Wall surfaces
Original render, or stucco on a Valleys terrace.
Early type houses were built entirely of stone, with cut stone arches over doors and windows. Later type houses were also built of stone, but for ease of building and because of the availability of the material, bricks were used to form door and window openings. Some later type houses were originally rendered, with decorative render surrounds at doors and windows.
As a general rule, changing the original wall surface to your house is unnecessary and can be detrimental not only to the character of the street but also to the way it performs. For example, applying a pebble-dash cement render to a stone fronted house destroys the rhythm of the street and can lead to damp problems by trapping moisture behind the render.
Where the mortar pointing on stone and brick houses is missing or weathered, dampness can become an issue but correct repointing using traditional mortar is often all that is required to overcome the problem.
Repointing
Repointing of brickwork and stonework.
Repointing of stonework and brickwork should only be undertaken where the mortar is very soft or loose or where mortar has weathered out, leaving open or deeply recessed joints vulnerable to water penetration. Where repointing is necessary, old pointing should be carefully raked out to a depth of between 25mm and 40mm, or at least to twice the height of the joint. Mortar should not be removed forcibly by the use of a mechanical disk or other methods that are likely to cause damage to arrises or to increase the width of joints.
The pointing mix should be compatible with the type and strength of the stones or bricks and suitable for the degree of weather exposure. Mixes will vary considerably according to circumstances but a rough guide is a proportion of approximately 1 : 3 of binding agent (such as a moderately hydraulic lime) to aggregate (a sharp sand, well washed and graded). Chimney stacks will require relatively stronger mixes.
The mortar should be packed firmly into the joint using a pointing iron after all loose material has been removed and the joint wetted to avoid the mortar drying out too quickly.
Pointing of old stonework and brickwork should have a neat flush or fractionally recessed joint and the mortar should not be spread beyond the joint on to the face of the stones or bricks. Modern forms of pointing such as ‘strap’, ‘ribbon’, ‘bucket-handle’ or ‘weather struck’, all of which are usually carried out in hard, cement rich mortars should be avoided because of the structural and material failures that can result.
Following the correct traditional procedures when repointing our stone-fronted terraces will overcome the need to apply alien coatings such as pebble-dash, stone cladding or spray-on ‘waterproofing’ sealants.
Brick and stone
Colour adds personality to your house and character to the street.
Bricks and stones should only be replaced where they have lost their structural integrity. This may be because of deep erosion, or serious fracture or spalling, or where weatherings are no longer performing the function of throwing water clear of the surfaces below. If erosion or spalling is only superficial it should be accepted, and loose, water-holding material carefully removed.
Replacement bricks should match the existing ones in dimensions, strength and durability, texture of finish, and colour. They should be laid in the same bond and width of joint. Matching second-hand bricks may be available and give an already weathered look.
Where possible, replacement stone should be local Pennant stone to match the original stone in size and colour. Cast stone or reconstructed stone is not recommended when replacing original stone.
If the stone or brick is badly soiled, simple washing with water, either by hand or with sprays, is recommended. Diluted hydro-fluoric acid, followed by a systematic neutralisation process, may be used to clean very badly soiled brickwork. Alkaline and other chemical cleaners should not be used as they contain soluble salts that tend to erode the wall surface. Industrial sandblasting is inappropriate. Only a skilled specialist contractor should carry out the cleaning of brickwork and stonework.
Smooth and Roughcast Render
Only houses that were originally rendered should be re-rendered. Flat and roughcast renders are intended to act as a protective outer layer to a building and periodically require repair or replacement. To function correctly, the render must be no stronger than the material to which it is applied. A weak mix allows the render to accommodate movement and to allow moisture to evaporate freely from the wall. Hard, cement-rich mixes should not be used as their lack of flexibility will cause them to crack, allowing water to penetrate and be trapped. The eventual result is the failure of the render.
If the existing render is believed to be original, it is recommended that it should be analysed so that the mix may be copied. It is also suggested that a sheltered area should be examined in order to determine the original colour and texture of the finish.
Hard, flat renderings should be avoided and pebbledash, spatterdash or Tyrolean finishes should not be used as these always appear modern.
The existing details at openings and corners should be followed. Non-traditional details such as bell drips, metal angles and stops should be avoided.
The render may be left uncoated, or be decorated with an appropriate lime based or other breathable finish. No impermeable paint system should be used, to avoid the risk of moisture entrapment.
Points to consider
If you have a satellite dish consider fixing it at the rear of your house to minimise the build up of ‘clutter’ on the front.
When fixing cables on the front of your house conceal them by locating them next to the rainwater pipes and gutters. Never run cables diagonally across the wall.
