What shop drawings are, and what they are not
Tender or IFC design drawings show intent: duct and pipe routes in single line, equipment schedules, riser diagrams and load calculations. Shop drawings are the contractor's response. They show real sizes after selecting actual equipment, double-line ducts with insulation thickness, pipe sizes with fittings, hanger and support positions, access panel locations, sleeve and opening sizes, and exact levels referenced to finished floor or structural slab.
A shop drawing is not a redesign. Where the contractor proposes a change, such as a different chiller footprint, a re-routed main or a revised riser arrangement, it should be flagged clearly with a clouded revision and a short technical justification. Silent deviations are one of the fastest ways to get a submittal returned, and they cause disputes later when the as-built drawings no longer match the approved basis.
- Floor-by-floor layouts per trade: HVAC, drainage, water supply, firefighting, electrical containment and lighting, ELV
- Plant room and riser details at larger scale with sections
- Roof layouts showing chillers, cooling towers or condensing units with service clearances
- Equipment connection details, valve arrangements and pump sets
- Calculation reports updated for selected equipment: heat load check, ESP, pump head, voltage drop, hydraulic calc
Combined services drawings (CSD) and why they decide the ceiling height
A combined services drawing overlays all MEP trades with structure and architecture: beams, drop panels, post-tensioned slab tendons, ceiling grid, bulkheads and light fittings. Its job is to prove that everything fits within the ceiling void and riser with the clearances needed to install, insulate and maintain it. In residential towers with tight floor-to-floor heights, the CSD is usually where the real ceiling level is fixed.
Good coordination follows a priority order. Gravity drainage gets first claim because it cannot rise, then large ducts, then sprinkler mains and chilled-water pipes, then cable trays, and finally small-bore services that can bend around. Sections are cut at every congested point, typically corridors outside lift lobbies, riser exits and plant room entries, and every crossing shows a level.
Builder's work drawings: openings, sleeves and plinths
Builder's work in connection (BWIC) drawings tell the civil team where to leave openings in slabs and walls, where to cast sleeves, and where to build plinths, kerbs and access hatches. On post-tensioned slabs the timing is critical: openings must be agreed before tendon layout is frozen, because coring later through a tendon zone is often prohibited or needs structural approval.
Fire-rated walls and slabs add a second layer. Every penetration through a compartment boundary needs a listed firestopping detail, and duct penetrations need fire dampers or rated enclosures as the design requires. Showing these on the BWIC and CSD avoids the familiar civil defence inspection failure where a sleeve is in the right place but the gap around it cannot be sealed with an approved system.
- Slab openings and core-drill positions with sizes and references to gridlines
- Wall openings and sleeves, including those in fire-rated walls
- Equipment plinths with anti-vibration mounting allowances
- Access panels for valves, dampers, VAV boxes and cleanouts
- Roof upstands and pipe or duct penetrations with waterproofing detail
Clash detection and BIM: what it adds in practice
On larger projects the coordination is done in a federated 3D model where each trade models its services and software runs automated clash tests. The value is not the clash count; it is the structured meeting where clashes are grouped, assigned and closed. Hard clashes such as a duct through a beam are obvious; the more useful checks are clearance clashes, for example a valve with no room for a hand or a fan coil unit with no space to drop the filter.
BIM does not replace site knowledge. Models are only as good as the inputs: actual equipment dimensions, insulation thicknesses, hanger sizes and the real installation sequence. Where a project works in 2D, the same discipline can be applied with layered CAD overlays and carefully cut sections. The output either way is a signed-off CSD that the foreman can install from.
The submittal and approval cycle
Each drawing package is submitted to the consultant with a transmittal, revision number and reference to the related material submittals. The consultant returns it with a status, commonly Approved, Approved as Noted, Revise and Resubmit, or Rejected. Only the first two allow work to proceed, and comments on an Approved as Noted return must be incorporated in the next revision.
Material submittals should run ahead of or alongside shop drawings, because a layout drawn around a chiller or pump that is later rejected must be redrawn. The main contractor coordinates the overall register, while authority approvals for fire systems and utility connections run in parallel through the relevant civil defence and utility channels, such as DEWA in Dubai, SEWA in Sharjah or ADDC in Abu Dhabi.
- Drawings that do not reflect approved materials or equipment
- Missing sections at congested zones or unclear levels
- Inadequate maintenance access or service clearances
- Deviation from design without clouding or justification
- Unresolved clashes with structure or other trades
- Incomplete firestopping or fire damper locations
How Manolia approaches shop drawings
Engineering and shop drawings are stage four of Manolia's eight-stage delivery process, sitting after planning and before procurement so that what is ordered matches what has been coordinated. The group has carried shop drawings and coordination through towers up to 50+ floors, including Al Salam Tower in Sharjah with 52 typical floors, where getting the first typical floor right pays back on every floor above it.
Document control under a QMS structured to ISO 9001 requirements keeps revisions, transmittals and consultant comments traceable from first submittal to as-built, which matters most at handover when the final drawings must reflect what was actually installed.
Frequently asked questions
Who prepares MEP shop drawings on a UAE project?
The MEP subcontractor normally prepares shop drawings for its own trades, while the main contractor or a nominated coordinator manages the combined services drawings and overall submittal register. The MEP consultant reviews and returns them with a status. On design and build packages the contractor also carries design responsibility, so the drawings must be backed by calculations.
Can work start before shop drawings are approved?
Generally no. Contracts usually allow installation only from drawings returned as Approved or Approved as Noted. Some early works such as sleeves in slabs may be released on the basis of an approved BWIC drawing before full layouts are complete, but starting from unapproved layouts risks rework at the contractor's own cost.
Is BIM mandatory for MEP coordination?
It depends on the employer's requirements and the project size. Many larger developments in Dubai and Abu Dhabi specify a BIM execution plan and federated model, while smaller buildings are still coordinated in 2D CAD with overlays and sections. The obligation comes from the contract, so check the employer's requirements at tender stage.
What usually delays shop drawing approval?
The most common causes are material submittals not yet approved, repeated resubmissions because earlier comments were not closed, late architectural changes to ceilings or layouts, and missing structural information such as post-tensioned tendon drawings. Holding regular coordination meetings with the consultant and tracking each comment to closure reduces the number of cycles.
What is the difference between shop drawings and as-built drawings?
Shop drawings show what is planned to be installed and are approved before work. As-built drawings record what was actually installed, including any site changes, and are submitted at handover with the O and M manuals. Facility managers rely on as-builts for maintenance and future modifications, so they must be accurate and complete.