How Much Does a Garage Conversion Cost?

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If you're looking for extra living space for your family or extra income from an ADU (accessory dwelling unit) or an Airbnb rental, a garage conversion can be an economical alternative to a home addition, although it doesn't always make financial sense to do it. For example, in largely populated urban areas, a private garage can actually be worth way more than a dwelling unit (garages can be valued as much as $400,000 in cities like Boston).

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However, that's far from the rule; in most places, living space is more valuable than parking space, and by adding more living space to your home, a garage conversion is an investment that will increase the property value.

Thinking about doing a garage conversion? Here's how much it will cost you — and what's involved with construction.

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Garage Conversion Costs: What to Expect

A garage conversion costs as little as $25,000, but as much as $80,000 to $120,000.

What Is the Return on Investment?

The return on investment for a garage conversion is about 10 to 20 percent of the home's value. So, is a garage conversion investment worth it? That depends on many things, including:

  • the condition of the existing garage
  • the size of your garage
  • the scope of the conversion
  • the choice of materials
  • local labor costs

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If you just want to convert an attached garage to a bedroom, you might be able to do it for as little as $8,000 to $15,000 assuming the garage is already in good condition and you have enough handy skills to DIY some of the work. The cost to have a contractor complete a full-on conversion into a dwelling unit complete with kitchen and bathroom — particularly for a detached garage — could range from $25,000 to $80,000, and in high-market areas like urban California, it could be as high as $120,000 or more if you use top-quality materials.

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Considering the average ROI for a garage conversion is about 10 to 20 percent of the home's value, it's a no-brainer for homes in the million-dollar price bracket no matter what the use, but not necessarily so for homes worth half of that. It's true that money isn't always the primary consideration; homeowners may simply need more living space for themselves or members of their extended family. These days, however, with living space becoming increasingly scarce, the fact that an additional dwelling can generate income via short-term rental income or from a long-term tenant is a powerful motivator. Future income aside, the main concern for most homeowners is the upfront project cost and how to get the most for the least amount of money.

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Garage Conversion Cost Breakdown

To help with the planning, here's a breakdown of the various stages of the conversion process and the typical costs of each:

Permits

Item

Average Cost

Permit

$600 – $1,500

Hiring an architect (optional)

$2,000 – $4,000

You need a building permit for a garage conversion (assuming it's allowed in your community), and this isn't something you should skip. If you go ahead and build without a permit, you could get red-tagged and lose the use of the new property or find your home's value reduced or your home is unsellable. Real estate lenders tend to decline loans to unpermitted properties, especially those that violate local zoning ordinances. The cost of the permit depends on where you live and the scope of the conversion and is usually between $600 and $1,500.

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You need to draw up a floor plan to get a permit, and if you're adding electrical and plumbing fixtures, it's strongly recommended to hire a pro to do that. If you hire a general contractor for the entire project, the contractor will do the plan as part of the job, but if you're acting as your own contractor, you might hire an architect, who will likely charge between $2,000 and $4,000.

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Demolition

Item

Average Cost

Demolition

$720 – $2,520

An often-overlooked part of a garage conversion, demolition is a project in its own right. You typically need to:

  • Remove all the drywall so you can insulate the walls
  • Remove unwanted doors and windows, including the garage door, the door tracks, and the door opener
  • Remove built-in cabinets, shelves, and workbenches

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You don't necessarily have to reduce the space to nothing but open stud walls, but it helps, particularly if you're going to install new wiring and plumbing pipes. You can do the demolition yourself, but it's safer to hire trained pros, who typically charge between $2 and $7 per square foot, or from $720 to $2,520 for a 3,600-square-foot garage.

Framing, Doors, and Windows

Item

Average Cost

Framing

$700 – $1,600 for every 100 sq. ft. of new wall and ceiling area

Exterior doors

$700 – $2,000 per door

Interior doors

$400 – $1,500 per door

Windows

$400 – $2,000 per window

Once you've gutted the garage and you're ready to build, you'll likely need to do the following:

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  • Frame any new partition walls you plan to add for a bathroom, private bedroom, or kitchen space
  • Frame in the garage door opening and install any new doors or windows you want to add to the room
  • Install an entry door in the space that was occupied by the garage door
  • Add new ceiling joists for insulation and drywall (since many garages have high ceilings or no ceiling — just the underside of the roof — that leak air)
  • Add new doors and windows

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Framing can be estimated by square footage, with the average cost for labor and materials being between $7 and $16 per square foot, or from $700 to $1,600 for every 100 square feet of new wall and ceiling area. Framing materials — studs and wall plates — aren't very expensive, costing between $100 and $200 per 100 square feet, so this is where you can save big time by doing the work yourself as long as you don't modify the existing structure in a way that violates building codes. If you aren't sure, check with a contractor before you do anything.

As for the cost of adding doors and windows: Each window can cost from $400 to $2,000 depending on size, quality, and material, and a new exterior door costs around $700 to $2,000 depending on whether it's a conventional swinging, security, or sliding patio door. If you plan on installing interior standard or pocket doors, plan on spending from $400 to $1,500 for each one, not including installation. You'll save if you can do the installation yourself.

