Paving a garage? Or slab over slab.

dhutch · Posted: Thu Mar 29, 2012 2:23 pm

Ive got a tin double garage, about 5*4meter, on a concrete slab.

The issue is that becuase theres no join made between the tin and the slab surface water runs in and pools on the floor, which is pour in two section and not totally level, and from what ive seen, about 2-3inchs thick.

My first preposal was to lay a single coarse of bricks around the edge just inside the tin, just under the lower member of the frame to keep the surface water out and them pour two inchs of conrete over, tamp flat, and float smooth. Biggest sab ive done before was 4*5ft but i learn fast.

However obviously thats not very thick and im slightly worried it will breakup, its also i calculate about about £150 worth of concrete even if i mix it myself, inc £20 to hire a mixer. So another plan would be to lay slabs down, espically as I may be able to get enough to do the job for free, although it wouldnt give such a nice finish to work on, and i do spend a lot of time under my cars.

I was also thinking about where to get some damp proof ing in there, would you put a painted DPM down before pouring it, or if you did slabs, maybe a plastic sheet?

Daniel

cotswoldbuilders · Posted: Thu Mar 29, 2012 3:21 pm

Clean existing slab of, put on a couple of coats of synthapruff, scatter some sand over last coat.
Lay the slabs on full beds of mortar.

dhutch · Posted: Mon Apr 02, 2012 12:53 pm

cotswoldbuilders wrote:

Clean existing slab of, put on a couple of coats of synthapruff, scatter some sand over last coat.
Lay the slabs on full beds of mortar.

Fair enough. What the sand for?

Would you do this based on cost/speed or would you not expect a poured floor of that thickness to last?

If its going to break up if i poured ontop to level I would obviously rather do it with slabs, but if it would stay down I would prefer the finish given with a poured and floated off slab.

cotswoldbuilders · Posted: Mon Apr 02, 2012 3:29 pm

2 to 3 inches isnt really enough depth for laying concrete, it could lift/crack.
Youd need a minimum 100mm all over.

dhutch · Posted: Fri Apr 13, 2012 1:48 pm

cotswoldbuilders wrote:

2 to 3 inches isnt really enough depth for laying concrete, it could lift/crack.
Youd need a minimum 100mm all over.

I understand this is generally the case, and particularly as its a garage and I intent to use trolley jacks on it that does worry me a little. However as you cant get flags dead smooth anyway (they are effectively broken sections of concrete to start with) a poured stab does appeal.

Looking at cemex's ready mix site they offered fibre reinforced mixes. How much does this help and what if any other actions could be taken to increase the chance of a thin stab living?

Might seem as if I'm taking your advice and ignoring it, but I am still tempted to do with a thin poured capping slap, or even a thinner screed-type capping, even if it does somewhat crack in future. Partly because I would prefer a smooth painted finish to work on, and partly because I would rather not heft slabs about! Im also aware that in 10 years time I probably wont be at the house anymore, and that the garage is only a temporary steel construction anyway.