There’s a simple way to calculate how much concrete it will take to make your patio, plus you will be able to make sure you are getting your money’s worth, if you decide to hire a contractor.
First, decide how big a patio you want. Since almost everybody needs to see something before they actually understand if that is what they want, you need to layout the size of the patio that you want to add on your lawn.
Contractors use spray paint to mark the outline of things they are going to build. This is called laying out a project. When you have spray painted the grass to show the size of your proposed patio, you will better understand exactly what your project will look like when you finish. Use a lot of paint so you can easily see the line.
Over the next couple of days, look at the outline to see if that is the size patio you want. What do you like about it? What don’t you like? What would you like to change?
Now is the time to make any changes that you want because it does not cost you anything to do it. Make the changes in a different color paint.
Now that you have decided on the size and shape of your patio, you can start to determine how much concrete you will need to do the job. This is called creating an estimate of the cost and is not as hard to do as it sounds.
Measure the outside of your patio and calculate the area. For instance, if your patio is 20′ x 25′ the area is the width x the length. So the area would be 500 SQ Feet. Now decide on how thick you want your patio to be. Most patios are 4″ thick. Now you need to convert the thickness of the patio into feet by dividing by 12. This would give you a thickness of 0.3333 feet.
Now its time to calculate the volume of the concrete that you will need to build your patio. Multiply the area in Sq. Feet (500 Sq Feet) x the thickness in feet (0.333 feet) and you get 166.66 Cubic feet.
All concrete is sold by the cubic yard. There are 27 cubic feet in 1 cubic yard of concrete, so in order to get the number of cubic yards you need just divide 166.66 by 27. The total number of cubic yards you need is 6.17.
Concrete costs vary from $70 per cubic yard to as high as $100 per cubic yard. (The concrete ready mix company and any contractor you talk to will refer to concrete in terms of yards instead of cubic yards, so don’t get confused.)
If you are going to do the patio yourself, you will need to tell the concrete ready mix company what you are going to be doing and when so they can give you the right mix of concrete. They will make the concrete to match the weather conditions and what you are going to be using it for.
I would not recommend that you attempt to make a pour this large unless you have some experience with concrete or have someone who can help you. 6 cubic yards is a lot of concrete to place and finish, especially if you are in your back yard and have to wheelbarrow it.
A reputable contractor will have a crew of 4-6 people to place a project of this size, so don’t think for a moment that you can do it with your buddies and someone who has seen concrete poured before. If you do decide to save a little money by doing it yourself, you might just have 12,000 pounds of concrete that you need do break up and haul away. (Each yard of concrete weighs around 3,500 lbs.)
You should get 3 prices from contractors in your area because prices vary from area to area. Choose the price in the middle so you know you are getting a reasonable price from a solid contractor.