Last edited 09 Oct 2019

Exterior wall

1 Introduction
2 Materials
3 Construction systems used to build exterior walls
4 Related articles on Designing Buildings Wiki

[edit] Introduction

An exterior wall typically forms part of the building envelope and so separates the accommodation inside from that outside. Its main function is to provide:

Environmental control – mediating between indoor and outdoor climates.
Weathering – providing resistance to the weather determines durability and appearance.
Security – although this will also depend on window and door openings.
Fire control – preventing fire spread either on the wall surface or in its cavities.
Aesthetics – along with the roof, determines to a large extent the external appearance of the building.

In loadbearing construction such as masonry, the exterior wall may also provide support to the combined dead, imposed and wind loads of the roof and floor construction and convey them to the foundations. This is in addition to the wall’s own combined loads.

In a framed structure, the external walls are usually non-loadbearing and are therefore relieved of any upper floor and roof loadings. However, they are normally self-supporting and are designed to resist wind loads, prevent the spread of fire and accommodate thermal movements.

[edit] Materials

Exterior walls can be made of a wide variety of materials either singly or in combination with other materials. These can include:

Masonry laid in courses with mortar (loadbearing or facings)
Concrete
Timber
Metal cladding – requires a framework for support
Glass, metal or timber panels
GRP/GRC cladding.
Terracotta.

[edit] Construction systems used to build exterior walls

Various construction systems can be used to build an external wall, including:

Loadbearing – using bricks and blocks, or reinforced concrete. Timber is used for log cabin construction. Exterior walls form part of the structure.
Framed – the exterior wall can be located around the structure, inside (thereby exposing the structure) or as infill panels located within the depth of the frame itself. Irrespective of the plane it is in, the exterior wall in these situations is usually referred to as ‘cladding’. These types of exterior wall wrap around the building’s structure, are typically non-loadbearing and serve as an aesthetic and climatic component. Tied back to the structure with ties, they can be made of facing bricks, concrete blocks, timber panels, glass, plastic and other lightweight materials. Accommodating thermal movements is usually required if long, uninterrupted wall lengths are involved.
Rainscreen – a thin façade made of metal, terracotta or other panel type is attached to a lightweight frame which is itself bolted to the building structure. In appearance, it is not usually possible to tell that the result is a façade of relatively little thickness. There is usually a ventilation gap between the back of the facing panel and the face (or inner wall) of the building. Rainscreens provide an opportunity to retrofit insulation to existing buildings.