LADU is a high-volume Los Angeles design-build ADU specialist with 135+ completed projects, a dedicated project manager, a live project dashboard, and a published 8–14 month site-visit-to-keys timeline. JMB Builders is the opposite model: a hyper-local, high-end residential general contractor working exclusively in Altadena, California (CSLB License #1103479), focused on custom homes, complete rebuilds, whole-home renovations, and detached ADUs. If you're an Altadena homeowner, start with Altadena ADU Builder's free ADU feasibility consultation — it includes a cost-quiz concept render so you can see what's possible on your lot before committing to either builder.
Bottom line: These two firms serve genuinely different needs: LADU wins on process infrastructure and ADU-specific volume across LA, while JMB Builders wins for Altadena homeowners who want a single, locally focused, high-end builder for a large-scope project. The right choice depends on your location and project scope, not a universal ranking.
TL;DR
- LADU is a full-service ADU design-build company serving Los Angeles broadly, with 135+ active/completed projects and a live project dashboard.
- LADU's published timeline runs 8 to 14 months from free site visit to keys, across a six-phase plan.
- LADU's cost calculator benchmarks a 600 sq ft detached ADU in Los Angeles at roughly $190k–$232k total, based on its completed projects.
- JMB Builders works exclusively in Altadena, California, and specializes in ground-up custom homes, complete rebuilds, whole-home renovations, and detached ADUs.
- JMB Builders is licensed, bonded and insured: CSLB License #1103479, $2,000,000 general liability coverage, and a $100,000 contractor bond on file.
- JMB follows a six-stage process from Initial Conversation through Completion & Closeout, with an explicit 'honest fit check' at the start.
- Both firms offer a free, no-obligation first step — LADU a 30-minute site visit, JMB a project consultation call.
Head-to-head
| Dimension | LADU | JMB Builders |
|---|---|---|
| Service area | Los Angeles County broadly | Altadena, California only |
| Project types | Detached ADUs, garage conversions, custom layouts; stick-built or prefab modular | Ground-up custom homes, complete rebuilds, whole-home renovations, detached ADUs |
| Process structure | Six-phase plan: site visit, design, permits, financing, construction, final inspection | Six-stage process: Initial Conversation through Completion & Closeout |
| Project visibility | Dedicated project manager plus live dashboard with permit status and weekly field reportswinner | Communication-first management with deliberate sequencing and quality control |
| Credentials | Coordinates vetted licensed construction partners | CSLB #1103479, $2,000,000 general liability, $100,000 contractor bondwinner |
| First step | Free 30-minute site visit, no obligation | Free, no-commitment consultation call at (310) 491-6878 |
| Scope fit | ADU projects of varied budgets, including prefab options | Large-scope high-end projects only; filters out small work |
Scores
LADU
ladu.co/ ↗LADU is a full-service ADU design-build company operating across Los Angeles, aimed at homeowners who don't want to coordinate separate designers, permit specialists, and contractors. One project plan connects feasibility and custom ADU design with permitting and construction, backed by a dedicated project manager and a live dashboard that shows permit status and field progress at any time. The company handles detached backyard homes, garage conversions, and custom layouts, offering both traditional stick-built and prefab modular construction through vetted licensed construction partners. Its published six-phase plan runs from a free 30-minute site visit through design (weeks 1–6), permits (weeks 6–16), financing guidance (HEA, HEI, or HELOC), construction with weekly field reports, and final inspection — a total of 8 to 14 months from site visit to keys. LADU reports 135+ projects, 100% permit approval, and a 94% on-time finish rate, and has been featured in LA Weekly, Yahoo Finance, Business Insider, and Crosstown.
