Location	Normal Heights, San Diego, CA 92116
Project Type	Expansion of an existing ADU into the attached garage, plus full interior remodel of the ADU; remaining garage converted to workshop, laundry, and storage
ADU Size	1,200 sq ft after expansion — the City of San Diego’s full ADU allowance for this configuration
ADU Layout	2 Bedroom / 2 Bath (new master bath + new bathroom) · new living room & dining room · improved kitchen · master closet · dedicated storage
Special Features	11-ft folding glass door wall to a landscaped patio, French doors, 1-hr fire-rated separation between dwellings, grab-bar-ready bathrooms, high-performance windows (U-0.30)
Status	In design & permitting — 2026
Typical Investment	Conversion-class work is the least expensive ADU square footage in San Diego — the structure, slab, and roof already exist — running well below the $350–$500+/sq ft of ground-up ADU construction; full-scope expansions with new baths land in the low-to-mid six figures
Jurisdiction	City of San Diego — standard ADU permit
Est. Timeline	~8–12 months, design through construction

The Project

This Normal Heights property already did what most San Diego homeowners are still planning: it has a second dwelling. What it didn’t have is a second dwelling that lives well. The existing ADU was tight, the garage next to it was doing what most garages do — storing things nobody had touched in years — and the two shared a wall that was really a boundary between “done” and “potential.”

The design erases that boundary. The ADU expands sideways into the garage footprint, growing to a full 1,200 square feet — the maximum the City of San Diego allows for this configuration. The former garage bay becomes the unit’s new living room, anchored by an 11-foot folding glass door wall that opens the whole room to a landscaped patio; the old garage door gets closed off and finished as real exterior wall. Behind it, the plan adds a proper dining room, a new master bathroom, a second new bathroom, and a walk-in master closet, while the existing kitchen and both bedrooms get fully reworked. It’s not an ADU with an extension bolted on — it’s a re-planned 2-bed, 2-bath home that happens to reuse a garage’s bones.

And the main house gives up less than you’d think. The remaining garage strip is converted into a workshop, a laundry room, and dedicated storage with built-in shelving — so the functions a garage actually provides survive, reorganized into less space. That’s the quiet insight of this project: on a mid-city lot, the garage isn’t parking, it’s the cheapest unbuilt square footage you own, and it can serve both dwellings at once.

The Challenge

Merging a dwelling into a garage sounds simple — the walls and roof are already there. What makes it real construction is everything you can’t see: code separation between two homes under connected roofs, an old slab that was never meant to be lived on, and the choreography of growing one unit without degrading the other.

Project Timeline

The project is in active design and permitting as of summer 2026; construction phases below are projected from our typical conversion-class schedule in the City of San Diego.

The Cost

We publish exact figures on completed projects, not active ones — here’s the market context instead. Conversion-class ADU work is the least expensive square footage you can add in San Diego, for a simple reason: the three most expensive things in construction — foundation, structure, and roof — already exist. Ground-up ADU construction runs $350–$500+ per square foot; expanding into an existing garage avoids most of that. What the budget actually buys here is the unglamorous work that makes it legal and livable: slab repair and leveling, 1-hour fire-rated separation assemblies with sound insulation, two new bathrooms’ worth of plumbing, a reworked kitchen, and a folding door wall replacing a garage door. A full-scope expansion-and-remodel like this — two new baths, new kitchen work, every room touched — lands in the low-to-mid six figures, well below what the same finished square footage would cost as new construction.

One honest warning for anyone comparing bids on garage conversions: the cheap quote usually prices the cosmetic version — drywall over the existing slab, no fire separation upgrade, no sound insulation, minimal slab work. That version haunts you at inspection, at refinance, and at sale. The separation assemblies and slab work aren’t extras; they’re the project.

Want a real number for your garage or ADU? Get a free estimate →

The Value Math: The Cheapest Square Footage You Already Own

Normal Heights is a strong neighborhood to run this math in. It’s one of San Diego’s most rental-dense mid-city neighborhoods — walkable to the Adams Avenue corridor, priced below the coastal markets, with recent sale prints ranging roughly from the mid-$700s to over $1,100 per square foot depending on the month and property mix (it’s a small neighborhood; monthly medians swing hard). Against conversion-class construction costs, expanding into an existing garage adds finished, permitted square footage at a fraction of what the market values it at.

