Garage to ADU Conversion Cost: 2026 Price Breakdown
Quick answer: Converting a garage into an ADU costs about $80,000 to $150,000 in 2026. The price depends on whether plumbing already runs to the garage, the condition of the existing structure, and your finish level. It is usually the cheapest way to add an ADU because the foundation, walls, and roof already exist.
A garage conversion is the smart starting point for a lot of homeowners. You already have a structure. You just need to turn it into a real living space. That head start is why it costs less than building a unit from scratch.
Here is what it actually costs and where the money goes.
What a garage to ADU conversion costs
Compared to a detached new build that often runs $150,000 to $300,000, the savings are real. For the full comparison across ADU types, see how much an ADU costs.
Where the money goes
A garage conversion sounds simple, but a garage is not built to be lived in. Turning it into a code legal home takes real work. Here is the breakdown.
Insulation and walls
A garage usually has no insulation and bare framing. You add insulation, drywall, and finish the walls and ceiling so it holds heat and air conditioning.
Plumbing
This is the swing factor. If water and sewer lines are close, the cost is reasonable. If they have to run a long way to reach the garage, the bill climbs. The kitchen and bathroom both need supply and drain lines.
Electrical
A garage has a few outlets and a light. A home needs a full electrical layout, often an upgraded panel, and proper circuits for the kitchen, heating, and cooling.
Heating and cooling
You need a real system. A mini split is a common, efficient choice for a converted garage.
Kitchen and bathroom
The most expensive part. Cabinets, counters, appliances, a full bathroom, tile, and fixtures. This is also where your finish choices swing the budget the most.
Floor and windows
The slab often gets leveled and finished. Garages have few windows, so you usually add them for light and to meet code for a living space.
Permits
Every conversion needs permits and inspections. Costs vary by city. See our ADU permit cost guide.
How to keep the cost down
- Keep the kitchen and bathroom near existing plumbing lines to cut trenching costs.
- Choose builder grade finishes you can upgrade later.
- Keep the layout simple. Moving walls and plumbing around adds up.
- Get the structure inspected early so surprises do not blow up the budget mid project.
Is a garage conversion worth it
For most homeowners, yes. You get a full living space for less than a new build, you keep your yard, and you add rental income or room for family. The tradeoff is you lose your garage parking and storage, so make sure that works for your household before you start.
The real number comes from a builder walking your garage and checking your plumbing and panel. Get two or three local quotes before you commit.
Frequently asked questions
How much does it cost to convert a garage to an ADU?
About $80,000 to $150,000 in 2026. A basic conversion near existing plumbing sits at the low end. A full conversion with a new kitchen, bath, and nicer finishes sits at the high end.
Is converting a garage cheaper than building a detached ADU?
Yes. A garage conversion reuses the existing foundation, walls, and roof, so it usually costs less than a detached new build, which often runs $150,000 to $300,000 or more.
Do I need a permit to convert my garage into an ADU?
Yes. A garage conversion to a living space requires permits and inspections in nearly every city. Costs and rules vary by location.
How long does a garage conversion take?
Most garage to ADU conversions take about two to four months once permits are approved, depending on the scope and the builder's schedule.
What is the most expensive part of a garage conversion?
The kitchen and bathroom, followed by plumbing if the lines have to run a long distance to reach the garage.
Building ADUs for a living?
If you convert garages into ADUs and want a steady flow of homeowners ready to build, see how ADU marketing for builders works.