If self-performing concrete is new to you, then you probably have some questions on getting started with the basics. Well, you came to the right place! We have answers.
To start with: Concrete is ordered by the cubic yard (CY, or sometimes just called “yards”). You need to measure the volume of each distinct concrete pour.
Before you start measuring, find your concrete specification for your item, email it to your concrete provider, and ask for a quote for $/CY delivered and mix design meeting this specification. Ballpark the concrete yardage for this quote.
Here’s an example of this: I’m pouring a concrete slab of 5,000 PSI. I’ll call it 100 CY, and I’ll email it to Cemex for a quote. They tell me it’s $150/CY and mix number 1457382. I give this to my GC/owner for approval.
Now – it’s time to measure that concrete!
Whatever you’re pouring (a sidewalk, a slab, a footing, a retaining wall, etc.), measure the length, width, and height/depth of the object in feet.
Example: I’m building a new home that’s built on roughly rectangular slab. The slab measures 100’x50’ and will be 4” deep.
If your floor is an imperfectly-shaped slab, break up the slab pour into multiple rectangular areas.
Multiply length (ft) by width (ft) by depth (ft) to get a volume in cubic feet (CF). Using the same measurements as our example in Step 1, this looks like:
100 ‘ x 50’ x (4/12)‘ = 1667 CF
Convert CF to CY. There are 27 cubic feet in 1 cubic yard, so divide your answer by 27.
1667 CF / 27 = 61.7 CY
Determine how many total yards to order, along with how many trucks you’ll need delivered.
Concrete trucks typically come in two sizes: a 9 CY truck (most common), and a 11 CY slider truck (longer footprint, less common for residential work, more common for high volume mat slab pours or roadwork pours). To avoid “short load” fees, you must order full trucks, then order one “short load” as your final truck. Typically 1-2 CY of waste is acceptable for pours over 50 CY.
61.7 CY is needed
9 CY x 7 trucks = 63 CY, meaning 1.3 CY of approximate waste
Schedule your concrete pour four weeks in advance to secure concrete. To wrap up our example, you’ll need to order 63 CY of your mix.