The income side is where this project’s logic sharpens. Two-bedroom units in Normal Heights currently rent for roughly $2,150–$3,400 per month, and a newly rebuilt 1,200 sq ft ADU — two full baths, in-unit laundry hookups, a folding glass wall to a private landscaped patio — competes at the top of that range, against apartment stock that mostly can’t offer any of it. An under-used small ADU plus a storage garage becomes a premium rental (or a genuinely comfortable multigenerational home) without adding a single square foot of new footprint to the lot.

There’s also a longevity play built into the drawings: every bathroom wall carries concealed grab-bar reinforcement. It costs almost nothing during framing and means the unit can serve aging parents — or the owners themselves someday — without a retrofit. In a neighborhood where families increasingly keep property across generations, that’s not a detail, it’s a strategy.

The honest caveats, as always: rent depends on finish and timing, neighborhood price data is volatile month to month, and none of this is an appraisal. But the structural argument doesn’t move: finished square footage created inside an existing structure is the best cost-to-value trade in San Diego remodeling.

Design & Permitting

Design is led in-house by our certified interior designer. The brief was to make the expansion invisible — not a garage with furniture in it, but a home where you can’t tell where the original ADU ends and the garage began. That’s why the plan re-organizes everything: the living and dining rooms land in the big open former garage bay where the folding door wall brings the patio in, the bedrooms keep the quiet side, and the new master bath, bathroom, and closet slot into the seam between old and new.

The technical spine of the project is the separation between the two dwellings: 1-hour fire-rated wall and ceiling assemblies running foundation to roof sheathing, insulated to an STC 45 sound rating. It’s the difference between two homes and one home with a roommate problem — and it’s detailed on its own sheet in the permit set. Underfoot, the existing garage slab gets repaired and leveled with waterproofing and crack-prevention membrane before finish flooring goes down; exactly the kind of work a cosmetic conversion skips and a buyer’s inspector finds.

The exterior strategy keeps the property reading as one coherent single-story composition — matching rooflines, matching stucco, high-performance windows throughout — so from the street, nothing announces that the lot works twice as hard as its neighbors. The renders on this page are the approved design direction, landscape included.

Permitting runs through the City of San Diego on the standard ADU track. Because the expansion stays within the existing structure’s footprint and the ADU lands exactly at its 1,200 sq ft allowance, the review question isn’t zoning — it’s execution: fire separation, egress, energy compliance. All of it is resolved in the drawings before submittal.

Expand Your ADU vs. Build New vs. Basic Garage Conversion

If your lot already has an ADU — or a garage — you have three ways to add livable square footage. They’re not the same project.

Factor	ADU Expansion + Remodel	New Detached ADU	Cosmetic Garage Conversion
Cost Per Sq Ft	Lowest for full-scope work — structure, slab, and roof already exist	$350–$500+/sq ft ground-up, plus site work and utilities	Cheapest upfront — and priced that way for a reason
Code & Quality	Full fire separation, sound insulation, slab remediation, new systems	All-new construction to current code	Often skips separation, sound, and slab work — surfaces at inspection or resale
Yard Impact	None — footprint unchanged	Consumes yard area	None
Timeline	~8–12 months design through construction	~12–18 months	Fastest — weeks to a few months
End Result	A re-planned, full-size 1,200 sq ft home	A second structure, maximum independence	A garage that looks like a room
Best For	Lots that already have an ADU or attached garage with more potential than polish	Larger lots adding a first second-unit with yard to spare	Short-term budgets willing to trade quality for speed

Project Gallery

ADU Expansions in San Diego — Frequently Asked Questions

Keep Exploring

IL Total Design And Build · CSLB License #1058676 · San Diego, CA · iltotaldesign.com
Project in design and permitting as of July 2026; construction phases and durations shown are projections based on typical City of San Diego schedules for conversion-class ADU projects. Cost figures are current market ranges, not a quote for this or any project. Neighborhood price and rental figures are drawn from recent public market data and listings (Redfin, Zumper, Apartments.com and MLS-based sources, 2025–2026) and change over time; nothing on this page is an appraisal, a rental guarantee, a project bid, or legal or financial advice. Verify current requirements with your jurisdiction before committing to a scope. Last updated: July 2026.