[noshed]

I have to build a concrete slab 10'x8'2", 3-4" thick. How do I calculate how many bags of cement, gravel whatever to buy. (It's for the base for our famed allotment trading hut, which is now becoming a reality).

[Sally A]

think I googled for the concretecalculator

try this one


http://www.practicaldiy.com/general_building/concrete_calculators/concrete_calculator_2_m.php#paving

[Ruth Cross]

As a quantity surveyor this is my dream question, sad I know;
 you'll need total of 0.66m3 concrete (for slab 3.5inches thick), the amount of bags of material you will need depends on the mix you want; coarse, fine etc.

I'm sure the builders merchant or the info on the bag will tell you how many you need to make up the quant with the mix you require Hope that helps

[Sally A]

Ruth, it sort of shows you've been waiting since the 5th Oct 2007 for that one to come up

[Ruth Cross]

OHHH YESSSSSSSSSS    

[David.]

As a retired Quantity Surveyor, the above estimate is correct if the concrete is being spread on a dpm or sand/etc. fully blinded hardcore base, but more would be required if poured onto an open hardcore base.

I always used the guides in the front of commercial pricing handbooks , such as 'Spons' & 'Laxtons' from the office library, rather than info. from builders merchants.

[poultrygeist]

think I googled for the concretecalculator

try this one


http://www.practicaldiy.com/general_building/concrete_calculators/concrete_calculator_2_m.php#paving

I used this site for material calcs when I laid some strip foundations recently and it was pretty accurate. I've got 2 bags of ballast left over.
Best of luck with the slab.
Rob

[noshed]

Thanks chaps, much appreciated

[noshed]

I think my head has just exploded. The shed co reckon a base 305x247cm, say 10cm deep = 753350cm3 = .75m3?
My decimal points may have gone awry.

[noshed]

This seems to need 8  50kg bags of cement and a cubic meter of ballast - any idea how much this would cost (very roughly). Sorry about this I have to speak to some old Italians tomorrow.

[poultrygeist]

Using Wickes prices it's about £3/bag for a bulk order of 25kg bags.

Might get a better deal delivered from a builders merchant.

Jumbo bag of ballast which is, I think, about 700 or 800kgs about £35-£40 delivered.

Might be worth hiring a small mixer for the day/weekend.

Speeds the job up no end.

Best of luck.
Rob

[noshed]

Excellent, thanks a lot

[Tinbasher]

I think my head has just exploded. The shed co reckon a base 305x247cm, say 10cm deep = 753350cm3 = .75m3?
My decimal points may have gone awry.

Ten foot is more or less 3 metres (3050mm more precisely) and 8 foot is more or less 2.5 metres, so that's 7.5 metres squared.  Four inches is 100mm (ie a tenth of a metre) so the answer is 7.5 times 1/10 = 0.75 cubic metres.

[noshed]

I am a mathematical genius after all. thanks

[noshed]

It has all gone well - £66! And a lovely flat thingy