Can you order concrete by the cubic yard? Yes, you absolutely can, and this guide will walk you through every step. Ordering concrete might seem a bit daunting at first, especially if you’re new to construction projects. But with a little preparation and knowledge, you’ll be able to confidently place your order and ensure your project gets the right amount of the right material. This concrete ordering guide is designed to make the process as clear and straightforward as possible, from calculating your needs to scheduling your concrete delivery.
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Figuring Out Your Concrete Needs: The First Step
Before you even pick up the phone, the most crucial step is to accurately determine how much concrete you need. This is where concrete calculation comes into play. Ordering too little can lead to project delays and extra costs for a second delivery. Ordering too much means you’ve paid for material you won’t use, and dealing with leftover concrete can be messy. The key is to calculate your concrete quantity with precision.
Calculating Cubic Yardage for Your Project
The standard unit for ordering concrete is the cubic yard. So, how do you figure out your cubic yardage? It’s a simple geometric calculation based on the dimensions of your project area. You’ll need to measure the length, width, and depth (or thickness) of the space you intend to fill with concrete.
The basic formula is:
Volume = Length × Width × Depth
However, remember that these measurements need to be in feet before you can convert them to cubic yards.
Steps for Accurate Cubic Yardage Calculation:
- Measure the Area: Measure the length and width of the area you need to cover in feet. For example, if you’re pouring a patio that is 10 feet long and 12 feet wide, your measurements are 10 ft and 12 ft.
- Determine the Depth: Measure the desired depth of the concrete in inches. For most standard projects like patios or walkways, a thickness of 4 inches is common. For driveways, 5 or 6 inches might be better.
- Convert Depth to Feet: Since your length and width are in feet, you need to convert your depth measurement from inches to feet. To do this, divide the number of inches by 12 (because there are 12 inches in a foot).
- Example: If your depth is 4 inches, you divide 4 by 12, which equals 0.33 feet.
- Calculate the Volume in Cubic Feet: Now, multiply your length, width, and depth (in feet) together.
- Example: For a 10 ft x 12 ft area with a 4-inch depth (0.33 ft):
10 ft × 12 ft × 0.33 ft = 39.6 cubic feet.
- Example: For a 10 ft x 12 ft area with a 4-inch depth (0.33 ft):
- Convert Cubic Feet to Cubic Yards: One cubic yard is equal to 27 cubic feet (3 ft × 3 ft × 3 ft = 27 cu ft). So, to convert your cubic feet measurement to cubic yards, divide the result by 27.
- Example: 39.6 cubic feet / 27 = 1.47 cubic yards.
Accounting for Irregular Shapes
Many projects, like ordering concrete for a driveway, involve more than just simple rectangles. You might have curves, slopes, or irregularly shaped areas.
- Breaking Down Complex Shapes: For complex shapes, break them down into simpler geometric forms (rectangles, squares, circles, triangles). Calculate the volume for each section and then add them all together.
- Circular Slabs: If you have a circular area, the formula for the area of a circle is πr² (where π is approximately 3.14 and r is the radius). Multiply this area by the depth (in feet) and then divide by 27 to get cubic yards.
- Example: A circular patio with a 5-foot radius and 4-inch (0.33 ft) depth.
Area = 3.14 × (5 ft)² = 3.14 × 25 sq ft = 78.5 sq ft.
Volume = 78.5 sq ft × 0.33 ft = 25.9 cubic feet.
Cubic Yards = 25.9 cubic feet / 27 = 0.96 cubic yards.
- Example: A circular patio with a 5-foot radius and 4-inch (0.33 ft) depth.
Table: Common Depth Conversions to Feet
| Depth in Inches | Depth in Feet |
|---|---|
| 3 | 0.25 |
| 4 | 0.33 |
| 5 | 0.42 |
| 6 | 0.50 |
| 8 | 0.67 |
The Importance of the Waste Factor (Over-ordering)
It’s almost always recommended to add a little extra to your calculated concrete quantity. This is commonly referred to as a waste factor or over-ordering. Why?
- Uneven Subgrade: The ground beneath your pour might not be perfectly level. Some areas might naturally end up with a little more depth than planned, while others might be slightly less.
- Spillage: Some concrete is inevitably lost during the pouring and spreading process.
- Slump: The amount of water added to the concrete mix (its “slump”) can affect its volume slightly.
- Settling: Concrete can settle a bit as it’s worked.
A good rule of thumb is to add 5% to 10% extra to your total cubic yardage.
