Cladding fixed to a structural backing

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.

  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.