The Brew Cabin

I will be putting a patio down and was wondering what the calculations would be for measuring how much builders sand and cement I would need to dry grout an area of about 33 square metres using 600 x 600 mm slabs.

Thanks in advance

Hi Alan,

the calculation, assuming 12mm joints is.....


nr of flags per m2 X 1/2 flag perimeter X joint depth X joint width

....which gives.....

1200mm x 50mm x 12mm = 0.002m3 per m2

....so for 33m2 you need 0.067m3 of mix.


Using a density of approx 1.9 t/m3, that comes to 125Kg, which, at 5:1 is 21 kg of cement and 104kg of sand.

If you buy a 25Kg of cement and 3 x40kg or 3 x 50Kg bags of sand, that'll allow for wastage. You can safely use a 6:1 ratio for patios, so 3 bags of sand plus a 25kg bag of cement (what we call a 'half-bag') :)

If that doesn't work out, let me know!

Thanks Tony,

I shall now start the patio over the Easter weekend, and will let you know if it doesn't work out !