Ceiling Void Planner — Cheat Sheet
Quick-reference cheat sheet for the Ceiling Void Planner tool.
Published 27 May 2026
Ceiling Void Planner
Quick-reference companion for the free Portal tool
What This Tool Does
The Blind Solutions Architects Portal's Ceiling Void Planner is an essential tool for South African architects, engineers, and building services consultants. It helps in accurately calculating the required ceiling void depth to accommodate various building services (HVAC ducts, electrical conduits, plumbing pipes, fire suppression systems, and structural elements). This ensures compliance with SANS 10400-XA (Energy Usage in Buildings) by allowing for efficient service integration without compromising thermal performance or structural integrity.
Use this tool early in the design phase to prevent costly reworks, clashes, and delays. It's particularly crucial for projects involving suspended ceilings, intricate service layouts, or where ceiling height is a critical design or regulatory constraint, such as in high-rise commercial buildings in Sandton or residential developments in Cape Town.
Step-by-Step Usage Guide
Enter your project name (e.g., "Rosebank Office Block Phase 2") and select the closest major South African city. This helps tailor default climate zone considerations.
Specify the dimensions of primary structural elements crossing the void. This includes beam depths, waffle slab depths, or pre-stressed concrete members.
Input the largest dimensions of your main supply and return air ducts, including insulation thickness (typically 50mm for SANS 10400-XA compliance). Consider both rectangular and circular ducting.
Enter the maximum diameter for plumbing pipes (e.g., soil stacks), fire suppression mains, and electrical cable trays/conduits. Account for required clearances.
Specify the depth required for your chosen lighting fixtures (e.g., recessed downlights, linear fixtures) and the suspension system of the ceiling itself (e.g., grid system, plasterboard on furring channels).
The tool will provide a calculated minimum void depth. Review this and adjust standard clearances (e.g., 50mm between services, 100mm below structure) based on specific project requirements or contractor feedback.
Common Scenarios & Expected Results
| Scenario | Input | Expected Output |
|---|---|---|
| Standard Office Block (Johannesburg) |
Beam: 500mm, Slab: 200mm HVAC: 600x300mm + 50mm ins. Plumbing: 110mm, Fire: 80mm Electrical Tray: 100mm Lighting: 120mm, Ceiling: 50mm |
~850mm - 950mm (depending on service overlap and clearances) |
| Luxury Apartment (Cape Town) |
Beam: 400mm, Slab: 180mm HVAC: 400x200mm + 25mm ins. (smaller units) Plumbing: 75mm, Fire: 50mm (sprinkler lines) Electrical Conduits: 50mm Lighting: 100mm, Ceiling: 40mm |
~600mm - 700mm |
| Retail Space (Durban) |
Waffle Slab: 450mm (overall depth) HVAC: 1000x500mm + 50mm ins. (large open plan) Plumbing: 160mm (stormwater), Fire: 150mm Electrical Tray: 200mm Lighting: 200mm (feature lights), Ceiling: 75mm |
~1100mm - 1300mm |