The walls and ceilings of a house are some of its most important structural elements, but also offer considerable scope for creativity. This article will help you understand the structure of ceilings and walls so that you can work out which options are most suitable when undertaking repair or renovation work.
Types of Construction
A knowledge of how ceilings and walls are put together is important to fully understand the structure of your home. In the most general terms, ceilings usually have a wood-frame structure. Walls are either cavity or single-skin, and may be loadbearing or non-loadbearing. In addition, there is a variety of ways that ceilings and walls may be finished, and there are different combinations of materials that can be used to achieve these finishes.
The illustrations opposite demonstrate the basic structures of frame and concrete ceilings. Beneath these are shown the typical finishes used on their lower surfaces. Frame ceilings are traditional but still widely used. A framework of frame joists provides support for the floor above, and a surface for attachment of the ceiling finish below. Concrete ceilings can take a variety of forms. They are more often found in modern buildings, and their popularity has grown with the general use of concrete in the building industry.
Insulation and Finishes
A wide range of materials can be used in finishing either a ceiling or wall — drywall can vary in thickness and density, and can also be purchased with useful retardant properties to make the surface more resilient, or to adhere to building and safety regulations. Insulation is not shown in the illustrations here or overleaf, for reasons of clarity. However, in reality, many ceilings and walls will incorporate insulation.
Understanding Beams and Joists
Beams and joists are not the same — beams support joists. Traditionally, they are made of wood, but modern types are often made of steel, and are known as “I-beams.” Rolled steel joists are also available. Wooden beams are often left uncovered to form part of a room’s decorative aspect, although they can be clad with plasterboard and then plastered. Old beams may even be found beneath lath and plaster.
I-beams are usually boxed in with drywall and then finished. To provide securing points for drywall, blocking (small vertical lengths of wood) is installed inside an I-beam. Lintels and headers look similar to beams, but perform a different function: they support the weight of a wall above an opening such as a window or door. They come in many materials and strengths, designed for a variety of uses.
Boxing In a Beam
Beams are frequently enclosed and hidden behind a finish, but a little knowledge of basic house construction should allow you to locate them. A traditional method of boxing in is shown here, but it is also possible to use insulating panels and clips. Ceilings are usually installed flush with the lower surface of the beams.
Frame Ceiling and Finishes
The type of wood and dimensions of joists will depend on the size of the ceiling and its function — ceilings with a floor above must be more substantial. Blocking at right angles to the joists can connect them to increase rigidity.