Garage Conversion ADU in West Covina - Plans, Permits & Build, One Fixed Price

Fast, Reliable Garage Conversion ADU Across West Covina

A garage conversion ADU in West Covina typically runs $145,000-$190,000 all-in, from the first site measure through final inspection. That’s the written price you get from Ellery ADU Studio before any work begins, and it stays locked under Haven Standard Clause 1. If you live in the ranch-tract neighborhoods that define West Covina, your detached garage was built on the same slab as your house between 1955 and 1972, which means your conversion is presumptively approvable under current state ADU law. No discretionary design review. No hearing. Just the structural and utility work, done to the permit set we draw and the price we write before you sign. Call (971) 497-2402 and we’ll walk you through what your specific lot needs.

Call (971) 497-2402

We’re a design-build studio, not a middleman. The drawings, the permit set, and the construction are one contract at one written price. That matters in West Covina because the homes here are so consistent that a contractor who’s done twenty conversions in your zip code already knows your floor plan. The tradeoff is that the cheapest bids in this city routinely skip the three upgrades that actually make a garage livable: slab insulation, inland-rated HVAC, and the electrical panel swap the city will require anyway. We don’t skip them. We write them into the price.

Why Ellery ADU Studio Is West Covina’s Preferred Garage Conversion ADU Company

We’ve designed, permitted, and built over 900 ADUs since 2015, the year California’s ADU permitting landscape shifted. In West Covina, that experience translates directly: the detached two-car garages on your 7,000-9,000 sq ft lots are nearly identical from South Hills to Woodside to the neighborhoods off Amar Road. Same slab-on-grade construction. Same 100-amp panel. Same rear-lot placement. That consistency is why our crews move through West Covina efficiently, and why our written prices here are tighter than they are in cities with mixed housing stock.

Every project we run is governed by The Haven Standard. Written price before work starts, per Clause 1. Documented photo record on every visit, per Clause 3. A 365-Day Done Right Promise, per Clause 7: if the finished ADU is not built to the permitted drawings, we make it right in writing before the project starts. Nadia Ellery, who leads the studio, reviews every West Covina permit set personally before it goes to the city. That’s not a sales pitch. It’s the part of the job where 100-amp panels and missing slab insulation get caught before they become change orders.

When you call (971) 497-2402, a live person answers. Not a voicemail queue. If you already have a written estimate from another contractor, bring it to us for a Free Second Opinion. We’ll tell you what’s missing from the number, and we’ll do it in writing.

How West Covina’s Slab Ranches Decide Your Garage ADU

Your Garage Conversion ADU starts with a slab, not a foundation. The ranch tract homes that cover nearly every West Covina neighborhood between 1955 and 1972 were built on poured concrete slabs, with detached two-car garages poured on the same slab as the main house. No crawlspace. No raised floor. Under California’s current ADU statutes, that configuration is treated as presumptively approvable for garage-conversion ADUs with minimal discretionary review. In plain English: the city has already decided the answer is yes, which is why West Covina has some of the most ADU-ready housing inventory in the eastern San Gabriel Valley.

But the slab is also where the cheap bids fall apart. A concrete slab with no thermal break is a floor that stays cold all winter and radiates heat all summer. On a job in the South Hills neighborhood, we converted a 1963 detached garage into a JADU. The original slab had no insulation, so we saw-cut the perimeter, installed 2-inch rigid foam board, and poured a new topping slab before framing. The homeowner had already gotten two bids from contractors who planned to build directly on the old slab. We showed them the January floor-surface temperature reading from a neighboring conversion that skipped insulation: 47°F. That’s not a comfort preference. That’s a defect you’d be paying to live with.

Our Garage Conversion ADU Services in West Covina

Detached Garage Conversion

This is the most common conversion in West Covina, because the city’s ranch tracts were built with detached two-car garages at the rear of nearly every lot. We handle the full conversion under one contract: structural reinforcement of the existing slab, insulation under a new topping slab, electrical service upgrade from the original 100-amp panel, HVAC sized for inland heat, and the permit set the city of West Covina reviews. The permit set is the product. Everything else follows from it.

Garage JADU

A Junior ADU inside your existing garage footprint can work when the lot won’t support a full conversion or when you want to keep part of the garage for storage. The same slab insulation and electrical issues apply, and in West Covina’s 1960s construction, the JADU path often simplifies sewer connection because you’re tying into the main house’s existing waste line. We draw the partition, the bathroom, and the mechanical run as one coordinated set.

Garage Partition and Bathroom Add

Some West Covina homeowners want rental income without giving up the entire garage. A partition wall and a compact bathroom can turn half the garage into a studio space while the other half stays as storage or a workshop. The trick is the plumbing: your garage slab sits at ground level, so the waste line height matters more than it does in a new detached ADU. We spec the bathroom location to work with your existing sewer lateral before we ever frame a wall.

Attached Garage Conversion and Carport Conversion

Attached garages are less common in West Covina’s older tracts, but they exist, and they’re simpler on utilities because the house electrical and plumbing are adjacent. Carport conversions are the most budget-sensitive option: the slab is already there, but it was never intended to carry wall loads, so we check the slab thickness and reinforcing before we commit to a written price. In West Covina’s 1950s and 1960s carports, that check matters.

Trusted Brands We Service in West Covina

Our crews work with the prefab and modular systems West Covina homeowners ask about most: Cover for panelized wall systems, Abodu for turnkey ADU shells, and James Hardie siding when we’re matching the existing house’s exterior. We specify and coordinate these systems within the same single contract, so the prefab shell, the site work, and the utilities all land on one written price. If you’re considering a prefab garage conversion in West Covina, we coordinate the system and the permit set together, rather than leaving you to arbitrate between the factory and the foundation crew.

Common Garage Conversion ADU Problems We See in West Covina Homes

• Missing slab insulation under the topping slab. Contractors who convert directly on the original 1960s slab skip the rigid foam board, and tenants end up with a floor that reads 47°F in January. We insulate before we frame, every time.
• Undersized mini-splits spec’d for coastal LA, not West Covina. A 1-ton unit sized for Santa Monica cannot hold 72°F when West Covina hits 105°F in August. We size for inland heat loads, which means a 2-ton unit for a 400 sq ft garage ADU here is not upselling. It’s the math.
• Original 100-amp panels failing the city’s ADU electrical review. Nearly every 1960s ranch in West Covina still has a 100-amp panel. The city will not permit ADU electrical service on it. That’s a $3,000-$5,000 upgrade that cheap bids leave out and later spring as a change order. We include it in the written price.
• No documented photo record of what was actually built. If there’s ever a question about the work, you should have evidence. Under The Haven Standard, every visit includes a documented photo record, so you see what we found and what we did, not a summary of how it went.

Pricing for Garage Conversion ADU in West Covina, CA

We Also Serve Cities Near West Covina

Our crews serve West Covina plus the surrounding eastern San Gabriel Valley cities: La Puente, Covina, Baldwin Park, and Azusa. The housing stock in these cities follows the same 1955-1975 ranch-tract pattern, so the slab, panel, and HVAC considerations are consistent across the area.

FAQs - Garage Conversion ADU in West Covina