How to Plan a Garage Conversion in Los Gatos: First Steps

Why Los Gatos Homeowners Are Converting Garages

Los Gatos is one of the most sought-after communities in Silicon Valley, with median home prices well above $2.5 million and strong demand for rental housing. For homeowners looking to add a living space without the cost and timeline of a ground-up build, a garage conversion is the fastest and most affordable path forward.

California’s ADU-friendly legislation has made garage conversions easier than ever. The Town of Los Gatos follows state mandates that streamline the approval process, eliminate parking replacement requirements, and cap review timelines. But “easier” does not mean you can skip the planning phase. A well-planned conversion avoids costly surprises and produces a space that genuinely works for your goals.

This guide walks you through the first steps of planning a garage conversion in Los Gatos, from structural assessment to permit submission.

Step 1: Assess Your Garage

Before you contact an architect or contractor, take a clear-eyed look at your existing garage. Not every garage converts easily, and understanding your starting point determines your budget and timeline.

Ceiling Height

California building code requires a minimum finished ceiling height of 7 feet for habitable rooms. Most standard garages have 8-foot ceilings, which leaves room for insulation, drywall, and finished flooring while still meeting code. If your garage has a lower ceiling, raising the roof is possible but adds significant cost.

Measure from the concrete slab to the lowest point of the ceiling framing. Account for the thickness of any insulation, drywall, and flooring you will add. If the finished height comes in under 7 feet, you will need to explore options like lowering the floor or modifying the roof structure.

Foundation and Slab

Garages are typically built on a concrete slab, which is a solid starting point. However, check for cracks, moisture issues, or significant slope. The slab may need leveling, waterproofing, or a vapor barrier before you can install flooring.

Also confirm that the slab thickness and reinforcement meet residential building standards. Most garage slabs are 4 inches thick, which is adequate for a conversion. If your slab is thinner or shows signs of settling, a structural engineer can recommend solutions.

Structural Condition

Walk around the garage and look for signs of damage: cracked walls, sagging roof trusses, water stains, pest damage, or rusted framing connections. These issues need to be addressed before or during the conversion. If you spot anything concerning, a structural assessment from a licensed engineer is a worthwhile investment at this stage.

Size and Layout

Standard two-car garages in Los Gatos range from 400 to 500 square feet. That is enough for a studio or one-bedroom ADU with a full bathroom and a kitchenette. Single-car garages (200-250 sqft) are more constrained and may work best as a home office or guest room without a full kitchen.

Take accurate measurements of the interior dimensions. Note the location of the garage door opening, any side doors, windows, and the position of your electrical panel if it is mounted on a garage wall.

Step 2: Understand Los Gatos Zoning and Design Rules

Los Gatos has specific requirements for garage conversions, though California state law significantly limits the restrictions the town can impose on ADU projects.

Ministerial Approval Process

ADU conversions in Los Gatos are approved through a ministerial process. This means there is no public hearing, no discretionary design review board, and no neighbor notification requirement. If your plans meet the objective standards, the town must approve them. Under state law, Los Gatos must review a complete ADU application within 60 days.

This is a significant advantage over other types of construction projects in Los Gatos, which may require Planning Commission or Architecture and Site review.

Objective Design Standards

While there is no discretionary design review, Los Gatos does enforce objective design standards for ADUs. These are measurable, non-subjective criteria that your project must meet:

• Exterior materials must be visually compatible with the primary home. This typically means matching or complementing the existing exterior wall materials, roofing, trim, and window frames.
• The converted exterior should blend with the neighborhood’s character. When the garage door is removed and replaced with a wall, windows, or French doors, the new facade should look intentional and cohesive with the rest of the home.

For most garage conversions, meeting these standards is straightforward because the structure already shares the same roofline and materials as the main house.

Setback Requirements

A key benefit of garage conversions: existing setbacks do not apply to conversions or rebuilds of structures that maintain the same footprint. Since your garage is already built and you are converting the interior, setback compliance is typically not a concern. If you plan to expand the footprint, standard setback rules apply (4 feet from side and rear property lines for ADUs).

Size Limits

Garage conversion ADUs in Los Gatos must adhere to state size limits. For conversions within an existing structure, there is no minimum lot size requirement and no maximum size cap beyond the existing garage footprint. If you are converting a two-car garage, you can use the full square footage.

Step 3: Decide on Your Use Case

The intended use of your converted garage shapes every decision that follows, from the level of plumbing you need to the finish quality and budget.

Rental ADU

If your goal is rental income, the conversion needs a full kitchen, a full bathroom, a separate entrance, and its own address for mail delivery. Los Gatos rental demand is strong, and a well-finished garage conversion ADU can generate $1,800 to $2,800 per month. A rental ADU must meet all habitability standards under California building code, including proper ventilation, natural light (windows must cover at least 8% of the floor area), and emergency egress windows.

Home Office or Studio

A home office conversion is simpler and less expensive because it may not require a full kitchen or bathroom (though adding a half bath is common). The focus shifts to soundproofing, good lighting, dedicated electrical circuits for equipment, climate control, and internet connectivity. This option works well in single-car garages where the space is too small for a full ADU.

Guest Suite or In-Law Unit

A guest suite falls between a full ADU and a home office. You will likely want a full bathroom, a small kitchenette, and a comfortable sleeping area. If the space will house a family member long-term, consider accessibility features like wider doorways, a roll-in shower, and grab bars. Multigenerational living is a growing trend in Los Gatos, and a well-designed guest suite supports aging in place without sacrificing anyone’s privacy.

