There is more to the walls of your house than first meets the eye. It is important to know what type of walls you have if, for example, you need to drill through them or make repairs. This guide to wall construction will show you the different types of wall you might find in your house. You can learn how to build walls with our guides to Building a Wall and Building a Stud Wall.
Almost all external walls are load-bearing, so any major alterations need to be planned carefully. Putting in a new doorway, for example, will require the wall to be propped.
Solid walls are usually as thick as length of one standard brick (or 225mm). On buildings over 2 storeys, the lower walls might be “brick and a half” or 345mm thick. This is to take the larger load of the storeys above. Solid walls are usually found on older houses rather than new. One of the main problems of a solid wall is that it offers less protection from the elements. Water can seep through the wall and penetrate the house more easily than with Cavity Walls.
A cavity wall is made up of two separate “leaves” with a small (50mm) gap between. Each of the two leaves will usually be only the thickness of one brick (about 100mm). In modern houses, lightweight concrete blocks will probably make up the inner leaf as they are far cheaper and more heat-efficient than bricks. The two leaves are held together by wall ties to increase strength. Cavity walls in general offer much better insulation as water cannot so easily seep through and the air pocket acts as an additional insulation layer. Additionally, cavity wall insulation material can be injected/placed into the cavity.
Drilling Cavity Walls
If you ever need to drill through one or both leaves of a cavity wall, you need to be careful to avoid debris falling into the cavity as much as possible. This could build up on a wall tie and form a bridge for moisture to travel through the cavity and into the inner leaf.
If you live in a very old house, your walls could be made of Cob. You can usually tell by the thickness of the wall, which could be a couple of feet thick. Traditionally Cob was a mixture of clay sub soil mixed with straw and sometimes dung (the dung and straw helped to stop cracking during the drying process). Cob walls are built up in layers, with each layer being allowed to dry before the next it added. Cob walls are amazingly durable as long as moisture is not allowed to accumulate. Modern render, gypsum plaster and paint can stop Cob drying out after wet weather, allowing moisture to build up, often with disastrous consequences. Be aware that any house old enough to have Cob walls will probably be listed or in some way protected. Any alterations may require extra permissions from your local authority.
Internal walls can be a mix of load-bearing and non load-bearing. It can often be difficult to tell the difference. Plasterboard (stud) or lathe and plaster walls will be non load-bearing, whilst a solid wall which runs through the middle of the house, parallel to the floorboard could well be load-bearing. If in doubt, seek professional advice.
Partition walls are almost always (certainly in modern houses anyway) constructed as a frame of timber (studwork) covered by plasterboard and plaster. Older houses may well have the same basic construction, only with lath’s (thin strips of wood nailed to the studwork) replacing the plasterboard. The hollow in the middle will usually carry cables, etc, for the lighting system. Partition walls can usually be removed or have doorways cut into them without effecting the stability of the house.
Solid Internal Walls
As with external solid walls, this will probably be 225mm thick if it is a load-bearing wall, or 100mm thick if it not carrying any weight. Sometimes internal walls will be constructed of cement blocks instead of the more expensive bricks. A framework of wooden battens will usually then cover internal walls, with plasterboard nailed over the top (dry lining).