How much concrete do I need for 42X24 slab 4" deep?

Question

How much concrete do I need for 42X24 slab 4" deep?

Answer 1

One cubic yard covers 80 sq ft. @ 4" on flatwork.

24'x42'= 1008 sq ft

1008 / 80 = 12.6 cubic yards

This is the figure in a perfect world ie sub grade is perfect and yield correct from supplier.If it was on one of my jobs I would order 13.5 as the cost of a clean up load is very expensive.Another consideration is using reinforcement,fiber mesh,wire mesh,rebar.

A personal note: Since you asked this in DIY I would like to say these projects can run away with you.After all the old adage "it gets hard and cracks".Talk to your supplier before ordering,I strongly recommend the use of "Delvo",a concrete stabilizer.This very in expensive and will give you more time to work the mud.

Good Luck

Answer 2

42x24=1008 sq ft

1008/3=336 cu ft  Since the slab is 4" deep each sq ft is 1/3 cu ft so you divide by 3 to get cubic feet

336/27=12.444 cu yds  27 cu ft in 1 cu yd so since concrete is sold by the cubic yard you figure how many cubic yards you need.

I would order 13 yards of concrete.

With a slab that big make sure you have a good well tamped crusher run gravel base and re-bar or mesh and cut/strike breaks in it. Any 4" slab that large is going to crack so make sure it cracks where you want it to not where it wants to. Look at a sidewalk and you will see grooves cut across for it to break on instead of breaking where it wants.  

One other thing, if this is for a garage you will probably need a 4" down turned curb and a 4" upturned curb. Check your local building codes for that. That will add to your concrete.

Answer 3

If the 42x24 is in feet, you would need 12.44 cubic yards (yards) of concrete, ordering probably 14 yards.

If the 42x24 is also in inches, then you need .08 yard of concrete and should just buy a bag of ready mix at the hardware store.

Answer 4

You would need just under 13 cubic yards.

Here is a link to a calculator you can use for this type of work.

http://www.concretenetwork.com/concrete/...