Turning your garage into an ADU is one of the best ways to take advantage of all of your property’s space, boost your home’s value, and set up a new income flow. However, a garage-to-ADU conversion still has requirements that homeowners should be aware of.

Below, we’ll talk about what to keep in mind for this type of renovation and how working with a professional crew can make all the difference.

What is an ADU?

An ADU (Accessory Dwelling Unit) is a separate living unit on the same lot as a primary home. It’s basically an extra house that’s way smaller than the main house on the lot. They’re sometimes called granny flats, in-law units, backyard cottages, or garage conversion apartments.

The idea is to provide an independent living space that can be rented, used by a family, or serve as an extra living space for friends, guests, families, etc. 

A garage conversion into an ADU should typically result in a structure that has: 

  • Kitchen
  • Bathroom
  • Sleeping space
  • Entrance
  • Utilities
  • Living area

That’s not a strict rule, though. Many ADUs will have more or fewer of the spaces mentioned above. There are many different ADU layouts a homeowner could go with, but the basic idea is to provide enough room for living and sleeping.

Why convert a garage into an ADU?

Because it’s usually way cheaper than building an ADU from scratch. Keep in mind that, in most cases, converting an existing garage into an ADU saves a lot of money since much of the structure is already in place.

Key Benefits

  • Cost savings vs new build: Using the existing foundation, walls, roof (if structurally sound), and footprint can reduce both materials and labor.
  • Increased property value and rental potential: A well-designed ADU can make your lot’s resale value go up, especially in areas with housing demand.
  • Flexibility: ADUs can be used as a guest house, home office, rental unit for passive income, space for aging parents, etc.
  • Using your land effectively: Rather than lifting a new structure somewhere else on the lot, renovating the space you already occupy means fewer surprises, less site work, and less regulatory paperwork.

Common challenges when converting a garage into an ADU

Although renovating a garage to make an ADU out of it cuts a lot of corners and extra costs, there are obstacles to be aware of. How easy the conversion will be really depends on the garage’s build, local laws, and ADU design.

  • Zoning and permits: There are local laws that might require some paperwork and extra bureaucracy. This includes rules on setbacks, parking requirements, utility hookups, and safety regulations. What is allowed in one city might not be in another. So, check the local laws.
  • Structural & building code upgrades: Many garages aren’t built with full insulation, plumbing, or electrical capacity. Changes like reinforcing floors, adjusting roofs, installing or relocating plumbing, and bringing in HVAC can increase costs.
  • Utility costs & connections: If the garage is detached or far from existing water/sewer/electric lines, connecting it can be pricey. Commonly, the garage needs electrical upgrades to support the demands of a home.
  • Finishing, interior comforts, and design: Windows, heating/cooling, sound insulation, and finishes all add up. There’s a huge difference between a barebones ADU and a luxury finish.

Contractor or DIY for my ADU conversion?

To ensure your garage conversion ADU is safe, legal, efficient, and worth your investment, the best route is to find the right ADU contractor. They’ll give you a better snapshot of the budget, design freedom, paperwork, and return on investment projection.

  • They can help with site assessment (is the existing garage structurally sound? What foundational or roof renovations are needed?)
  • They’ll guide you through permitting, local codes, and ensure the conversion is in line with all safety, energy, and building codes.
  • They can provide design input to maximize light, ventilation, access, layout, etc.
  • Good contractors help stay on budget and spot hidden costs (utility upgrades, inspections, structural repairs, etc.).

A specialist hugely lowers the chance of surprises, saving you money in the long run and making the process faster.

Example Costs in a Garage to ADU Conversion

Costs vary a lot in different states, especially for permit fees. This is why it’s essential to check the fees in your specific state and city. The building costs can vary depending on the local demand. Here are two cost examples that you might expect if you’re converting a garage into an ADU in Fresno or Los Angeles:

  • In Fresno, CA, garages being converted to ADUs typically cost between US $125–200 / sq ft, depending on design and finishes. Permit fees in Fresno for such projects may run from US $2,500 to $4,500, depending on the scope.
  • In Los Angeles, permit & fee costs alone for a garage conversion ADU can be US $1,400 to $8,000, depending on size and complexity.

Conclusion

Converting a garage into an ADU can be a win-win: extra living space, potential income, and greater property value. After all, the garage’s structure is already there, and that’ll help you cut a lot of corners. But success depends on careful planning, compliance with local rules, realistic budgeting, and hiring someone who knows the ADU process well.