Plumbing and Electrical Rough-In

Item

Average Cost

Hiring an electrician

$3,000 – $5,000

Hiring a plumber

$3,000 – $5,000

Plan on extensive electrical and plumbing work if you're building an ADU or granny flat because you'll need to do the following:

  • Upgrade electrical circuitry (and possibly a new subpanel and/or upgraded utility service)
  • Add new water and waste lines for the bathroom and kitchen
  • Install a sewage line, which means you might have to break into the floor to make a trench (and depending on where you hook up the sewer, you'll probably also have to do some digging outside)

Count on paying an electrician from $3,000 to $5,000 (depending on whether you need a new subpanel) and probably about the same amount for the plumber. You may also need to hire someone to do any digging and concrete work that's required, and that costs extra.

Tip

If you're converting an attached garage to a bedroom, living room, or playroom, you won't have to do any plumbing, and the electrical work may be limited to adding a few light fixtures and receptacles to existing circuitry. If you can run new wires through the uncovered walls yourself without help, you might not need to pay an electrician, but you should hire one to check your work for possible code violations.

Siding, Insulation, and Drywall

Item

Average Cost

Siding

$500

Insulation

$1 – $2/sq. ft.

Drywall

$2.50 – $5/sq. ft.

With the walls uncovered and all the pipes and wires in place, you're almost ready to insulate, but first you have to:

  • Install siding on the outside of the wall you framed to cover the garage door opening
  • Insulate the entire structure, as needed
  • Hang and finish the drywall

The materials for siding, including house wrap and siding material, shouldn't cost more than a few hundred dollars, and labor should cost about the same. A total of $500 is a fair estimate, but it depends on what siding you choose.

Insulation you could easily do yourself, and you'll need R13 to R15 batt insulation for the walls, which costs about $1 per square foot, and R38 to R60 for the ceiling (depending on the climate), which costs about $2 per square foot. If you don't want to get itchy doing the work yourself, you'll need to pay about $300 to $500 for labor.

As for installing the drywall, the job involves hanging it, taping it, and applying three coats of joint compound (aka mud) plus any wall texture you want. Material costs for an 8 x 10-foot wall are around $200, or about $2.50 per square foot. If you don't install it yourself, expect to pay around $2.50 per square foot for professional installation — about $5 per square foot total.

New Flooring

Item

Average Cost

Laminate flooring

$1 – $5/sq. ft.

Luxury vinyl tile flooring

$1 – $5/sq. ft.

Most people take the easy way out by covering the concrete garage floor with a laminate or luxury vinyl tile (LVT) floor covering, with LVT being the better choice for high-moisture conditions. Both cost from $1 to $5 per square foot and are easy to DIY because they are "floating" floors that do not need to be glued or nailed down to the concrete garage slab. Other popular floating floor options include cork, linoleum, and engineered hardwood.

Window and Door Trim, Baseboards, and Paint

Item

Average Cost

Door and window casings + baseboards

$415 – $1,250

Hiring professional painters

$1,800

Often overlooked in the planning phase, the trim and paint turn your garage conversion project into a finished living space. Depending on the size of the garage, the door and window casings and the baseboards will cost between $830 and $1,250 if you have it professionally installed and about half of that if you do it yourself. The national average cost to paint a room is around $1,800, and you can save a significant chunk of that by doing your own painting.

Heating and Cooling

Item

Average Cost

Tying into home's existing HVAC system

$450

Mini split heat pump heating/cooling

$2,000 – $4,000

The most economical way to heat an attached garage is probably to install heating ducts that tie into the home's HVAC system, and the cost varies with the configuration of the system. This would normally be a low-end duct installation that would cost about $450 and would happen during the electrical and plumbing rough-in phase. A mini-split heat pump heating/cooling system is an alternative and a better choice for a detached garage. The unit will cost from $2,000 to $4,000 installed depending on brand and heating/cooling capacity.

Finishing Touches

Item

Average Cost

Bathroom plumbing fixture installation

$2,000 + cost of fixtures

Kitchen cabinet/sink installation

$700

Appliances (water heater, stove, refrigerator, dishwasher)

$2,000 – $5,000 on average per appliance

If you're converting your garage to a bedroom, home office, or utility room, your work is pretty much done, but if you're making a dwelling unit, you'll need:

  • plumbing fixtures
  • cabinets
  • appliances

The cost of necessary bathroom amenities, including a toilet, shower, vanity, and sink, depends on your style choices but figure at least $2,000 to install all of them. The kitchen sink and cabinet is similarly subject to your preferences. A store-bought sink/cabinet combo can be professionally installed for less than $700, but if you want a fully appointed kitchen with standard cabinets and countertops, the room could cost 10 times that.

Last on the list are necessary appliances, such as:

  • water heater
  • stove
  • refrigerator
  • dishwasher

If you buy these new, count on spending upward of $2,000 to $5,000 for midgrade units or quite a bit more for high-end models. Once the appliances are in place, your new dwelling unit is ready for a final inspection before it's legal to live in or rent out.

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