How long does LADBS mechanical plan check take for a commercial HVAC project?

For standard commercial TI HVAC projects at LADBS: over-the-counter (OTC) mechanical permits for qualifying scope take 1–3 hours at the counter. Full plan check for projects that exceed OTC thresholds takes 6–14 weeks depending on project complexity and current workload. Projects in the expedited plan check program (additional fee) can reach 3–4 weeks. In 2026, LADBS has implemented partial online plan check submission for mechanical scope - using the ePlan portal for initial submittal can reduce the administrative processing time by 1–2 weeks.

Do I need a separate mechanical permit for a rooftop unit replacement in Los Angeles?

Yes, if the replacement unit is over 5 tons or if any ductwork is modified. LADBS requires a mechanical permit for RTU replacements on commercial buildings. Under the 2025 Energy Code (effective January 1, 2026), most commercial RTU replacements also require heat pump technology and a completed NRCC-MCH form. Simple like-for-like RTU replacements under 5 tons on non-regulated occupancies may qualify for OTC permit processing. When in doubt, call the LADBS mechanical permit counter at the applicable District Office - counter staff can advise on OTC eligibility before you assemble the submittal package.

What documents are required for a commercial HVAC permit in Los Angeles?

For a full plan check commercial HVAC permit at LADBS: (1) mechanical drawings - floor plan with equipment locations, duct routing, equipment schedule, and ventilation calculations; (2) NRCC-MCH (Title 24 Certificate of Compliance - Mechanical); (3) equipment cut sheets with CABEC-listed efficiency ratings; (4) structural calculations for rooftop equipment mounting if equipment weight exceeds threshold; (5) SCAQMD permit application if the project includes combustion equipment (gas furnace, boiler) over the applicable input rating. For restaurant scope, add: hood schedule, grease duct section detail, fire suppression coordination note, and health department plan check application.

What is the SCAQMD permit requirement for commercial HVAC in Los Angeles?

The South Coast Air Quality Management District (SCAQMD) requires air quality permits for combustion equipment operating in the South Coast Air Basin - which covers Los Angeles, Orange, Riverside, and San Bernardino Counties. Commercial HVAC equipment with gas furnace sections above approximately 2 MMBtu/hr input, commercial boilers, and make-up air units with gas heat may require SCAQMD Rule 2201 permits. The permit application is submitted to SCAQMD separately from the LADBS mechanical permit. Budget 4–8 weeks for SCAQMD review on new equipment permits.

Local · Permitting · Los Angeles · Published 2026-06-03

Los Angeles commercial HVAC permit process: a mechanical subcontractor's guide to LADBS plan check

LADBS (Los Angeles Department of Building and Safety) is one of the most complex permitting jurisdictions in California for commercial HVAC work. The OTC vs. full plan check threshold, SCAQMD combustion permits running in parallel, the 2026 Title 24 heat pump documentation layer, and the DPS (Development Services Center) routing for large projects all add time to a LA mechanical permit that does not exist in Sacramento or the Bay Area. Here's the process from an experienced California mechanical contractor.

Commercial mechanical engineering drawings for Los Angeles LADBS plan check submission — LADBS mechanical plan check requires a complete Title 24 NRCC-MCH package, SCAQMD permit application for combustion equipment, and structural calculations for rooftop equipment - a significantly heavier submittal package than most California jurisdictions.

OTC vs. full plan check: the LADBS threshold

LADBS differentiates between over-the-counter (OTC) mechanical permits - issued same-day at the District Office counter - and full plan check permits that require a submittal package reviewed by LADBS mechanical plan checkers.

Qualifying for OTC significantly reduces project schedule risk. OTC qualifying conditions for commercial mechanical scope at LADBS (as of 2026) include:

Like-for-like RTU replacement under 5 tons on an existing commercial occupancy (no duct modifications)
Minor HVAC equipment additions on an existing permitted system (single zone, same duct footprint)
Single exhaust fan replacement or addition on a non-restaurant application

Full plan check is required for: new duct systems or significant modifications; restaurant kitchen ventilation (any Type I hood scope); RTU replacements over 5 tons or requiring Title 24 documentation; projects in designated high-fire zones; and any project where SCAQMD permits are required for combustion equipment.

