---
title: "Cladding fixed to a structural backing"
subject: "Building Technology"
chapter: 9
key: "semester_6/building_technology:cladding-structural-backing"
source: https://www.bctengineer.com/q/semester_6/building_technology/cladding-structural-backing
site: BCT Engineering
---

# Cladding fixed to a structural backing

Building Technology · Chapter 9: Finishing works

- Asked in: 2081 Chaitra, 3 marks
- Video: [How to Install Matrix™ Cladding – Tools, Components, Design Considerations and Installation Process](https://www.youtube.com/watch?v=Tb5eQSjZFCQ) — JamesHardieAu
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/cladding-structural-backing
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-9

## Question

Critically explain cladding fixed to a structural backing.

## Short answer

Cladding is a non-load-bearing skin fixed to a structural wall for protection and aesthetics. It can be bonded with adhesive, anchored with metal cramps, or hung on battens. Movement joints are needed; differential movement and moisture can cause cracks and corrosion of fixings.

## Answer

**Cladding** is a non-load-bearing covering or skin of material (stone, tile, brick, timber, metal, glass, GRC, etc.) fixed to the face of a wall or frame, either inside or outside, to protect it and to improve its appearance.

#### Cladding fixed to a structural backing
Here the cladding is fixed directly to a structural wall or frame (the backing), which carries its load. The backing may be a brick, block, concrete or steel wall.

**Methods of fixing:**
- **Adhesion (bonded):** thin tiles or slabs bonded to the backing with mortar or adhesive, over a rough plaster. Used for tiles and thin stone.
- **Mechanical fixing:** stone slabs are fixed by metal cramps, dowels, or anchors to the backing, leaving a cavity of 25-50 mm filled with grout or kept open.
- **Hung on battens or rails:** timber or metal battens are fixed to the backing, and boards or tiles hung from them.

```text
  Stone slab fixed to backing
  backing wall | 25-50 mm gap | slab
  wall |==cramp==|[ stone slab ]
  wall |  dowel  |[ stone slab ]
```

**Merits:** good support, a secure fix, lower cost, less space.
**Critical points / demerits:**
- Differential movement between cladding and backing (due to temperature and moisture) can crack the cladding or cause failure.
- Movement joints are needed every 3-6 m.
- Moisture trapped behind the cladding can cause efflorescence and corrosion of fixings.
- Fixings should be of stainless steel or brass.
- Heavy slabs need strong anchors and the backing must be sound and dry.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. In cladding fixed to a structural backing, what carries the load?
   A. Nothing
   B. The cladding alone
   C. The backing wall or frame
   D. The paint
   Answer: C. The backing carries the cladding's load. (Key point: Structural backing)

2. What is a key critical point?
   A. No fixings needed
   B. It cannot be fixed
   C. Cladding is too light
   D. Differential movement between cladding and backing can crack the cladding
   Answer: D. Temperature and moisture differences cause movement, so movement joints every 3-6 m are needed. (Key point: Differential movement)

3. What material should fixings be?
   A. Stainless steel or brass
   B. Iron nails
   C. Wood
   D. Mild steel
   Answer: A. Trapped moisture corrodes ordinary steel. (Key point: Fixings)

## Related in other subjects

- [Generate stiffness matrix of frame](https://www.bctengineer.com/question.md?key=semester_5%2Ftheory_of_structures_ii%3Astiffness-matrix-frame-coordinates-123) — Theory of Structures II, chapter 3