- Example (Continuing previous example): If your calculated need is 1.47 cubic yards, adding 10% would be:
1.47 cubic yards × 1.10 = 1.62 cubic yards.
In this case, you would likely round up to 1.75 cubic yards or even 2 cubic yards, depending on the supplier’s ordering increments. It’s better to have a little extra than to run short.
Choosing the Right Concrete Mix Design
The amount of concrete isn’t the only thing you need to get right; the concrete mix design is equally critical. This refers to the proportions of cement, aggregate (sand and gravel), water, and admixtures. The mix design determines the strength, durability, and workability of the concrete.
What to Consider for Your Mix Design:
- Project Type:
- Driveways and Patios: Typically require a mix with a compressive strength of 3,000 to 4,000 psi (pounds per square inch). A mix with larger aggregate might be suitable for driveways to add durability.
- Slabs (Foundations, Garage Floors): Often need a strength of 2,500 to 3,500 psi.
- Sidewalks: Might use a 3,000 psi mix.
- Decorative Concrete (Stamped, Colored): May require specialized mixes and admixtures.
- Environmental Conditions:
- Freeze-Thaw Cycles: In colder climates, you’ll need air-entrained concrete to improve its resistance to freezing and thawing. This involves adding special admixtures.
- Exposure to Water/De-icing Salts: Similar to freeze-thaw, these conditions can degrade concrete, so a stronger, more durable mix is often needed.
- Workability (Slump): The slump is a measure of how much the concrete will sag or “slump” under its own weight when formed into a cone. A higher slump means more fluid concrete, which is easier to pour and spread, especially for intricate shapes or areas with lots of rebar. A lower slump means stiffer concrete, which is stronger but harder to work with. Most common mixes have a slump between 4 and 6 inches.
How to Specify Your Mix Design:
When you order, you’ll usually specify the strength (psi) and slump. You can also mention the intended use and environmental conditions. A good ready-mix concrete supplier will have standard mixes available and can advise you on the best option for your project. Don’t hesitate to ask questions about their recommendations.
Placing Your Order: What Information to Provide
Once you’ve done your calculations and have a good idea of the mix design you need, it’s time to contact a ready-mix concrete supplier. Here’s the information you’ll need to have ready:
Essential Details for Your Order:
- Your Name and Contact Information: So they can confirm your order and delivery details.
- Project Address: Where the concrete needs to be delivered.
- Date and Time of Delivery: Be specific! Specify a date and a time window. Be aware that concrete delivery schedules can be tight, and delays can happen. It’s often good to schedule for a little earlier in the day if possible.
- Quantity of Concrete: Your calculated cubic yardage, plus the waste factor. Be clear about whether you’re ordering 2.0 cubic yards, 2.5 cubic yards, etc. Most suppliers deal in quarter-yard increments or half-yard increments.
- Concrete Mix Design:
- Strength (psi): e.g., 3,000 psi, 4,000 psi.
- Slump: e.g., 4-inch slump, 5-inch slump.
- Aggregate Size: For some projects, the size of the aggregate (gravel) matters. For example, 3/4-inch aggregate is common for slabs.
- Special Admixtures: Air-entrainment, accelerators, retarders, colorants, etc.
- Pouring Location: Provide details about the accessibility of the pour site. Can the truck get close? Are there any obstacles? This is crucial for efficient concrete delivery.
- Access for the Truck:
- Can a large, heavy ready-mix truck drive to the exact pour location?
- What is the width and height clearance?
- Are there any steep inclines or soft ground conditions?
- Is there a place for the truck to turn around?
Considerations for Delivery Access:
This is a point that often gets overlooked, leading to problems on delivery day.
- Truck Size: Ready-mix trucks are large and heavy. They need stable ground and adequate turning radius. A standard truck can be up to 26 feet long and weigh over 60,000 pounds when loaded.
- Getting Close: The closer the truck can get to the pour site, the less you’ll need to worry about using chutes, wheelbarrows, or concrete pumps.
- Chutes: Most trucks have chutes that can extend 10-12 feet. If your pour is further than that, you’ll need to plan for other methods.
- Wheelbarrows: If you’re using wheelbarrows, ensure you have enough people to move the concrete quickly before it starts to set.
- Concrete Pumps: For large pours or difficult-to-access areas, a concrete pump might be necessary. This will be an additional cost, but it can be essential for a successful pour. You’ll need to arrange this in advance with the concrete supplier or a separate pumping company.
