the top to level it up, but that cracked and crumbled in days.

Any pointers would be appreciated. Cheers

 

[Shedendman]

Mark out your 3mx3m dig down 150mm/200mm you'll need to pack in a sub base of about 75mm-85mm hardcore broken bricks etc then top base on concrete,heres a very basic guide
http://www.diydoctor.org.uk/projects/shedbase.htm
Thats only going on the spec/use you've said
Sounds to me that so called builder put self levelling compound (latex) over dirt,in my book hes marked as a plonker

 

[cumbriasteve]

If it's simply for laying out onto then I would make a frame of 100mm x 5mm flat bar, peg it down to the floor and pour ready mix into it, by tamping down across the frame you will get a good flat raised area and the only downside would be having it as a trip hazard.

The steel frame will protect the edges and could be painted to highlight it.

 

[slim_boy_fat]

The steel frame will protect the edges and could be painted to highlight it.

Or some of this stuff? http://www.ebay.co.uk/itm/PVC-Hazar...sive-Floor-Warehouse-50mm-x-33m-/161059774507

 

[Shedendman]

If it's simply for laying out onto then I would make a frame of 100mm x 5mm flat bar, peg it down to the floor and pour ready mix into it, by tamping down across the frame you will get a good flat raised area and the only downside would be having it as a trip hazard.

The steel frame will protect the edges and could be painted to highlight it.

That will crack like a cheap biscuit slab if not re-enforced(mesh) or a bit of a sub base for it to go on IMHO
I'd go level to the floor as much as poss,knock up a simple wooden frame from 6x1 mark off your 100mm from the bottom then level it out to that.

 

[Wendelspanswick]

If your existing floor is solid but just uneven the cheapest option would be a 50mm screed laid in a temorary frame till it's set, remove the frame then hand trowel a fillet screed against the edges to form a ramp all the way round.

 

[Wendelspanswick]

That will crack like a cheap biscuit slab if not re-enforced(mesh) or a bit of a sub base for it to go on IMHO
I'd go level to the floor as much as poss,knock up a simple wooden frame from 6x1 mark off your 100mm from the bottom then level it out to that.

He said his floor is uneven, he hasn't said it's cracked or loose, my old workshop had an uneven floor but it was 150mm concrete hand laid and not levelled off properly.

 

[Shedendman]

True,but i was only going on the fact its an old sheep shed and what the plonker did before so only assuming its compacted dirt

 

[addjunkie]

Digging out old concrete floors from sheep sheds is hard work, all depends on the shed what the base is. i have 3 stone barns, one has a stone cobble floor, i will happily concrete over when I do it up, no point in digging up stone to replace it with stone. The middle one is concrete, but after sheep have ysed it, its hard to tell what the floor is. The third, after 5 years I still dont know what yhe floor is.

If you want a good level floor, go to whats solid. Lay a membrane and screed over, pumped in if you can afford it. If its not solid you need to make it solid with hardcore, then rebar or use fiber impregnated concrete.

The raised but in the middle will eventually annoy you, when you keep tripping over it

 

[Thrashsmith]

Thanks for the ideas. I'd definitely want it flush with the surrounding flooring, if for no other reason it'll be much easier to wheel trollies & pallet jacks over.

The existing floor is some form of concrete, but very soft in some areas. I'd say it's only 6 inches max thickness & is bound up with stones, I've definitely drilled all the way through it before. I've got benches, fly press, anvils etc bolted to it but some areas are compete rubbish.

 

[Ton-up]

If your floor is crack free and not moving, I would dig out all soft loose concrete and put a 10 mm or so layer of INDUSTRIAL self levelling epoxy screed over it. Something like this from Watco. It is expensive, but very good. We put it down 7 year ago in a timber saw shop with steel wheeled barrows and no damage to date!

http://www.watco.co.uk/watco-flowtop.html