Room additions & ADUs in El Cajon, CA
Room additions, second stories, ADUs, garage conversions, and whole-home remodels. We handle design, structural engineering, permits, and the full build.
Best home additions in El Cajon, CA
We build room additions, ADUs, and whole-home remodels across El Cajon and San Diego County. From a single-room bump-out to a detached ADU or a full second story, we handle the design, structural engineering, permitting, and construction with our in-house crew. Most additions run 3 to 6 months from permit to final inspection.
What's included in home additions in El Cajon
Room additions & bump-outs in El Cajon
Adding square footage for a bedroom, family room, or larger kitchen. We handle the foundation, framing, roof tie-in, and finishes.
ADUs & granny flats in El Cajon
Detached and attached accessory dwelling units under California's ADU laws, from studio casitas to two-bedroom units, permitted and built to code.
Garage conversions in El Cajon
Turning an attached garage into a bedroom, office, gym, or ADU with proper insulation, egress, and HVAC.
Second-story additions in El Cajon
Building up when you cannot build out. Structural engineering, a new staircase, and a roof line that matches the existing home.
Basement & attic conversions in El Cajon
Finishing usable square footage you already have, with insulation, egress, and code-compliant ceiling heights.
Whole-home remodels in El Cajon
Taking a dated home down to the studs and rebuilding kitchens, baths, flooring, and layout in one coordinated project.
See related serviceHow to start your El Cajon home additions
- 1
Free in-home estimate
We come to your home, walk the space, and listen to what you want out of the home addition. No high-pressure sales, no surprise fees later.
- 2
Honest, written quote
You get a clear line-item quote in plain English. Materials, labor, timeline. If something changes mid-project, you sign off before any extra cost.
- 3
Design and material selection
We help you pick finishes that fit your budget and the existing home. We have trade pricing with local suppliers, which we pass through.
- 4
Build with our in-house crew
The Carrasco family runs the job site every day. No revolving subcontractors. Clean work, daily progress, and someone you can talk to face-to-face.
- 5
Final walkthrough and warranty
We do a punch-list walk with you before final payment. If anything isn't right, we fix it. Our workmanship is backed for a full year after completion.
How much does a room addition or ADU cost in El Cajon?
A room addition in El Cajon runs $40,000 to $100,000 depending on size and whether it includes a bathroom. Garage conversions run $60,000 to $120,000. Detached ADUs run $150,000 to $300,000 depending on size and finishes. Whole-home gut remodels run $100,000 to $250,000. Every project gets a written, line-item quote after the design phase.
Why El Cajon homeowners choose 5 IN 1 for home additions
Home Additions in 6 El Cajon neighborhoods
El Cajon is East County — hotter, drier, and built largely in the 1950s through 1980s. The housing stock is heavy on ranch homes and single-story builds with shake or tile roofs and stucco exteriors. Costs typically run slightly below the coastal cities for labor and permit fees, which we pass through to the client.
We have remodeled El Cajon homes since 1987. The Carrasco family runs every job site, the same in-house crew handles your project from rough-in to final walk, and we pull every permit in your name.
El Cajon neighborhoods we serve
- • Bostonia
- • Fletcher Hills
- • Rancho San Diego
- • El Cajon Village
- • Granite Hills
- • Singing Hills
ZIP codes: 92019, 92020, 92021
Recent home additions projects in El Cajon
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Home Additions in El Cajon: frequently asked questions
How much does a room addition or ADU cost in El Cajon?+
In El Cajon, room additions run $40,000 to $100,000, garage conversions $60,000 to $120,000, and detached ADUs $150,000 to $300,000. Whole-home gut remodels run $100,000 to $250,000. You get a written line-item quote after the design phase.
How long does a room addition or ADU take?+
Plan for 3 to 6 months from permit to final inspection for most additions and ADUs. Design and permitting adds 2 to 4 months before construction starts, and City of San Diego review runs longer than the smaller cities.
Do I need a permit for an addition or ADU in El Cajon?+
Yes. Every addition and ADU in El Cajon needs a permit and plan check. We handle the drawings, structural engineering, and the submittal in your name, and we meet inspectors at each stage.
Can I build an ADU on my El Cajon lot?+
Most single-family and multi-family lots in El Cajon qualify for at least one ADU under current California law, and many also allow a junior ADU. We check your lot, setbacks, and utilities up front and tell you what will actually fit.
What additions add the most value in El Cajon?+
In El Cajon, ADUs top the list because of the rental income and the region's housing demand. Primary-suite additions and garage conversions to living space also return well. We can talk through the numbers for your specific block.
Other remodeling services in El Cajon
Kitchen Remodeling in El Cajon
Full kitchen remodels with cabinets, countertops, flooring, and layout changes. We handle the whole job in-house, from rough-in to final walkthrough.
Bathroom Remodeling in El Cajon
Walk-in showers, tubs, vanities, and tile. We handle plumbing, electrical, framing, and finish work in-house.
Flooring in El Cajon
Luxury vinyl plank, tile, hardwood, and laminate. Single rooms or whole-home installs.
Home Additions near you in San Diego County
Ready to start your El Cajon home additions project?
Free in-home estimate. Honest pricing. Written quote within 48 hours.