The Concrete Delivery Day
You’ve ordered, you’ve calculated, and now it’s delivery day! Proper preparation on your end will make the process much smoother.
Pre-Pour Day Preparations:
- Prepare the Site: Ensure the area to be poured is excavated to the correct depth, leveled, and compacted.
- Install Forms: Set up and secure your forms so they are ready for the concrete. Make sure they are level and plumb (straight up and down).
- Reinforcement: If your project requires rebar or wire mesh for reinforcement, install it before the concrete arrives.
- Vapor Barrier (for Slabs): If you’re pouring a slab for an indoor space (like a garage or basement), install a vapor barrier (usually plastic sheeting) on the prepared subgrade.
- Water Source: Have a water source available in case slight adjustments are needed to the mix, though this should be done sparingly and with the supplier’s guidance.
- Tools and Labor: Gather all necessary tools: shovels, rakes, screeds, bull floats, edgers, trowels, and, of course, your team of helpers.
During the Pour:
- Be Present: Always be on-site when the concrete is delivered.
- Communicate with the Driver: Confirm the order details with the truck driver and guide them to the exact pour location.
- Monitor the Pour: Watch the concrete as it’s being placed. Ensure it’s filling the forms evenly.
- Work the Concrete: Use shovels or rakes to move the concrete into the forms and spread it out. Vibrate the concrete if necessary to remove air pockets, especially if using reinforcement.
- Screeding: Use a screed board (a straight edge) to level the surface of the concrete, knocking off any high spots.
- Floating: After screeding, use a bull float to smooth the surface and embed the larger aggregate just below the surface.
- Edging and Jointing: Once the concrete has stiffened slightly, use an edger around the perimeter and a groover to cut control joints. These joints help control where the concrete cracks as it cures.
Common Mistakes to Avoid
Even with careful planning, mistakes can happen. Being aware of common pitfalls can help you avoid them.
What to Watch Out For:
- Inaccurate Calculations: The most common mistake is miscalculating the concrete quantity. Always double-check your math and add that waste factor!
- Underestimating Delivery Needs: Not thinking through truck access can cause major headaches.
- Not Considering the Mix Design: Using the wrong strength or slump for your project can lead to premature failure or difficult installation.
- Adding Too Much Water: Resist the temptation to add extra water to make the concrete easier to work. This drastically reduces its strength and durability.
- Poor Site Preparation: A sloppy subgrade and poorly secured forms will result in a poor-quality finished product.
- Not Having Enough Help: Concrete sets faster than you think. You need enough hands to spread, level, and finish it in a timely manner.
- Not Cutting Control Joints: If you don’t cut control joints, the concrete will crack in random places as it shrinks during curing.
Frequently Asked Questions (FAQ)
Q: What is a cubic yard of concrete?
A: A cubic yard of concrete is a volume measurement equivalent to a cube that is 3 feet long, 3 feet wide, and 3 feet high. It is equal to 27 cubic feet.
Q: Can I order less than a cubic yard of concrete?
A: Most ready-mix concrete suppliers have a minimum order quantity, which is often 1 cubic yard. Some might offer smaller amounts, but it’s less common and can be more expensive per yard. It’s best to check with your local supplier.
Q: What happens if I order too much concrete?
A: If you order too much and it’s still in the truck, the supplier might be able to take back a small amount, but there will likely be a disposal fee. If it’s already been poured, you’ll need to dispose of the excess yourself, which can be challenging. This is why accurate concrete calculation and adding a reasonable waste factor are so important.
Q: How long does concrete take to set?
A: Concrete begins to set within a few hours. It typically gains significant strength within 24-48 hours. However, it continues to cure and gain strength for weeks or even months. The exact setting time depends on the mix design, temperature, and humidity.
Q: Can I pour concrete in cold weather?
A: Pouring concrete in cold weather requires special precautions. You may need a heated mix, accelerators, and protection for the fresh concrete to prevent it from freezing. Consult with your ready-mix supplier about cold-weather mixes.
Q: What is slump in concrete?
A: Slump is a measure of the workability of fresh concrete. It indicates how easily the concrete can be molded or deformed. A higher slump means more fluid concrete, while a lower slump means stiffer concrete.
By following this concrete ordering guide, you can approach your next project with confidence. Proper estimation of concrete, careful consideration of your concrete mix design, and clear communication with your supplier will ensure a successful concrete delivery and a long-lasting finished product.