External walls are the outer shell of a building. They provide thermal insulation, protect a building and its inhabitants from the elements, and support the weight of the upper floors.

Cavity walls are commonly used as external walls. This is a wall made from two separate walls with a space (cavity) in between which is usually filled with insulation).

Common materials for external walls

Brick

Used for its timeless appearance. Durable and long lasting, bricks are highly fire resistant, relatively lightweight, and easy to handle/transport. Bricks are also reusable and recyclable. However, bricks are porous and do allow water to pass through. They are not as strong as other materials, such as stone, and can be hard to clean properly.

Concrete

Used for its strength and durability, concrete is low maintenance and cost effective. Concrete also has a relatively low carbon footprint. However, when not reinforced, concrete is low in tensile strength and flexibility. It is also relatively heavy when compared to its strength.

Timber

Used for its high levels of thermal insulation, timber is easy to work with and has a relatively low environmental impact compared to other materials. However, it is highly combustible unless it has undergone fire rated treatment and, if not treated properly, can mould.  

Metal cladding

Cladding is the application of one material to another, providing a degree of thermal insulation and weather resistance. It is low maintenance when compared to other materials, easy to install and durable. However, it can rust or fade.