Zones & bands — MEP Tools
What each zone is for, the two structural bands, and how Linked zones works.
The five zones
| Zone | Holds | Notes |
|---|---|---|
| Zone D — Condensation-Risk Ducts | Standard HVAC ducts | A standard duct is flagged if it sits over Zone A's width |
| Zone E — Low-Condensation-Risk Ducts | Ducts flagged Low Condensation Risk Duct | May pass over Zone A |
| Zone A — Electrical Services | Cable trays | |
| Zone B — Access & Maintenance | Kept clear — this is the access corridor a technician stands in to reach the services around it | |
| Zone C — Piped Services | Pipes |
Two further bands appear in the section but aren't zones you place services in directly: the Structural Beam Band at the top of the void, and the Ceiling Device Drops Band at the bottom, reserved for vertical drops to fittings below the ceiling.
Turning a zone off
Each zone has an Enabled checkbox in its properties. Turning a zone off drops it from the drawing and from the coordination checks — but a zone that still holds services can't be disabled until you remove or move them out first.
Linked zones
Linked zones (on by default for a new document) keeps the zones attached edge to edge and filling the void: resizing one zone moves its neighbours so there's never a gap or an overlap. Turn it off in Project Settings to position each zone independently.
The access corridor (Zone B)
Zone B has to stay wide enough to work in, and it has to sit next to Zone A so the trays in it are reachable:
- Below the Zone B minimum width threshold (Tool Default: 600 mm), the corridor is flagged as too narrow to work in. At exactly the minimum it's flagged as a warning instead — there's no margin left for a later change to narrow it further.
- If Zone B doesn't share an edge with Zone A, every tray in Zone A is flagged as unreachable.
- A cable tray whose centreline sits further than the Arm's reach limit (Tool Default: 900 mm) from the nearest Zone B edge is flagged — it can only be reached by leaning into the void.
These thresholds are project-editable — see Rule set. The checks themselves are covered in full on Compliance checks.
Low Condensation Risk ducts
A duct flagged Low Condensation Risk Duct goes into Zone E instead of Zone D and is allowed to pass over Zone A's width — a standard duct is not, because it can shed condensate onto whatever sits below it. See Ducts, trays & pipes.