My Concrete Poured 3 Yards Short and the Truck Had Already Left

The concrete truck pulled away at 11:47 AM on a Saturday. My brother-in-law and I stood in my driveway with rakes and floats, looking at 600 square feet of forms that should have been full of wet concrete.

They weren't full. Not even close.

The back third of my driveway was still bare dirt and gravel. Three cubic yards short. And the next available concrete truck? Monday morning, minimum $400 delivery charge, assuming they'd even do a small pour.

This is the story nobody tells you about DIY concrete work: the math is unforgiving, and mistakes aren't fixable with another trip to Home Depot.

The Math I Did (That Was Perfectly, Precisely Wrong)

My driveway needed replacing. L-shaped, 600 square feet total, 4 inches thick—standard residential spec. Concrete costs $140/cubic yard in my area.

The concrete supplier asked: "You sure about 7.5? Most driveways that size we do 9, maybe 10 with waste."

"Nah, I measured carefully. Did the math twice. 7.5 is perfect."

Reader, it was not perfect.

What I Didn't Account For (The List of Shame)

Mistake #1: The Ground Isn't Flat

My "4-inch thick" slab assumed the subgrade was perfectly level. It wasn't. Not even close.

The front of my driveway slopes toward the street for drainage. The excavator guy had graded it mostly flat, but there were dips and high spots—some areas needed 3.5 inches of concrete, others needed 5 inches.

Average depth: probably 4.3 inches, not 4.

Extra concrete needed: 0.3 inches × 600 sf ÷ 12 ÷ 27 = 0.56 yards

Mistake #2: Forms Aren't Perfect

I built the forms myself out of 2x4s staked every 3 feet. Standard DIY approach. What I didn't factor: 2x4s bow. Especially the cheaper ones from Home Depot.

Each bow outward means extra volume. A 20-foot board bowing out half an inch along its length adds maybe 2-3% extra volume to that section.

Across 120 feet of forms, that's real volume.

Extra concrete needed: ~0.4 yards

Mistake #3: The Truck Doesn't Empty Completely

Industrial concrete trucks hold a lot intheir drums. But that drum doesn't pour out completely clean. There's always 0.1-0.3 yards left coating the inside that you never get.

This is why contractors always order slight extra—they know the truck won't deliver exactly what's on the ticket.

Concrete lost to drum: ~0.2 yards

Mistake #4: Spillage and Waste

Concrete is heavy, wet, and hard to control with a rake. Some goes:

• Over the sides of forms (I didn't seal the bottom perfectly)
• Into cracks in the subgrade
• Onto tools, boots, wheelbarrows
• Just... everywhere except where you want it

Professional crews budget 5-10% waste. I budgeted zero.

Waste: ~0.5 yards

Mistake #5: The L-Shape Complexity

My driveway isn't a simple rectangle. It's L-shaped with a turn. That corner section? I measured the long and short sides and calculated a perfect right angle.

The corner isn't a perfect right angle. It's slightly trapezoidal because my property line is weird.

I undermeasured that section by about 15 square feet.

Extra concrete needed: ~0.2 yards

The Running Tally

The supplier was right. I should have ordered 9-10 yards. I was an arrogant idiot with a calculator.

What Happened Next (The Expensive Part)

11:47 AM: Truck leaves. I have 7.5 yards of concrete in forms designed for 9+ yards.

11:50 AM: Panic sets in. Concrete starts setting in about 90 minutes. Once it sets, you can't pour new concrete adjacent without a cold joint (which looks terrible and creates a weak point).

11:55 AM: I call the concrete supplier. "Can you send another truck with 2 yards?"

Response: "Minimum pour is 4 yards. We can deliver Monday for $400 setup fee plus $140/yard for a total of $960. But you'll have a cold joint."

12:05 PM: I call every other concrete supplier in town. Same thing—minimum 4-yard pours, nobody delivers Saturdays after noon.

Option 1: Emergency Top-Off (What I Did)

Home Depot sells 80-pound bags of concrete mix for $4.50 each. Each bag yields 0.6 cubic feet.

I needed 1.76 cubic yards = 47.5 cubic feet.

47.5 ÷ 0.6 = 79 bags minimum.

I bought 85 bags (they were out of stock, so I drove to three stores).

But here's the problem: 85 bags of concrete, mixed in batches in a rented mixer, poured abit at a time over 6 hours, DO NOT cure the same as a continuous pour from a truck.

The back section of my driveway has visible seams between batches. The color doesn't match perfectly. The finish texture is different.

It's functional. It's not pretty.

Option 2: What I Should Have Done

Accept the partial pour, let it cure, saw-cut off the bad section, and schedule a new 4-yard pour Monday for the back third.

Cost: $960 for the Monday pour + $200 for saw cutting and removal = $1,160. Plus I'd have a driveway that actually looked professional.

Instead, I saved $455.50 and got a driveway that screams "DIY mistake" to anyone who looks closely.

What That 2-Yard Shortage REALLY Cost Me

By trying to save $246 in concrete, I spent $705 fixing my mistake AND lowered my home's value.

And that's assuming my math on the fix was right. Spoiler: I was short again. Ended up making a 4th trip for 8 more bags.

