Most garage-cost articles give you eight factors and treat them as equals, as though the door package matters as much as excavation.
It doesn’t. We price these jobs, so we know which factors move real money.
This is the order we use for the garage work we take on. You’ll find the dollar figures in the full Augusta cost ranges.
One item can add thirty thousand dollars while the rest add hundreds. Here’s the list in the order that matters.
1. Excavation, and it is not close
Site conditions are the largest variable on a Maine garage. Bigger than the roof, doors or bay count.
We price the entire building around the site conditions:
| Site conditions | Cost per square foot |
|---|---|
| Unfinished shell | $130 to $160 |
| Finished inside: insulation, drywall, trim, two coats of paint | $250 to $280 |
Consider what that range does to one building. A 24x24 garage covers 576 square feet.
The shell costs about $74,900 on a clean site. Put the same building on real ledge and it runs about $92,200.
Same drawings and materials. Same crew.
What’s beneath the topsoil accounts for the difference.
And conditions can change within one property. Two identical garages placed two hundred feet apart can differ by tens of thousands because one sits on loam while the other sits on rock.
That’s why we won’t price a garage from a phone call or satellite photo. We aren’t stalling.
The biggest figure in the quote is hidden from the road.
2. Size, in four-foot steps
Square footage multiplies the other costs, which makes size the second lever. The price doesn’t rise smoothly.
Frankly, this is the easiest money to save.
Building materials follow four-foot modules. Sheathing comes in 4x8 sheets.
Studs come in 8, 12 and 16-foot lengths. Dimensions divisible by four put sheet edges on framing and reduce waste.
Odd dimensions require the same material, plus the labor to cut it and handle the offcuts.
| Size | Square feet | Roughly |
|---|---|---|
| 22 x 22 | 484 | $77,400 |
| 24 x 24 | 576 | $74,900 |
| 26 x 26 | 676 | $108,200 |
| 28 x 28 | 784 | $101,900 |
A 24x24 costs about the same as a 22x22 but provides 92 additional square feet. A 28x28 is priced about like a 26x26, with 108 additional square feet.
If one of the two sizes you’re considering divides by four, choose it. The added room costs very little.
Homeowners regularly wish they had gone larger, and size can’t be corrected later.
3. Bay count
Each added bay requires more roofline and foundation. It also means additional siding, framing and at least one overhead door.
Unlike site conditions, this cost is your choice.
Based on the model above, for a normal site:
| Size | Typical dimensions | Range |
|---|---|---|
| 1-bay | 12x24 to 16x24 | $37,000 to $61,000 |
| 2-bay | 24x24 to 28x24 | $75,000 to $108,000 |
| 3-bay | 32x24 to 36x24 | $100,000 to $138,000 |
Depth is usually a better purchase than another bay. Twenty-four feet is the minimum for a truck or large SUV.
At twenty-eight feet, you gain walking room and space for a workbench. There’s also somewhere to put all the stuff that collects in a Maine garage.
4. Foundation type
A slab costs less than a frost wall. The frost wall makes the better building.
Any good concrete contractor will say the same.
The difference is smaller than many people expect. For a typical garage, a frost wall adds roughly 20 to 25 percent to the concrete portion, not the entire build.
On a standard garage, that’s about $6,000 to $12,000 depending on perimeter and depth.
A slab makes sense over shallow ledge. If rock appears at 30 inches, installing a deep frost wall means blasting.
A properly insulated slab on sound bedrock can work, provided it has thickened edges with clean gravel beneath it.
On frost-susceptible soil without those conditions, it’s a gamble. As Seth says, you’re rolling the dice on whether the slab cracks later.
5. The door package
Every overhead door costs money. Insulated doors cost more than standard ones.
People often get this backwards. Two single doors for a two-bay garage cost more than one wide double door of equal total width.
If money is tight and the appearance doesn’t matter to you, choose the double.
Don’t save on door height. Nine feet clears essentially every residential vehicle, even a truck fitted with a rack or plow frame.
The added cost is small. A short opening is permanent.
6. Attached or detached
Builders disagree over whether an attached or detached garage costs more. That disagreement is the honest answer.
One builder may price attached construction lower because it needs only three walls. Another may charge more because joining a garage to an existing house requires careful work.
In some cases, the prices are about equal.
Cost rarely settles the choice:
- Setbacks. If your lot will not allow a garage beside the house, that placement is dead no matter what you would prefer.
