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12 Mistakes I Made Building My Garage (So You Don’t Have To)

From a trench dug to the wrong size to a permit that faded in the sun, here are the lessons from my first garage build — and how to avoid every one of them.

In this guide

I built a 32×24 three-car garage with almost no construction experience, which means I learned most things the hard way. Here are the mistakes that cost me the most time, money or sweat — and what I’d do instead.

1. Not planning in block modules

I dug my trench for a perfect 32×24, but block foundations don’t come out to round numbers. I had to adjust later. Instead: plan the foundation in whole and half blocks so the outside edge lands at or just under your framing size. More here.

Leveling a block footer on the bottom of a trench was brutal, and drilling 144 blocks for rebar took ages. Instead: pour a concrete footer with rebar on chairs and build block on top. My footer story.

3. Buying the cheap drill first

A bargain hammer drill couldn’t handle hundreds of holes in block. Instead: buy or rent a real SDS rotary hammer on day one.

4. Running the drill too fast

I turned a couple of blocks to dust before I learned to drill at the slowest speed. Instead: go slow — let the tool work.

5. Not planning how to get the rebar in

At the end of each footer row, there was no room to slide the rebar in. Instead: plan the last few blocks and any extra digging before you set them.

6. Planning to fill the cores by hand

I was about to buy hundreds of bags of concrete. The inspector pointed out that would take weeks and create weak cold joints. Instead: order ready-mix — a conveyor or pump truck if access is tight. How the pour went.

7. Too few helpers on pour day

Concrete comes off the truck fast. Two of us plus a generous driver barely kept up. Instead: line up at least three or four people.

8. Ordering dirt from a big hauler

One truckload from a large company cost a fortune and barely made a dent. Instead: find a local operator with a dump truck. The dirt saga.

9. Taping the permit where the sun could reach it

The “sun-proof” permit pouch faded within a week. Instead: keep the permit card in a cheap mailbox on a post. Permit tips.

10. Not asking the inspector sooner

My inspector was the most helpful person on the whole project. Instead: call early with questions — before you pour, before you cover anything.

11. Leaving rebar uncapped

Vertical rebar at eye level is dangerous. I was lucky. Instead: buy rebar safety caps.

12. Underestimating the time

I started researching in 2006 and finished in 2009. Instead: plan realistically, protect each phase from the weather before you pause, and consider hiring the one-day jobs like roofing.

Key Takeaways

  • Most of my mistakes came from not planning a step before starting it.
  • Ask the inspector early — it’s free expertise.
  • Pay for the jobs a crew does in a day.

Written by a first-time builder.

I built a 32×24 three-car garage in the Colorado Rockies with almost no construction experience — my own labor, an engineer’s plans and a lot of trial and error. These guides share exactly what worked, what didn’t, and what I’d do differently. More about me →

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