An Ohio homeowner used the prices of lumber in the last year to decide the cost of a two-car unit garage. When the framing was complete, the job had cost over $6,400. The design had not changed. The cost of Division 06 lumber and sheathing had simply increased between the estimate and construction. This is one of the main risks garage estimating needs to account for. 

SMA Estimating LLC’s garage estimating services use current material prices and allow for price changes instead of relying on one flat rate. Every garage takeoff is checked against current material price indexes before it is sent to the client. The estimate was not based on costs of the prior project or costs of the last several months because those costs are no longer current.

What Is The Average Cost To Build A Garage?

Most people expect a 2-car detached garage to cost less than it actually does. Constructing a detached garage costs about $14,400-$33,600 on average. The cost can be anywhere between $40 and $70 per sq. ft for a garage, depending on the size of the garage and the quality of the finish (Angi detached garage cost guide).

Garage construction costs increase as the number of cars and the size of the garage increase:

Why Do Garage Estimates Miss The Mark So Often?

Most missed estimates are not caused by math errors. They happen because important costs are left out. A garage cost estimating sheet, which includes slabs, framing, and roofing, may neglect to mention expenses that can add up to a significant amount:

• Depending on the location, the cost of permits and inspection can be different.

• Site preparation such as excavation and grading may be necessary.

• The garage door can be expensive, up to $300 to $2,400, depending on the size and insulation.

How Much Does Lumber Price Volatility Actually Move A Project Cost?

Material prices can change faster than most homeowners expect. Softwood lumber producer prices increased from an index value of 250.2 in December 2025 to 270.3 in February 2026, an increase of about 8% in two months, according to Bureau of Labor Statistics data via FRED. On a framing package costing several thousand dollars, a price increase like this can reduce a contractor's margin if the estimate was prepared weeks earlier.

Garage Cost Breakdown by Category

What Should A Realistic Project Cost Estimate Include?

A complete estimate should answer not only what would be the garage project cost, but also what could still affect that cost. That means allowing for material price change on lumber intensive items, verifying current permit and inspection fees with your local jurisdiction, and pricing doors and windows by their specs instead of by a rough allowance.

Conclusion

Garage estimating is more than applying a standard rate to the square footage. It means checking each cost category, keeping current market prices in mind, and allowing for changes in materials such as lumber. SMA Estimating LLC prepares garage estimates with these factors in mind, helping contractors avoid gaps between the original quote and the final project cost.