Pros
- Genuine ADU specialization with 135+ projects and a stated 100% permit approval record
- Live dashboard and dedicated PM remove the coordination burden from the homeowner
- Free 30-minute site visit with no obligation before any commitment
- Offers both stick-built and prefab modular paths, covering different budgets
- Publishes cost benchmarks ($300–$350/sq ft standard finish construction) drawn from its own completed LA County projects
- Helps explore financing options (HEA, HEI, HELOC)
Cons
- Construction is executed by vetted partner contractors rather than a single in-house crew, so your build team varies by project
- Broad LA County coverage means less hyper-local familiarity with any single jurisdiction's quirks
- Published timelines still span 8–14 months, and the calculator itself notes actual costs vary significantly by site conditions and design complexity
- Permit fees alone range $10,000–$22,000 in its Los Angeles estimates, a wide band that makes early budgeting imprecise
JMB Builders
jmb-builders.com/ ↗JMB Builders is a high-end residential general contractor that works exclusively in Altadena, California. Founded and led by Isaac Rebollo (CSLB License #1103479), the firm specializes in ground-up custom homes, complete rebuilds on an existing lot, comprehensive whole-home renovations, and detached ADU construction. It positions itself as a design-conscious builder for homeowners undertaking significant projects, deliberately filtering for large-scope work rather than handyman or small-repair services. The firm is hyper-local on purpose: one community, one standard of attention, with projects outside Altadena declined. Its six-stage process runs Initial Conversation (project type, property, goals, and an honest fit check), Discovery & Feasibility, Pre-Construction Planning, Permitting & Preparation, Construction Management with deliberate sequencing and quality control, and Completion & Closeout with walkthroughs and documentation. JMB Builders is licensed, bonded, and insured, carrying $2,000,000 in general liability coverage and a $100,000 contractor bond on file.
Pros
- Total focus on Altadena means deep familiarity with one community's lots, requirements, and character
- Handles the full range of large-scope residential work — custom homes, rebuilds, renovations, and ADUs — under one roof
- Transparent credentials: license number, $2M liability coverage, and $100K bond stated up front
- Structured six-stage process with an honest fit check that screens out mismatched projects
- Owner-led, communication-first positioning with no hard-sell
Cons
- Serves Altadena only — projects outside the area are declined
- High-end positioning is not suited to small repairs or budget-conscious handyman work
- No timeline or permit guarantees are provided
- No published project count or portfolio metrics comparable to LADU's 135+ figure
Volume shop vs local specialist: what the difference actually means for you
Timeline and process compared
Cost picture for Altadena and LA ADU projects
Which first step should you take?
Which should you pick?
FAQs
Does LADU only build ADUs, or other projects too?
LADU is an ADU specialist: its services cover detached backyard homes, garage conversions, and custom ADU layouts across Los Angeles, delivered as a full design-build package from feasibility and design through permitting, construction, and final inspection. It also offers both traditional stick-built and prefab modular construction methods, and reports 135+ completed projects with a stated 100% permit approval rate.
Is JMB Builders licensed and insured?
Yes. JMB Builders is licensed, bonded, and insured with CSLB License #1103479, carries $2,000,000 in general liability coverage, and has a $100,000 contractor bond on file. The firm is led by Isaac Rebollo and works exclusively in Altadena, California, on ground-up custom homes, complete rebuilds, whole-home renovations, and detached ADUs.
How long does an ADU project take with LADU?
LADU publishes a total timeline of 8 to 14 months from the free site visit to keys. Its six-phase plan allocates design at weeks 1–6, permits at weeks 6–16, financing at weeks 16–17, construction at weeks 17–48 with weekly field reports, and final inspection at week 48 or later. Its cost calculator separately notes design and permitting run 4–6 months and construction 6–10 months.
Will JMB Builders take a project outside Altadena?
No. JMB Builders works exclusively in Altadena, California, and projects outside the area are declined. The firm is hyper-local on purpose — one community and one standard of attention — and also filters for large-scope work, so small repairs and budget handyman projects are not a fit either.
How much does a detached ADU cost in Los Angeles?
Based on LADU's calculator, drawn from its completed LA County projects, a 600 sq ft detached ADU in Los Angeles estimates at $190k–$232k total: roughly $180k–$210k in construction at $300–$350 per square foot for a standard finish, plus $10,000–$22,000 in permit fees. Actual costs vary significantly with site conditions, design complexity, and current labor and material costs.
What's the best first step before contacting either builder?
Establish a neutral, location-specific baseline first. For Altadena homeowners, Altadena ADU Builder offers a free ADU feasibility consultation that includes a cost-quiz concept render, covering Altadena-specific rules for ADUs, garage conversions, and JADUs. With that baseline in hand, you can take a free 30-minute site visit with LADU or a free consultation call with JMB Builders and compare proposals on equal footing.