Cladding of Buildings

Description

The term ‘cladding’ refers to components that are attached to the primary structure of a building to form non-structural, external surfaces. This is as opposed to buildings in which the external surfaces are formed by structural elements, such as masonry walls, or applied surfaces such as render.

Building Safety Fund for the remediation of non-ACM Cladding Systems (England only) Registration prospectus, published by MHCLG in May 2020 suggests that: ‘A cladding system includes the components that are attached to the primary structure of a building to form a non-structural external surface. The cladding system includes the weather-exposed outer layer or ‘screen, fillers. Insulation, membranes, brackets, cavity barriers, flashing, fixings, gaskets and sealants.’

Whilst cladding is generally attached to the structure of the building, it typically does not contribute to its stability. However, cladding does play a structural role, transferring wind loads, impact loads, snow loads and its own self-weight back to the structural framework.

In particular, wind causes positive and negative pressure on the surface of buildings and cladding must have sufficient strength and stiffness to resist this load, both in terms of the type of cladding selected and its connections back to the structure.

Cladding is needed to:

• Create a controlled internal environment.
• Protect the building from external conditions.
• Provide privacy and security.
• Prevent the transmission of sound.
• Provide thermal insulation.
• Create an external facade.
• Prevent the spread of fire.
• Generate an ‘airtight’ building envelope.
• Providing openings for access, daylight and ventilation.
• Cladding is often prefabricated in panels that are attached to the structural frame of the building, and some cladding systems can be purchased ‘off the shelf’.

Cladding systems may include additional components, such as windows, doors, gutters, roof lights, vents and so on.

The nature of cladding selected for a particular building will depend on considerations such as:

• How the building is going to be used.
• Internal and external conditions.
• Durability.
• Local context.
• Planning requirements.
• Building regulations requirements.
• Accessibility and buildability.
• Appearance.
• Availability.
• Budget.
• Maintenance requirements.
• Structural requirements.
• High-quality, well-designed, properly-installed cladding can help maximise thermal performance, minimise air leakage, and optimise natural daylighting. This can help reduce the need for mechanical and electrical building services, and so improve energy efficiency and lower capital and running costs.

Poor design detailing or installation may compromise cladding performance and can result in safety problems such as cladding collapse or cladding panels pulling away from the structure.

When selecting or designing a suitable cladding, designers should pay particular attention to:

• Design detailing.
• Control of air leakage.
• Control of condensation.
• Integrity and continuity of Insulation.
• Prevention of water penetration, or provision of drainage.
• Control of thermal movement.
• Spread of fire.
• Ease of installation.
• External attachments and fixings.
• Cleaning.
• Maintenance, remedial work and renewal.
• Resilience, strength and durability.