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Repairing External Walls of an Older Home

Knowing how your walls are constructed is a good starting point for effective repair. This page highlights the common types of material used and the problems they may face.

A bad case of brick decay
Damp walls can often cause bricks to deteriorate

Traditional wall construction

Most houses of traditional construction are built with brick or stone, or a combination of the two. Some of our earliest houses used timber framing, which was often a cheaper - and in some areas a more readily available - alternative to masonry.

If you want to make repairs to the walls of your home you may need to get permission and should seek advice. This is especially important if your home is listed or in a conservation area (see Who Do I Contact?).

Solid brick walls

Bricks were originally made by hand using local clays and sands. The later machine-made ones are more even in shape and colour.

Brick walls may need repairs for a wide variety of reasons. These include:

  • Structural issues, where movement can cause bricks to fracture.
  • Crumbling of very soft or under-fired bricks over time.
  • Damp walls. Bricks become saturated, and are then damaged through freeze/thaw action, or where salts come to the surface and cause flaking and decay.
  • Use of inappropriate mortars.

Cavity walls

Cavity walls can suffer from many of the same problems as solid brick walls. The original 'hollow walls' were developed to provide as much protection from the elements as possible. Consisting of two separate leaves of brickwork with space between them, held in place with metal ‘ties’, they became known as cavity walls.

Older cavity walls are particularly susceptible to structural stability issues, as early wall ties were not galvanised so they tend to rust and lose their ability to hold the two leaves of brickwork together.

Steps to take

If cracks are appearing in your walls seek advice from a structural engineer. When treating damp, make sure you are addressing the problem as well as the symptoms. Check for issues such as blocked gutters, damaged flashing or whether a damp course has been bridged.

If you need to make repairs to old brick walls it's best to seek advice from a professional with experience of older buildings. Most repairs are likely to entail some repointing, or possibly the removal and replacement of some of the bricks. It's rare that a whole wall will need to be rebuilt.

Make sure you use appropriate materials (see Using the right materials for more information) to repair your building.

Matching new and existing bricks is important when carrying out repairs, not only for the visual effect, but also to ensure they will weather in a similar way. Although there are far fewer brick companies around today many of the locally produced bricks are still available. 

Close-up of a crack in a stone wall
Structural issues can cause walls to fracture

Stone walls

Stone suffers from many of the same decay problems as brick. There are two types of preparation for stone used in housebuilding: rough uncut 'rubble' stone; and dressed cut 'ashlar' stone. Often the two were combined, with rubble stone used for the wall core and ashlar stone used for the facings.

Steps to take

If cracks are appearing seek advice from a structural engineer. If you need to make repairs to old stone it's best to get advice from a professional with experience of older buildings. Try to match new stone with the existing material to make sure that repairs don't affect the appearance of your home. 

Stone for building was very much a locally sourced material before national transport systems were developed. This gives certain areas of the country a particular character – e.g. the honey-coloured villages of Cotswold stone.

Timber framing

Rot is probably the most significant repair issue for timber-framed houses. Walls were made of prefabricated timber frames, which were infilled with a daub mixture onto a wattle framework backing. Later these panels were often replaced with brickwork, and sometimes the whole frame was rendered with a lime render and limewash.

Excessive moisture in the timber joints can ultimately lead to structural issues if not dealt with at an early stage. The infill panels are also vulnerable to damp.

Steps to take

If your house is suffering from damp or rotting timbers you should seek advice from a specialist with experience of older buildings. As well as damp, the timber may need to be treated for biological problems such as fungus or woodworm. Timbers or parts of timbers may need to be strengthened or, as a last resort, replaced. 

Check and fix anything that is causing or exacerbating damp - a cracked drainpipe, an overflowing drain, lack of ventilation. It's important to use appropriate materials in any repair (see Using the right materials for more information). If modern impervious materials such as cement-based fillings or impermeable coatings are used in repairs the timbers will decay even faster.

The timber frame method of house construction has existed for centuries. Timber was often a cheaper alternative to masonry and in certain parts of the country more readily available. Timber-framed houses are often slightly crooked as a result of movement over the years. This does not automatically mean that the house is about to fall down, and such crookedness can contribute much to a building's character.

Crooked timbered building
Timber-framed buildings often experience distortion and movement

Earth walls

All forms of earth walling are susceptible to water penetration, particularly when exposed to severe weather. They were often plastered with a protective coating of lime render. If the render is not maintained the wall itself becomes very vulnerable to decay.

Steps to take

If your walls are damp check rainwater goods and flashings to make sure that you've addressed the problems as well as the symptoms. Seek advice from a professional with experience of earth walls in your area. 

Earth walls are a lot less common than the other forms and are found predominantly in rural areas. The method has a variety of regional names: cob, mud, clay dabbins, rammed earth, wychert. Clay lump and chalk lump are similar techniques in which earth or chalk is made into unburnt blocks that are laid in clay-based or lime mortars.

It's important to use the appropriate materials (see Using the right materials for more information). If you use modern impervious materials it will only cause more damage as any moisture gets locked in.

Render and stucco

External renders and stucco are susceptible to cracking, allowing damp into the backing wall. The maintenance of these materials can be quite onerous. 

External renders have been in use for hundreds of years. Early forms were usually lime-based mixes applied as a two- or three-part coating, and were often used to cover timber frames. Later, in the 18th and 19th centuries, they were used to make brickwork look like stone. Pebbledash, also known as roughcast, is a form of stucco that incorporates gravel.

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