MEP Works

Coordinating the services before anything is fixed

Electrical, plumbing and low-current services share ceiling voids, risers and wall cavities with ductwork and the finishing trades. On a well-run job they are drawn together on one coordination set before first-fix. A useful order of priority: gravity drainage takes its route first, because its falls cannot be adjusted; then large items such as ducts; then pipework; then cable trays and containment; and small conduit and low-current cabling fit around them. Maintenance access and the space the ceiling system needs are checked on the same drawing. Anything that will need servicing later, such as isolating valves, junction boxes and pull boxes, should land where an access panel can reach it.

Penetrations need the same care. Sleeves and openings through slabs, beams and walls should be located and approved before concrete is poured or plaster goes on, and any penetration through a fire-rated wall or floor must be sealed as the specification and Saudi Civil Defense requirements demand. The finishing at Drug Control Department Tower was coordinated with active MEP works, the situation where this discipline pays for itself.

The four MEP trades: what each delivers and needs

Scope and BOQ: builder's work, boundaries and testing

The commonest MEP gaps sit at the boundary with other packages. Name these before pricing:

• Builder's work: chasing, sleeves, plinths and making good, and who bears the cost of returning after first-fix.
• Which systems are in this scope and which are separate packages, such as HVAC, fire alarm and firefighting, lifts and building management.
• Fixture, luminaire and equipment schedules, and who chooses and supplies them; late changes move rough-ins.
• Temporary and permanent power and water for testing and commissioning, and who arranges the utility connections.
• Testing: what is tested, when, in whose presence, and where the record is kept.
• Labelling, as-built drawings and operation documents required at handover.
• Spare capacity: spare ways in distribution boards, spare containment space and spare data points, stated in the documents rather than assumed.

Climate and ground: what changes for MEP by region

The trades do not change with the city, but the conditions they work in do.

• Jeddah: humidity and salt air corrode metal containment, enclosures and fixings, especially outdoors and in plant rooms, so specify corrosion-resistant finishes and suitable enclosure protection in exposed locations. Cold pipework can also sweat in humid air, so its insulation and sealing need attention.
• Riyadh and Al Kharj: dry heat and dust. High temperatures in ceiling voids and roof spaces reduce what a cable can safely carry, so sizing must allow for them, and dust calls for suitably protected enclosures and equipment.
• Dammam: coastal humidity and salt much like Jeddah's, plus a shallow water table and salty ground that can be aggressive to buried pipework and manholes, so confirm pipe material and protection for anything below ground.
• Al Ahsa: inland desert conditions closer to Riyadh, so the same heat and dust points apply.

Hold points before MEP work is buried

MEP work is buried, so it is inspected before it disappears, and each check should leave a written record:

1. Coordination drawings: approved and issued before first-fix starts, showing the ceiling void and riser sections.
2. Sleeves and penetrations: checked against those drawings before slabs and walls close; the record shows location and size.
3. Pipework: pressure test witnessed and recorded before chasing or screed, showing which line, the result and who signed.
4. Circuits and cables: test results recorded for each circuit or cable before ceilings close, with fire-stopping in place at penetrations.
5. Fixtures and devices: positions checked against the approved layout before tiling and paint.
6. Commissioning: each system shown working to the client or consultant, with camera views and data points verified.
7. Handover: labelled boards and outlets, as-built drawings that match what is behind the wall, and any manuals the contract requires.

One MEP team or separate specialists?

Electrical, plumbing, CCTV and networking share containment, risers and ceiling voids, so running them under one team removes most clashes and leaves one party to ask about any wall or ceiling. Systems outside these four trades, such as HVAC, fire alarm and firefighting, lifts and building management, are normally separate packages. The risk sits at the boundary, so write down who provides what at each connection point, such as power to a camera or a drain to an air-conditioning unit. See Supervision & Consultancy for how coordination meetings and query logs are run.