What is backing timber?
Backing timber is a wooden batten, rail or framework installed behind wall cladding, panelling or linings to provide a substrate for fixing the facing material. The backing timber forms the framework onto which boards, panels or sheets are screwed or nailed.
Function
Backing timber serves several purposes:
- Fixing substrate — provides a solid base for attaching cladding, wall panels or linings
- Levelling — irregularities in the wall or structure behind are taken up by packing or shimming the battens to form a true plane
- Ventilation — the backing timber creates a cavity between the cladding and the substrate, allowing air to circulate and moisture to drain away
Application
Backing timber is used in many areas of construction:
- External cladding — vertical or horizontal battens onto which weatherboards, shiplap or fibre cement panels are fixed
- Internal walls — timber battens behind plasterboard or tongue-and-groove panelling
- Ceilings — battens from which ceiling boards or panels are suspended
- Roof sarking — battens on rafters onto which roof boarding is nailed
Material and sizes
| Application | Typical size (mm) |
|---|---|
| Internal wall lining | 25 × 50 or 38 × 50 |
| External cladding | 25 × 50 or 38 × 63 |
| Ceiling | 25 × 50 or 38 × 38 |
For external applications, pressure-treated timber or Accoya is used. Centres are typically 400 to 600 mm, depending on the cladding specification.
Related terms
- Cladding
- Batten
- Timber
- Sub-frame
- Weatherboard
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