How much does a garage extension cost?
Ashburn, VA

How much does a garage extension cost?

Ashburn, VA

How much does a garage extension cost?

$60 – $120average cost to extend per square foot
$9,600 – $24,000average cost to add another bay / stall

Get free estimates for your project or view our cost guide below:

$60 – $120 average cost to extend per square foot

$9,600 – $24,000 average cost to add another bay / stall


Get free estimates for your project or view our cost guide below:
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Tara Farmer
Written by
Tara Farmer
Edited by
Kristen Cramer
Fact-checked by
Tom Grupa

Garage extension cost

A garage extension costs $60 to $120 per square foot, or $9,600 to $24,000 on average to add another vehicle bay to the existing structure. The cost to extend a garage with a second-story addition is $60,000 to $200,000+, depending on the room size and features.

Cost to expand a garage
Project Extension size (feet) Average cost
Extend 1-car garage to a 2-car garage 8' x 20' $9,600 – $19,200
Extend 2-car garage to a 3-car garage 10' x 20' $12,000 – $24,000
Expand 1-car garage to 3-car garage 20' x 20' $24,000 – $48,000
Add extra space to a garage 4' x 20' $4,800 – $9,600
Build room extension over garage 20' x 20' $60,000 – $200,000+

Cost breakdown to expand garage

Expanding a garage requires the same construction elements as building a new garage. However, expansion costs more per square foot than new construction due to the demolition involved and the challenges of working with the existing structure. The total cost depends on the size, features, and finish levels.

Garage expansion design and preparation costs

  • Design – A garage expansion typically requires an architect or engineer to assess the current structure and design a construction plan that works with the rest of the home. The architect will also ensure the expansion follows local building codes and zoning and setback requirements.

    • Architect fees are 10% to 20% of the construction cost for a garage extension or addition.

    • Hiring a structural engineer costs 1% to 5% of the construction cost. Architectural firms typically include a structural engineer's plan in their estimate.

  • Permits – Construction permits cost $500 to $2,000+. A garage expansion often requires multiple permits and inspections, depending on the project scope.

  • DemoDemolition costs $4 to $10 per square foot, depending on the location and amount of structure being torn down.

    • The cost to remove a wall is $500 to $2,000 for a non-load-bearing wall.

    • Removing a load-bearing wall costs $4,000 to $10,000.

Garage extension building costs

  • LaborGeneral contractors hourly rates are $50 to $150per hour. Many contractors charge a percentage fee of 10% to 20% of the total project cost instead.

  • Foundation – A concrete slab foundation costs $5 to $14 per square foot.

  • Framing – Garage framing costs $10 to $35 per linear foot for the framing alone, or $32 to $56 per linear foot for framing and drywall.

  • Electrical – Hiring an electrician costs $50 to $130 per hour, with a $100 to $200 service call fee that typically covers the first hour.

    • Electrical outlet installation costs $150 to $350 for labor and materials. Most states require at least one outlet per vehicle bay.

  • PlumbingPlumbing costs $4.50 per square foot to install rough-in plumbing pipes. The cost to install new plumbing fixtures is $300 to $800 per fixture.

  • Roofing

  • Siding – Garage siding costs $3 to $11+ per square foot, depending on the type.

  • Gutters – New gutter installation costs $5 to $15 per linear foot.

A garage extension to add a third car bay.
A garage extension to add a third car bay.

Garage expansion remodeling costs

Garage remodeling costs depend on the finish level of the space. Expanding an unfinished garage requires less labor and materials than a garage with insulation and drywall. Converting the garage to a full living space with windows, HVAC, and other features costs the most.

Garage extension vs. bump out cost

A garage extension costs $9,600 to $200,000+, depending on the size and whether extending up or out. A bump-out costs $5,000 to $30,000 on average. A bump-out extends a room's square footage by attaching a smaller room, requiring less damage to the existing structure.

  • The existing roof is typically left intact when adding a bump-out.

  • Consider a bump-out for extra workspace or when needing extra feet for a longer vehicle.

Cost to tear down and rebuild a garage

The cost to tear down and rebuild a garage may be less than extending the existing structure, depending on the existing garage's age and condition.

  • Tearing down a garage costs $2,500 to $11,000 on average.

  • A new garage costs $20,000 to $50,000+ for labor and materials, depending on the size, type, and features.

  • Building a prefab detached garage typically costs less than building an attached garage.

Cost to build an extension over garage

The average cost to build an extension over a garage is $60,000 to $200,000+, or $150 to $500 per square foot, depending on the size and features. Building up instead of out is often necessary for homes with limited lot space or strict zoning and setback requirements.

  • Building up often requires foundation and structural reinforcement, especially in older homes.

  • Building a finished space over a garage adds to the home's square footage and typically increases its value.

Is it worth extending a garage?

Extending a garage is worth it for some homeowners, depending on your location, budget, and existing home and lot. A garage extension may not increase your home's value as unfinished spaces do not count as home square footage. Still, the extra space may attract more potential buyers when selling the home.

Garage extension pros and cons
Pros Cons
  • Extra space (ideal for small home or large vehicles)
  • Guaranteed reserved parking
  • Vehicle protection (weather, theft)
  • May lower car insurance premiums due to reduced risk
  • Prohibitive cost
  • Lengthy design and construction process; often requires temporary relocation
  • Reduced yard size when extending out
  • May require the entire structure to be brought up to code

Getting estimates from garage builders

Before hiring a garage addition contractor to extend your garage, be sure to:

  • Get at least three estimates to compare.

  • Hire a company that is licensed, bonded, insured, and has been in business for 5+ years.

  • Look for a contractor or firm specializing in garage expansions or home additions.

  • Browse their reviews on HomeGuide and Google.

  • Ask for references with contact information.

  • Ask for a portfolio of past similar projects.

  • Check local regulations before extending or renovating the garage. Some cities require a specific amount of covered parking, and most areas have zoning and setback requirements.

  • Get a detailed contract and warranty in writing before the project starts.

  • Never pay in full before the project is complete. Follow a payment plan instead.

Questions to ask

  • What experience do you have with garage extensions?

  • Are you licensed, bonded, and insured?

  • What does the estimate include?

  • What additional costs could come up during the project?

  • How long will the project take?

  • Who will be doing the actual work?

  • Can I stay in my home during the project?

  • What permits do I need, and do you handle the permitting process?