# Grid False Ceiling Calculator: Tiles, Tees and Wall Angle

> A grid false ceiling is built from main tees hung from the slab, cross tees clipped between them to form a grid, a wall angle around the edge, and lay-in tiles. For a 600 × 600 mm grid the quantity of each part follows directly from the ceiling area and perimeter.

## What it calculates

For a rectangular room with a 600 × 600 mm lay-in grid ceiling, the calculator gives the
quantity of each component:

- **ceiling tiles**, 600 × 600 mm;
- **main tees**, in the lengths supplied;
- **1200 mm cross tees** and **600 mm cross tees**;
- **wall angle**, in the lengths supplied;
- **hangers** with their fixings.

## Inputs

**Room length** and **room width** are the inside dimensions in feet.

The **assumptions** panel holds the wastage on tiles and sections, the main tee and wall angle
lengths as supplied, and the hanger spacing along the main tees.

## Method

The grid geometry fixes the quantities for each square metre of ceiling:

| Component | Spacing | Quantity |
| --- | --- | --- |
| Tiles | 600 × 600 mm | area ÷ 0.36 m² |
| Main tees | 1200 mm centres | area ÷ 1.2 = running metres |
| 1200 mm cross tees | 600 mm centres between main tees | area ÷ 0.72 m² |
| 600 mm cross tees | One across the middle of each 1200 × 600 panel | area ÷ 0.72 m² |
| Wall angle | Around the edge | perimeter, in running metres |
| Hangers | Along each main tee at the chosen spacing | area ÷ (1.2 × spacing) |

Running lengths are divided by the length supplied and rounded up; counts are rounded up.
The wastage allowance is applied to tiles, tees and wall angle.

## Assumptions

| Assumption | Default | Notes |
| --- | --- | --- |
| Grid | 600 × 600 mm | Main tees at 1200 mm centres |
| Wastage | 5% | Border cuts and breakage |
| Main tee length | 3.6 m | Check the supplier's length |
| Wall angle length | 3.0 m | Check the supplier's length |
| Hanger spacing | 1.2 m | Follow the manufacturer's installation guide |

## Limitations

- **Rectangular rooms only.** Split other shapes into rectangles; small and irregular
  areas need more wastage.
- **The grid is not set out.** Where the grid starts decides the size of the border tiles;
  a designer centres it so border tiles are not thin slivers.
- **Services are not included.** Light fittings, diffusers, grilles, access panels and
  sprinklers replace tiles and may need extra cross tees and independent supports.
- **Hangers depend on the structure.** The hanger type and fixing depend on the slab or
  roof above and on the height of the drop.
- **No bulkheads or level changes.** Steps in the ceiling need framing outside the grid.

## Worked example

A 30 ft × 20 ft room (9.14 m × 6.10 m) with a 600 × 600 mm grid, at the default assumptions:

| Component | Calculation | Quantity |
| --- | --- | --- |
| Ceiling area | 9.14 × 6.10 | 55.74 m² |
| Perimeter | 2 × (9.14 + 6.10) | 30.48 m |
| Tiles | 55.74 / 0.36 × 1.05 | 163 |
| Main tees, 3.6 m | 55.74 / 1.2 × 1.05 / 3.6 | 14 |
| 1200 mm cross tees | 55.74 / 0.72 × 1.05 | 82 |
| 600 mm cross tees | 55.74 / 0.72 × 1.05 | 82 |
| Wall angle, 3.0 m | 30.48 × 1.05 / 3.0 | 11 |
| Hangers | 55.74 / (1.2 × 1.2) | 39 |

In practice some tile positions will be taken by light fittings and diffusers. Those
positions still need the grid, so the tees stay the same while the tile count falls.

## How engineers use it

An interior designer or site engineer starts from the reflected ceiling plan, which shows the
grid set-out, the lights, diffusers, sprinklers, detectors and access panels. The grid is
coordinated with all of them before ordering, and the quantity take-off is done room by room
from that drawing. The geometry in this calculator is the same; the drawing adds the real
shapes, the services and the border sizes.

## When a professional design must replace it

Use the calculator to estimate materials for a room or check a supplier's quantities.
Replace it with a reflected ceiling plan coordinated with the lighting, HVAC and fire services
before the ceiling is ordered or installed. Where the ceiling has fire, acoustic or
humidity requirements, the tile and grid system is selected and specified by the designer.

## Frequently asked questions

### How is a 600 × 600 grid ceiling laid out?

Main tees run in one direction at 1200 mm centres and are hung from the slab. 1200 mm cross tees clip between the main tees at 600 mm centres, making 1200 × 600 mm panels. A 600 mm cross tee across the middle of each panel splits it into two 600 × 600 mm squares, which take the tiles. A wall angle supports the edges.

### Why are the 1200 and 600 cross tee counts the same?

In a 600 × 600 grid, every 1200 × 600 mm panel formed by two main tees and two 1200 cross tees has one 600 cross tee across its middle. So there is one of each for every 0.72 m² of ceiling, and the counts match before rounding.

### How far apart should the hangers be?

Follow the ceiling manufacturer's installation guide for the system and the loads it carries. The calculator starts with one hanger every 1.2 m along each main tee and lets you change it. Light fittings, diffusers and other services in the ceiling often need their own independent supports.

### Does this include gypsum ceilings?

No. A gypsum board ceiling uses a different metal framing system and screwed boards, not a lay-in grid, so its quantities follow different rules. This calculator is for 600 × 600 mm lay-in grid ceilings with mineral fibre, metal or similar tiles.

### How much wastage should I allow?

Border tiles are cut to fit the edges, and the off-cuts are rarely reusable. Large, regular rooms waste little; small rooms, corridors and rooms with many columns waste more. The calculator starts at 5% on tiles and sections; raise it for small or irregular spaces.

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Source: https://hagerstone.com/calculators/grid-ceiling-calculator