Why Contractors ALWAYS Order Extra (And You Should Too)

After this disaster, I called three professional concrete contractors and asked how they estimate. Every one said the same thing:

"We calculate the perfect volume, then add 10-15% for waste, irregularities, and insurance."

One contractor showed me his estimating sheet:

For my driveway, this method would have yielded:

Base calculation: 7.4 yards
10% depth buffer: 8.14 yards
10% waste buffer: 8.95 yards
Round up: 9.0 yards

I would have had about half a yard left over, which I could have used for a small patio pad or told the driver to dump in my backyard for future use.

Instead, I had a crisis.

Other Hidden Costs of Concrete Work

The shortage was my biggest mistake, but it wasn't my first. Here's everything else I got wrong:

1. Timing Is Everything (And I Screwed It Up)

I scheduled for Saturday because I work during the week. But:

• Saturday delivery costs $75 extra
• Storm forecast Sunday—if I messed up and needed emergency fix, I'd be racing rain
• Concrete suppliers are slammed Saturdays, so I got the last truck at 11 AM—no rescue options

A Tuesday delivery would have been cheaper, less rushed, and if I ran short, I could call for emergency delivery same-day.

2. Rebar Placement Isn't Optional

I initially planned to skip rebar to save money. A contractor friend saw my forms and said: "You're going to regret that in about three years when your driveway cracks in half."

Emergency rebar purchase: $185 plus four hours installing it the night before pour.

He was right. Rebar is structural, and the $185 was the cheapest insurance I bought for this project.

3. Finishing Concrete Requires Actual Skill

I watched three YouTube videos on concrete finishing. I practiced with a float on a piece of plywood in my garage.

Real concrete setting while you're trying to smooth it? Completely different. It starts setting up faster than you expect, especially in warm weather.

My finish has swirl marks, some areas are rougher than others, and there's one spot where I left a visible trowel line.

A professional finisher would have cost $300 for my square footage. My finish looks like $300 of labor I should have paid.

What I Would Do Differently

1. Hire a Pro (Seriously)

I got three quotes before doing DIY:

• $3,200 (full tearout, forms, pour, finish)
• $2,900 (same)
• $2,650 (guy with sketchy reviews)

My total DIY cost:

• Concrete (initial order): $1,050
• Emergency concrete: $705
• Rebar: $185
• Forms (lumber): $240
• Tools (rented + purchased): $180
• Gravel base: $340
• Saturday delivery surcharge: $75

Total: $2,775

I "saved" $125 compared to the cheapest quote. But:

• My finish is amateur
• I have visible batched concrete patches
• I spent 40+ hours of labor
• I injured my back mixing emergency concrete
• I have no warranty

The professional quote at $2,900 included 5-year warranty and would have been finished in one day.

2. If You MUST DIY, Add 20% To All Calculations

Not 10%. Twenty percent. You're not a professional, you'll make measurement mistakes, your forms won't be perfect, and you need room for error.

Extra concrete costs $140/yard. Running short costs $700+ in emergency fixes.

3. Schedule Mid-Week, Early Morning

Wednesday at 7 AM delivery means:

• No weekend surcharges
• Full day to work if something goes wrong
• Suppliers can send rescue trucks if you run short
• Weather forecast is more reliable for 24-48 hours out

4. Rent Professional Tools

A real concrete vibrator costs $45/day rental. I tried to make do with a rake and tapping the forms.

Result: air pockets, weaker concrete, and visible surface bubbles.

The $45 would have been the smartest money I spent.

The Real Lesson (That Applies to Everything)

This isn't really a story about concrete. It's about the DIY hubris of thinking "I watched YouTube, I did the math, I can do this as well as a professional."

I can't. And that's okay.

Professionals in any trade have expertise you can't get from three videos and a weekend. They've made every mistake already—on someone else's property, while they were learning—and now they know how to avoid them.

My concrete shortage happened because:

• I didn't know what I didn't know (subgrade variations, form bow, etc.)
• I trusted my math over expert advice (the supplier told me to order more)
• I optimized for saving money instead of accepting contingency costs

The contractor who offered to do it for $2,900 would have ordered 9.5 yards, had 0.5 yards left over, and my driveway would look professional.

I did it myself, ordered 7.5 yards, ran out, spent $705 fixing my mistake, and have a driveway that looks DIY.

I didn't save money. I just changed what I spent it on: emergency fixes instead of professional labor.

Conclusion: Some Things Are Worth Hiring Out

Concrete work is:

• Permanent (you can't easily fix mistakes)
• Time-sensitive (once it starts setting, you're racing the clock)
• Physically demanding (even with help, I was destroyed)
• Skill-intensive (finishing smooth concrete is an art)
• Front-and-center visible (my driveway is the first thing people see)

All of those factors point to: hire a professional.

I learned that lesson for $2,775 plus 40 hours of labor plus a sore back plus a driveway that will haunt me until I sell this house.

Three years later, every time I pull into my driveway, I see the batched concrete patches in the back third. They're permanent reminders of the day I tried to save $125 and instead created a $700 problem.

If I could do it again, I'd call the contractor, pay the $2,900, and spend that weekend doing literally anything else.

Before you pour concrete: Use our concrete volume calculator and then add 15-20% for waste and contingency. Seriously. Order extra. Running short is exponentially more expensive than having half a yard left over.