Weathered brickwork can add character to a house and it is a pity to allow stains to spoil its appearance. You can treat small areas of brickwork yourself, although large areas are best left to a contractor suitably equipped and qualified to do job. Each types of stain needs specific treatment and the wrong cleaning method can make it look worse and cause permanent damage. If you are planning to clean brickwork yourself, therefore, it is important to establish what caused the stain and to know what type of brick you are dealing with.

Clay is the most widely used material for bricks and is produced in a variety of textures and sand facings. Calcium silicate bricks, which are smooth surfaced and white or off-white in their natural state, can be tinted to almost any colour and textured by sand-blasting or acid-etching.

Causes of Staining – In most cases staining on brickwork is caused by external deposits which discolour the face of the bricks. Occasionally, however, the trouble may be caused by salts in the bricks, known as efflorescence, is common in  new brickwork and is dispersed by wind and rain. In old brickwork it is caused by excessively wet conditions. Unless the problem of water penetration is cured, the salts will keep reappearing. Vegetable growth on bricks is encouraged by moisture which may be due to faulty flashings, perforated damp proof courses or more often, leaking downpipes or gutters. In such cases, cure the cause of the damp before tackling the stain.

Cleaning it yourself – Water plays an important part in any brick cleaning operation, especially where chemical cleaners are used. Saturate both clay and calcium silicate brickwork with water before applying the cleaner and rinse thoroughly afterwards. Brick can become damaged by abrasion, so use a wood scraper or stiff fibre brush where possible.

If natural calcium silicate brickwork is badly stained, you may find cleaning leaves a patchy surface. To give a uniform appearance you can either rub down the whole surface or apply a decorative coating such as an alkali resistant paint to hide the patches.
Warning Many of the cleaning chemical recommended are either caustic or poisonous, so always wear goggles and protective clothing when using them. Any volatile solvents used for cleaning internal brickwork should also be used with care and, if working inside, the room should be well ventilated. Protect surrounding features which might be adversely affected by cleaners.