- Excavation. Slope, granite or ledge in the spot you want can make that spot expensive or impossible.
- How you attach. Tying into a wall is simpler and cheaper. Tying into an existing roofline, especially a hip or a slant on the gable side, is more complicated and costs more.
If you attach the garage, place a mudroom or entry between it and the house. Otherwise, the mud on your boots goes straight indoors.
7. Matching your existing siding
Matching the house exactly can cost more than using a standard package. The difference grows when the existing siding uses an unusual material or discontinued color.
Our own siding crews in Augusta hang the siding, leaving the match with one crew instead of two.
Sometimes a deliberately complementary finish looks better than a strained match. We’ll say so when matching the house costs more than it’s worth.
8. A loft, or living space above
A storage loft requires framing plus flooring and costs roughly $4,000 to $9,000. Finishing it as usable space costs more.
A full apartment above the garage belongs in a separate price band. It carries plumbing, HVAC, a kitchen and egress, along with full residential systems.
Garage math doesn’t apply.
Say so early. Designing the foundation and roof structure for an apartment from the start keeps the option open.
Build them lighter and that option is gone.
What barely matters: your town
People assume a project in Augusta costs more than the same job twenty miles away. Usually, the difference isn’t noticeable.
Mobilisation is the geographic cost that matters. The crew travels to the property every working day during a multi-week build, and equipment has to get there too.
From the nearest town to the farthest point in our service area, the total difference is 4.9 percent.
Compare five percent with a thirty-thousand-dollar excavation swing. If a builder charges much more because of your zip code, ask which site condition accounts for it.
The answer should involve soil or slope, access or ledge.
The trap when you compare quotes
A figure far below ours usually covers less work. It isn’t a better price.
For us, turnkey includes excavation and site work. It also covers the slab, framing, siding and windows, plus doors, roofing and electrical rough-in.
You can park inside and plug in.
It does not include a finished interior. No drywall or insulation.
No interior finish.
Bring that scope to every builder and ask what the quoted figure includes. Excavation and site work are the two omissions we see most often, even though they’re the costs most likely to change on a Maine lot.
Without them, the figure is an opening bid, not a quote.
Where to spend, and where not to
Cut here if you need to:
- Slab instead of frost wall, if the garage will never be heated or finished and the site supports it
- Fewer, wider doors on a two or three-bay
- Skip the loft, as long as the structure is designed to take one later
- Round to a size that divides by four
Do not cut here:
- Footing depth
- Framing lumber grade
- Door height
- Foundation work on anything that might be heated later
Maine’s freeze-thaw cycle exposes every shortcut in that second list. Usually after everyone has left.
FAQ
What is the biggest cost factor in building a garage? Excavation. It is the difference between $130 and $160 per square foot on the same building, which on a 24x24 shell is roughly $74,900 versus $92,200.
Why do two builders quote the same garage so differently? Usually scope, not price. Ask both what their number includes, specifically whether excavation and site work are in it. Then ask what site conditions they assumed.
Does a bigger garage cost proportionally more? Not in even steps. Dimensions divisible by four use material efficiently, so a 24x24 costs close to a 22x22 and a 28x28 costs close to a 26x26. Between two sizes, the one that divides by four is the better buy.
Is a prefab or modular garage cheaper? Roughly thirty percent cheaper, in our experience. What you give up is the ability to change anything. Having sold well over a hundred garages and garage plans, close to all of them involved a change somewhere in the process.
Does a steel building save money long term? Up front, often. On resale, Seth's read of this market is that a steel building tends to add about half what a comparable stick-built garage adds. That is his experience, not a published statistic, and it moves with whether there are comparable sales in your town.
How much should I expect to pay up front? No more than one third of the contract price. Maine law caps the initial down payment on a home construction contract at a third. If somebody asks for more, walk.
Can you give me a price over the phone? We can give you a range, and this article is most of it. We cannot give you a number, because the largest variable in your quote is under your topsoil.
Get a number for your actual lot
These figures are starting points. The final garage is priced for the property beneath it.
We will walk it with you. Ask us out to the lot and we will price what is actually there. Or read the Kennebec County ranges and the Lincoln County ranges.
Ranges on this page are estimates for Maine homeowners, not a quote. Site conditions, material prices and scope move them. Nothing here is a code ruling, and your Code Enforcement Officer has the final say on what your project requires.