Modular OR Process Step 3: Design, Engineering & Drawing Approval

Published Oct 25, 2026 · Operating-Room.com Editorial Team

Introduction

Once the purchase order is released, the project moves from consulting into engineering. A dedicated project manager is assigned — MECART makes this single point of contact the rule "throughout the entire project" — and the survey data, room schedule and clinical requirements become a fully coordinated design. The engineering phase ends with client-approved detailed drawings, because those same drawings drive the factory's numerical cutting machines. There is no later, informal chance to move a door or a gas outlet.

Layout and Functional Zoning

The first drawing set is architectural: floor plans, reflected ceiling plans and elevations that organise the suite around contamination control. A typical design distinguishes four zones:

Restricted zone — the operating room itself and its sterile core, fed by a laminar-flow ceiling over the surgical field.
Semi-restricted zone — clean corridors, sterile storage and scrub areas, entered through changing rooms.
Unrestricted zone — staff and patient access, reception and pre-op areas.
Contaminated routes — independent soiled corridors and waste holding, kept physically separate from clean supply paths.

Eucalyptus designs the same principle into IVF laboratories: a clean corridor leads through shoe-changing, dress-changing and an air shower into the embryology, andrology and cryopreservation areas, with "the shortest path connecting key functional areas" and pass boxes used where materials must cross boundaries without people. General surgery suites add switchable room layouts, reserved equipment interfaces and pre-assembled equipment mounts so one room can serve multiple procedure types.

HVAC, Pressurisation and Cleanliness Engineering

The mechanical design is where an OR suite earns its ISO classification. Engineers calculate air-change rates, filter stages and room pressure gradients to achieve the contracted cleanliness classes — for example ISO 8 support rooms up to ISO 5 over the operating table, or ISO Class 6/7/8 across an IVF laboratory. Typical elements:

Three- or four-stage filtration terminating in HEPA supply, with laminar-flow diffuser ceilings in the sterile zone.
Cascading positive pressure from the cleanest room outward, with real-time differential-pressure monitoring between zones.
Galvanized-steel ductwork selected for air tightness, plus activated-carbon sections where odor and VOC removal matter.
Temperature and humidity control to the program set points (22–25 °C and 40–60% RH in IVF labs), with dedicated supply and return paths so neighbouring rooms cannot disturb stability.

Panel Design and the Wall–Ceiling System

The enclosure is engineered as a kit of parts. Each wall and ceiling panel is drawn individually, with its openings, returns and embedded services. A representative specification, from Eucalyptus's theatre panel system, shows the construction the drawings must define:

Front face: 1.2 mm anti-fingerprint electrolytic galvanized steel sheet.
Core: hydrophobic rock wool between double-layer glass-MgO boards for fire resistance (rated at ≥ 1 hour) and acoustic performance.
Back face: color-coated steel sheet, sealed inside a perimeter galvanized-steel stud frame.
Jointing: precise panel-to-panel connections, internal and external corner pieces, wall-to-ceiling transitions and ceiling carrier rails, with rounded (coved) internal corners for hygienic cleaning.

Because mechanical and electrical utilities, hatches, door leaves, view windows and embedded cabinets are wired into the panel cavity at the factory, their positions are fixed on these drawings — which is why MECART feeds approved files straight to its laser cutters: "no errors in the positioning of utilities and hatches" are possible once geometry is machine-driven.

BIM Coordination and Interfaces

Modern modular OR design is coordinated in 3D. The panel model is clash-checked against ductwork, medical-gas lines, pendant and light structures, operating-table anchors, electrical containment and the integrated OR control system — the LCD multi-function controllers, automatic sensor doors with foot activation and anti-pinch protection, medical-gas alarms and nurse-call interfaces seen in delivered projects. The model also defines the contractor boundary points confirmed at survey: power, water, gases, exhaust and data.

The Approval Gate

MECART's plan-review cycle is typical of the industry: a detailed engineering plan is submitted, the client returns comments, revisions are issued, and the cycle ends in formal drawing approval. Hospital teams should review at minimum: room dimensions and door swings, gas and power outlet schedules, light and pendant positions, airflow/pressure diagrams, finish colors, fire-rated penetrations and the equipment interface matrix. Signed approval converts the design into manufacturing drawings; after that point, changes mean remanufactured panels, not redlines.

Conclusion

Design engineering is the last chance to solve problems on paper, where it is cheapest. Approve a fully coordinated, clash-checked set — zoning, HVAC, panel shop drawings and interfaces — and the factory receives geometry it can cut without interpretation. With the drawings frozen, production begins, which is step 4.

Previous: Step 2 — Site Survey & Field Measurement · Next: Step 4 — Factory Prefabrication. Sources: MECART — Engineering and Design; Eucalyptus — Modular OT Wall & Ceiling Panel System; Eucalyptus — Modular General Surgery OR.