External walls may be of brick or block, stone, render, wood or pre-fabricated panels. Often, they are made of more than one material - such as masonry lined with wood, rendered or pebble-dashed.

 New walls and walls built since the introduction of cavities (two layers of brick with an airspace between) should have insulation between the layers of brick (cavity wall insulation). Alternatives to cavity construction include modern timber-framing with infill panels.

The external walls need to carry the weight of the roof and any upper storeys. In a conversion, it may not be possible to salvage the original walls if they are in very poor condition.

On a conservation project, we will work with existing materials, and will reclaim and re-use original masonry when possible.

If an old wall is structurally sound it can be repaired and replastered. Wiring and piping is laid before the wall is plastered. Dry lining a wall with insulated plasterboard gives extra insulation. It can be applied to many types of existing wall and all new walls.

Interior walls often have a wooden framework which supports plasterboard. Structural internal walls (those which play a role in supporting the building) are masonry, like external walls.