Concrete Decisions Concrete Decisions
Before you can actually pour the concrete for your new concrete patio, you still need to figure out a couple of things – just how much concrete do you actually need for the job and, what is the best way to get all that concrete.
Estimating how much concrete you need
- First take careful measurements of your formed patio layout. These measurements are important because if they’re off by even 1/2 inch you could end up without enough concrete. This is also why you need to be sure your base is prepared well and the depth is the same all over. Here again, if it’s 4” deep in one place and 5” deep in another section, your estimate will be off and the patio slab itself will be prone to cracking and breaking.
- Once you’ve got your measurements, it becomes a question of using some basic math. Mixed concrete is sold by the cubic yard, usually just called a yard. This is equivalent to a space 3’ x 3’ x3’tall or 27 cubic feet.
- If your patio is 12 feet by 15 feet by 4 inches deep your concrete calculations would look like this:
- 12 x 15 x 4 = 720
- Converting to cubic feet 720/12 = 60
- Converting to cubic yards 60/27 = 2.23 cubic yards of concrete.
- Add 10% for waste and you will need 2.45 or 2.5 cubic yards for your new patio.
Where to get your concrete
- You have a few choices as to where to actually get the concrete for your patio. You can do it yourself either by purchasing the ingredients and mixing it yourself, or purchasing bags of Ready mix concrete at your home store. Or you can order concrete from a concrete supplier in your area.
- Ready mix concrete is normally sold in 60 or 80 pounds bags. A 60-pound bag makes about ½ cubic foot of concrete so for this project you would need about 120 bags of Readymix.
- You could also rent a cement mixer and order the individual concrete ingredients Portland cement, sand and gravel and add your own water to get your concrete. Although the ingredients of concrete are always the same, getting the right mix for a particular job is complicated. And perhaps best left to the pros. As well, for a project of this size actually mixing that amount of concrete is an enormous amount of work and it’s virtually impossible to pour your entire patio at one time.
- Probably the best way (although not likely the cheapest) way to get the concrete for your patio is to get it delivered by a concrete company in a barrel truck. Many concrete companies don’t like to deliver loads smaller than 1 yard, so in this case it isn’t a problem. However, as in any competitive business there are likely suppliers in your area that will either have special equipment or be willing to provide smaller quantities if you shop around.
- Another advantage of getting your concrete from a concrete supplier is you won’t need to go to the trouble of calculating how much you need. They will likely do the calculating job using the measurements you give them.