Eight MEP Plan Check Corrections That Delay Los Angeles Projects

Most MEP plan check corrections are not engineering failures. They are documentation problems:
something on the drawings does not agree with something else, or a required piece of information is
not where the reviewer expects to find it. The engineering was fine. The submittal was not.

That distinction matters because documentation problems are avoidable, and each correction cycle
costs weeks. Below are the categories we see most often on Los Angeles projects, and what prevents
each one.

1. Energy documentation that disagrees with the drawings

California Title 24, Part 6 compliance documentation has to describe the building that the
drawings actually show. When equipment is swapped late, when a zone is added, or when a system type
changes during design development and the compliance forms are not regenerated, the reviewer sees a
mismatch and issues a correction.

Prevention: treat Title 24 as a live document that tracks design changes, not a
deliverable produced once at the end. If equipment schedules change after the compliance run, the
run has to be redone.

2. Mechanical plan check triggered without the required documentation

LADBS requires plan check for comfort heating or cooling systems at or above 500,000 BTU/h total
input capacity. Projects that cross that threshold late in design, often by adding a system or
upsizing equipment, can find themselves in a review process they had not planned around.

Prevention: establish total input capacity early and know which side of the
threshold you are on before the set is issued.

3. Ventilation rates that cannot be verified from the drawings

Reviewers need to be able to trace required outdoor air from the occupancy and floor area through
to the equipment schedule. When the calculation basis is not shown, or when the schedule reports a
number that cannot be reproduced from the information on the sheet, the correction is a request to
show the work.

Prevention: put the ventilation calculation on the drawings in a form the
reviewer can follow, not only in the calculation package.

4. Electrical load calculations that do not reconcile with the service

Load calculations, panel schedules, and the service size have to agree. Corrections commonly
arise when panel schedules are updated during design but the overall load summary is not, or when
connected and demand loads are presented in a way that cannot be tied back to the service.

Prevention: reconcile the load summary against the panel schedules as a final
check before issue. It is a mechanical step and it catches most of these.

5. Fixture counts and drainage that do not match the architectural plan

Plumbing corrections frequently trace back to a fixture count that no longer matches the
architectural set, usually after a late unit-mix or restroom change. Drainage fixture unit
calculations, vent sizing and water service sizing all flow from that count.

Prevention: re-verify fixture counts against the current architectural backgrounds
immediately before issue, not at the start of the plumbing design.

6. Accessibility clearances at MEP equipment

Controls, thermostats, panels and receptacles are subject to reach-range and clear-floor-space
requirements. These are frequently coordinated on the architectural set and then contradicted by
equipment locations on the MEP drawings.

Prevention: coordinate mounting heights and clearances across disciplines before
issue rather than resolving them in the field.

7. Fire protection that is deferred without saying so

Sprinkler design is often a deferred submittal handled by the installing contractor. Problems
arise when the permit set neither includes the design nor clearly states that it is deferred, or
when the deferred scope is not reflected in the general notes.

Prevention: state explicitly what is deferred and to whom. Ambiguity here
produces a correction every time.

8. Jurisdiction assumed rather than confirmed

Not every project with a Los Angeles mailing address is reviewed by LADBS. Santa Monica,
Culver City, Glendale, Burbank, Pasadena, Long Beach and others operate their own building
departments with their own submittal requirements and their own conventions. A set assembled for
the wrong department will come back.

Prevention: confirm the reviewing authority from the parcel, not the mailing
address, before the set is assembled.

The pattern underneath all of these

Seven of the eight above are coordination and documentation issues rather than engineering
errors. They cluster at the same moment: late design changes that propagate through the drawings
but not through the calculations, schedules and compliance documents that depend on them.

The practical defence is a reconciliation pass before issue, in which schedules, calculations,
compliance documentation and the architectural backgrounds are checked against each other. It is
unglamorous and it is the difference between one review cycle and three.

Related reading

LADBS permitting and Title 24: a
developer’s guide · How to
choose among MEP firms in Los Angeles · Our Los
Angeles MEP engineering practice

Read more