LADBS plan check timeline - what to actually expect

Published LADBS timelines and experienced timelines differ. Based on project experience in 2025–2026:

Project Type	Standard Plan Check	Expedited (fee)
Standard TI HVAC modification	6–10 weeks	3–4 weeks
Restaurant full mechanical scope	10–16 weeks	5–7 weeks
New commercial construction HVAC	12–20 weeks	6–10 weeks
RTU replacement (full plan check)	4–8 weeks	2–3 weeks

Timelines from submittal to first correction letter. Add 3–6 weeks per correction cycle for complex projects. Complete, correct submittals on first submission are the single most effective schedule tool.

The most common LADBS mechanical plan check rejections

These correction categories account for approximately 70% of first-submission failures on commercial HVAC submittals at LADBS:

Incomplete NRCC-MCH - missing equipment efficiency ratings, missing economizer documentation, or using a non-current Title 24 form version. LADBS requires the 2025 Energy Code version of the NRCC-MCH effective January 1, 2026. Submitting a 2022 form version triggers an automatic correction.
Missing ventilation rate calculations - LADBS mechanical plan checkers require ASHRAE 62.1 ventilation rate calculations for any occupancy change or significant HVAC modification. "Existing" is not an acceptable documentation of ventilation compliance.
Missing structural calculations for rooftop equipment - LADBS requires structural calculations for any rooftop equipment exceeding 400 lbs or installed on a rooftop that has not previously been structurally analyzed for mechanical loading.
Missing SCAQMD permit application reference - for projects with combustion equipment, LADBS plan checkers look for evidence that a SCAQMD permit application has been submitted. Include the SCAQMD application number or a note that the application has been submitted to SCAQMD Rule 2201.
Restaurant scope: missing health department coordination note - LADBS plan checkers flag restaurant mechanical submittals that do not reference the concurrent LACDPH (health department) plan check. Include a note identifying the health department case number.

SCAQMD permits - running in parallel with LADBS

For any LA Basin commercial HVAC project with gas combustion equipment (rooftop unit furnace section, make-up air unit with gas heat, boiler), the SCAQMD Rule 2201 permit application must run concurrently with the LADBS mechanical permit. SCAQMD review timelines for equipment-level permits typically run 4–8 weeks for standard applications. Do not wait for LADBS approval to start the SCAQMD application - these are independent processes that must both complete before equipment can operate.

New equipment must be SCAQMD-certified to meet South Coast air district NOx emission limits. Ultra-low-NOx (14 ng/J) certification is required for most commercial gas heating equipment sold in the South Coast Air Basin after 2019. Verify that the equipment specified for an LA project carries SCAQMD certification before the equipment is ordered - not after delivery.

Working with Sierra Mechanical on LA Basin projects

Sierra Mechanical crews serve the Greater Los Angeles, Orange County, and Inland Empire market from our Rancho Cordova headquarters with a dedicated project manager for LA Basin multi-unit programs. We are experienced with LADBS, LA County, Glendale, Burbank, Pasadena, Inglewood, and South Bay building department processes. Our permit team prepares complete NRCC-MCH documentation packages and files SCAQMD permit applications as part of every LA Basin project.

For the Bay Area permit process comparison, see our guide on Bay Area commercial HVAC permits - SF DBI, Santa Clara, Alameda. For GCs evaluating mechanical subcontractors for LA Basin projects, see our guide to choosing a California mechanical subcontractor.

Request a bid at sierramechcorp.com/contact or call (916) 638-8605.

Permit timelines from project experience 2025–2026. LADBS processes and timelines subject to change - confirm current OTC thresholds with LADBS at project start. SCAQMD Rule 2201 information current as of June 2026.