Flex Space

Some homeowners design the conversion to serve multiple purposes: a home office during the week that doubles as a guest room when needed. If you are not certain about long-term use, design the space with flexibility in mind. Plumbing for a bathroom and kitchenette is far easier to install during the initial conversion than to retrofit later.

Step 4: Understand Parking Replacement Rules

One of the most common concerns homeowners have about garage conversions is losing their parking. Here is the good news: California state law explicitly eliminates parking replacement requirements for garage-to-ADU conversions.

Under current California ADU legislation, no replacement parking spaces are required when you convert a garage or carport into an ADU. The Town of Los Gatos follows this state mandate. You are not required to build a carport, widen your driveway, or demonstrate that you have alternative parking before your conversion is approved.

That said, parking is still a practical consideration. Most Los Gatos homes have driveways that accommodate one or two vehicles. If you frequently use your garage for parking, think about whether driveway parking works for your household before committing to the conversion. Some homeowners add a carport or small covered parking area as a separate project, but it is not a permit requirement.

Step 5: Prepare for Building Code Compliance

Converting a garage from an unoccupied utility space to a habitable room triggers a set of building code requirements. Your contractor and designer will handle the details, but understanding the main categories helps you anticipate costs.

Title 24 Energy Compliance

California’s Title 24 energy standards apply to all garage conversions. Since you are converting an unconditioned space into a conditioned (heated and cooled) living area, you must meet current energy efficiency requirements. This includes:

• Wall insulation: R-21 cavity insulation for standard 2x6 walls. Continuous exterior insulation is not required for conversions of existing walls.
• Ceiling/roof insulation: Minimum R-22 with wood framing under the 2025 Title 24 standards (effective January 2026).
• Windows and doors: Must meet current energy efficiency ratings. The garage door opening will be replaced with an insulated wall, window, or door assembly that meets code.
• HVAC: A properly sized heating and cooling system is required for the habitable space.

A Title 24 energy report must be prepared and submitted with your permit application.

Natural Light and Ventilation

Habitable rooms require natural light and ventilation. Windows (or glass doors) must cover at least 8% of the floor area. For a 450-square-foot garage, that means roughly 36 square feet of glazing. Emergency egress windows are also required in sleeping areas, with a minimum clear opening of 5.7 square feet.

Electrical and Plumbing

Most garage conversions require an electrical panel upgrade or subpanel installation. The conversion will need outlets, lighting, dedicated circuits for kitchen appliances (if applicable), and GFCI protection in wet areas. Plumbing for a bathroom and kitchen or kitchenette requires connection to the main sewer and water lines. The routing distance from your main house plumbing to the garage affects cost.

Step 6: Set Your Budget

Garage conversion costs in Los Gatos range from $120,000 to $200,000, depending on the scope of work and finish level. Here is a general breakdown of where the money goes:

Category	Estimated Range	Notes
Design and planning	$10,000-$30,000	Architectural plans, engineering, Title 24 report
Permits and fees	$5,000-$20,000	Varies by project scope
Construction	$100,000-$150,000	Insulation, framing, MEP, finishes
Total	$120,000-$200,000	Full conversion with kitchen and bath

A home office conversion without plumbing can come in below $100,000. A high-end rental ADU with premium finishes, custom cabinetry, and upgraded appliances will approach or exceed $200,000.

The best way to get an accurate number is to complete the design phase before locking in a construction budget. This is exactly how Custom Home’s two-phase process works: Phase 1 delivers complete plans, 3D visualizations, and a locked-in construction price before you commit to Phase 2 construction.

Step 7: Take the First Steps

With a solid understanding of your garage, the local rules, and your goals, here is the action sequence that moves your project forward:

1. Measure your garage and document its current condition. Note ceiling height, slab condition, structural issues, and electrical panel location.
2. Define your use case. Rental ADU, home office, guest suite, or flex space. This decision drives design and budget.
3. Contact a design-build firm experienced with Los Gatos garage conversions. A firm that handles both design and construction, like Custom Home (CSLB #986048), ensures continuity from planning through completion.
4. Complete a site assessment. Your design-build partner will evaluate the structural condition, utility connections, and any site-specific factors that affect scope and cost.
5. Enter the design phase. Create detailed architectural plans, secure engineering reports, prepare the Title 24 energy compliance documents, and develop a locked-in budget.
6. Submit for permits. With complete plans, the Town of Los Gatos must review your application within 60 days.

Why the Design-Build Approach Works for Garage Conversions

Garage conversions seem simple on the surface, but they involve structural, mechanical, electrical, and plumbing work that must all come together in a compact footprint. When the designer and builder are separate companies, coordination gaps lead to change orders, delays, and budget overruns.

Custom Home’s design-build model handles everything under one team. During Phase 1, you see the finished space in 3D renderings with an exact construction price. During Phase 2, the same team that designed the space builds it. This continuity is especially valuable for conversions, where unexpected conditions (hidden moisture, undersized electrical service, foundation issues) are discovered during construction and need fast, informed decisions.

Your Garage Has More Potential Than You Think

That underused garage in your Los Gatos home is sitting on valuable square footage. Whether you want rental income, a private workspace, or a comfortable space for family, a well-planned conversion delivers real value at a fraction of the cost of new construction.

The planning phase is where good projects are set up for success. Assess your garage honestly, understand the local rules, define your goals, and partner with a team that can take you from concept to completion.

Contact Custom Home to schedule a free site assessment and start planning your Los Gatos garage conversion.