How Long MEP Design Takes for a New Factory: Realistic Stage Durations

For a single-building factory with a frozen process layout, MEP design typically takes about 14 to 26 weeks from the brief to drawings released for construction, with concept, schematic, detailed design and coordination partly overlapping. The range is a planning allowance, not a published norm. Late process data, moving architecture and slow client reviews stretch it more than the drawing work itself.

Where do these durations come from?

There is no regulation or code that sets how long MEP design takes. The allowances below are Secured Engineers' planning ranges for an average industrial building, stated in elapsed weeks and not in effort. They assume the process layout and equipment list are frozen when the stage starts, one building of ordinary complexity, and review turnaround within a week or so. Cleanrooms, multi-storey plants, hazardous areas, large HT substations and brownfield tie-ins push each stage towards the top of its range or beyond. Treat them as a starting point to test against your own project, not a promise.

How long does each design stage take?

Review is a stage in its own right and needs time on the programme. Even the CPWD Works Manual 2022 (clause 8.12) requires structural and electrical-and-mechanical services drawings prepared by a consultant to be authenticated "Good for Construction" by a responsible officer before they are issued to the contractor. A private owner can take the same discipline: name who signs the release, and allow days for that sign-off in every package.

Because the stages overlap, the totals do not add. Detailed design can start on the disciplines whose inputs are settled while schematic design finishes on the rest. The 14 to 26 week figure is the span from brief to released drawings once that overlap is used well.

What dependencies decide whether you land at the low or high end?

• Process and equipment data. Electrical load, heat released into the space, compressed air, process water and exhaust all come from machines the MEP team does not select. If the list arrives in pieces, the load estimate is redone. See how to write the design brief that stops this.
• Architecture and structure. Plant rooms, shafts, roof loads, ceiling heights and bay spacing fix where services can go. A change in column grid reopens routing for every discipline. Layout decisions to lock early lists the ones that matter.
• Supply decisions. Whether you take an HT connection, how much DG capacity you want and whether solar is planned decide the electrical single-line diagram. If these are open, the electrical design waits.
• Client review time. A drawing that waits three weeks for comments adds three weeks. Name one decision-maker and agree turnaround times in the appointment.
• Coordination. Services designed separately collide in ceiling and shaft zones. Overlaying drawings early costs days; discovering the clash on site costs far more. The stage-by-stage deliverables note shows what each release should contain.

Whose clock do the approvals run on?

Design durations are within the consultant's control; authority durations are not. Plan the date each file is complete and submitted, then track the authority separately. Some clocks are stated in the CEA (Measures relating to Safety and Electric Supply) Regulations, 2023. An installation at or below the voltage your state has notified is self-certified, and the report counts as received if the Electrical Inspector has not acknowledged it within three working days (regulation 45). For a multi-storeyed building over fifteen metres, the owner gives at least thirty days' written notice to the Electrical Inspector before applying for supply (regulation 38). Above the notified voltage, the Inspector's own inspection date is not set by the regulations at all.

Fire, pollution board and DISCOM timelines are set by each state, and some are notified under right-to-service rules. The National Single Window System's Know Your Approvals questionnaire helps list which approvals a factory needs; confirm the timelines with each authority. Our note on the drawing set approvals need and the approvals roadmap show which drawing each file cites, which is why design freeze comes before submission.

How can the design period be shortened without cutting corners?

• Freeze inputs in writing before each stage starts, with a change log. Changes are allowed; unrecorded ones are what cost weeks.
• Use one design team for all four services. Electrical, HVAC, fire and plumbing designed by one team share one set of assumptions, one coordination model and one set of approval drawings.
• Release by package. Issue plant-room and substation drawings first, since those drive civil work and long-lead orders, and finish ceiling-level detail later.
• Order long-lead equipment from the concept load estimate only with a stated margin, and confirm ratings at vendor-drawing review. The MEPF cost calculator helps set budgets at that point.
• Run an independent design review before tender. A routing or rating problem found at drawing stage costs a revision; found on site, it costs rework.

How Secured Engineers helps

Secured Engineers designs electrical, HVAC, fire and plumbing in-house under one team, files the Fire NOC, CEIG and DISCOM applications in-house, and can carry MEPF and solar under one contract. The company works from offices in Noida (Delhi NCR) and Ludhiana and reports 535+ projects across 18+ states and 89.77% repeat clients. As a design consultant it can take a factory from basis of design to released drawings, or review another consultant's drawings before they go to tender.

If you have a layout and an equipment list, start from our design and approvals service, and send the drawings for a design review on WhatsApp or call +91 70099 85817. You can also ask for a free proposal.