Cladding is the application of one material over another to provide a skin or layer. In construction, cladding is used to provide a degree of thermal insulation and

weather resistance Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement), ...

, and to improve the appearance of buildings. Cladding can be made of any of a wide range of materials including wood, metal, brick, vinyl, and composite materials that can include aluminium, wood, blends of cement and recycled

polystyrene Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is a ...

, wheat/rice straw fibres. Rainscreen cladding is a form of weather cladding designed to protect against the elements, but also offers thermal insulation. The cladding does not itself need to be waterproof, merely a control element: it may serve only to direct water or wind safely away in order to control run-off and prevent its infiltration into the building structure. Cladding may also be a control element for noise, either entering or escaping. Cladding can become a fire risk by design or material.

Description

Cladding in construction is material applied over another to provide a skin or layer and used to provide a degree of thermal insulation and

, and to improve the appearance of buildings. Between the cladding and the wall there is a cavity where rain can run down.

Design

Materials

Cladding can be made of any of a wide range of materials including wood, metal, brick, vinyl, and composite materials that can include aluminium, wood, blends of cement and recycled

, or wheat/rice straw fibres. Materials used for cladding affect vulnerability to fire.

Purposes

Rainscreen cladding is a form of weather cladding designed to protect against the elements, but also offers thermal insulation. The cladding does not need, itself, to be waterproof, merely a control element: it may serve only to direct water or wind safely away in order to control run-off and prevent its infiltration into the building structure. Single-skin metal panels are pre-formed wall panels made from metal that are one of the most commonly available types of cladding for industrial and commercial projects. Their high durability and easy installation make them ideal for low maintenance builds. Cladding may also be a control element for noise, either entering or escaping. Cladding applied to windows is often referred to as

window capping In construction, capping or window capping (window cladding, window wrapping) refers to the application of aluminum or vinyl sheeting cut and formed with a brake to fit over the exterior, wood trim of a building. The aluminum is intended to make a ...

and is a specialized field.

Vulnerability to building fires

Tower block with cladding exposed in Sheffield 2017

Between the cladding and the wall there is a cavity where rain can run down. In the event of a fire this draws hot air up like a

chimney A chimney is an architectural ventilation structure made of masonry, clay or metal that isolates hot toxic exhaust gases or smoke produced by a boiler, stove, furnace, incinerator, or fireplace from human living areas. Chimneys are typic ...

, intensifies the fire, and spreads it to the top of the clad area. The fire can then get inside the building through open windows, for example to curtains blowing through windows. In addition to the chimney effect, the cladding material itself can contribute to a fire. Brick has excellent fire resistance; planks or weatherboards made from fibre cement or steel have high fire resistance; aluminium and reconstituted timber products have good fire resistance, and timber weatherboards and

plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured ...

sheets have poor fire resistance. Composite cladding typically consists of panels thick made of a core material sandwiched between two aluminium faces. The core material may be polyethylene (which is combustible), a mineral-based material, or a combination of both. Panels of the same appearance may have different core materials; those with a higher proportion of mineral core withstand fire better, but can still be considered combustible. Fire will be spread ''by'' the cladding if the core is combustible. In the wake of the

Grenfell Tower fire On 14 June 2017, a high-rise fire broke out in the 24-storey Grenfell Tower block of flats in North Kensington, West London, at 00:54 BST and burned for 60 hours. 72 people died, two later in hospital, with more than 70 injured and 223 escapin ...

in London, and similar fires in France, Dubai, and elsewhere, great attention has been paid to the fire protection qualities of cladding used in tower-blocks and similar high-rise multiple-occupancy housing and, in particular, the use of aluminium composite material (ACM) and ACM panels (ACP). Grenfell Tower was clad with composite panels with a polyethylene core which contributed to the fire; these panels cost about £2 less than ones with incombustible core. There are estimated to be about 600 high-rise blocks of flats in the UK that have "similar" cladding and some fire safety tests—not full

BS 8414 BS 8414 is a 2002 British Standard British Standards (BS) are the standards produced by the BSI Group which is incorporated under a royal charter and which is formally designated as the national standards body (NSB) for the UK. The BSI Group pro ...

tests—were carried out on panels; of the first 75 tested, 100% failed. Updated as information becomes available.

References