Masonry paint and preparation

Masonry paint, unlike emulsion paint, is especially formulated to give a long-lasting, external all weather protection. Its flexible, resists flaking and is suitable for exterior application on roughcast, concrete, stock, facing bricks, and/cement rendering, pebbledash – so don’t be tempted to save money and use anything else, it’ll end up costing you time and money, sooner than you think. By doing the job properly and using the best paint you can afford, you’ll probably not have to repaint the outside of your house for the next 15 to 20 years (this assumes normal conditions).

Before you paint, ensure the surface is clean, sound and free from mould. What you use to achieve this state is dependent on the present wall surface. A stiff brush or an anti-fungal wash, should do the job but if its bad, you may have to use a light power wash – but be careful and let the wall dry out fully, before applying paint.

Once you have a good, clean, dry surface, you should patch test the wall (see below). If you are painting more than one wall or the whole house and garage, patch test each wall separately – don’t assume they’ll be all the same.

New surfaces: All surfaces should be clean, sound, clean and dry. Free from anything that will interfere with the adhesion of the paint. Patch test and stabilise the surface as required.

Uncoated surfaces: As with ‘new surfaces’, all surfaces must be sound, dry and free from anything that will interfere with the adhesion of the paint. You must remove all organic growth by scraping or brushing with a stiff, none wire, brush. Established growth may need to be removed by pressure washing but be careful not to damage the underlying surface or force water through joins. If it is really bad, you may have to consider wet or dry grit blasting. When this is done, treat the surface with a fungicidal wash. Allow to dry and fill any cracks. Patch test and stabilise the surface as required.

Previously decorated surfaces: As with ‘new surfaces’, all surfaces must be sound, dry and free from anything that will interfere with the adhesion of the paint. Loose or failing paint must be removed. Washing the surface with a liquid detergent or a sugar soap solution will remove contaminants and improve paint adhesion. Any glossy or eggshell paint surfaces must be abraded to provide a key. Any organic growth must be removed by scraping or brushing with a stiff, none wire, brush.

Established growth may need to be removed by pressure washing but be careful not to damage the underlying surface or force water through joins. When this is done, treat the surface with a fungicidal wash. Allow to dry and fill any cracks. Patch test and stabilise the surface as required.