How To Repaint Exterior Brickwork
External painting season is quickly approaching, with warmer drier weather becoming the norm we would like to share our technical expertise in getting your external brickwork looking as good as new. There are numerous factors to consider when starting any outdoor painting project, but with our tips and advice you can ensure a professional finish everytime. Shop everything you need to paint exterior brickwork at The Paint Shed today.
This may seem obvious but if you are planning to paint your exterior brick walls it is best to do so in Summer, for the sole reason that you will need a few days of no precipitation for the paint to dry and properly hold. If you are painting on the original clay and mortar clocks of an exterior brick wall there are a few other things to consider.
Factors to consider
The moisture content of the wall - Excessive moisture will affect the adhesion of the most paints and can lead to blistering and flaking, as well as encouraging the growth of mould and algae. Allow the wall to substantially dry out (typically 4-6 weeks) before painting.
Efflorescence - As moisture leaves the brickwork a crystalline deposit may form on the surface of your wall. Remove the deposit with a broom and treat the brick work with a salt treatment like Everbuild’s Salt-Away cleaner. Allow to dry before applying any paint.
Alkalinity - If you are painting with solvent based paints they could be affected by the alkali present in the moisture contained within your bricks. Alkalinity will diminish over time but with newer brickwork an alkali resistant primer should be used. Shop our wide selection of primers here.
Porosity - Bricks vary considerably in porosity and absorption. The more open and porous brick types would require that you thin the first application of primer or paint according to brands instructions.
Staining - When using water based paints the iron oxide in the brickwork may bleed through causing rust straining, to prevent this happening prep your surface with a stain blocking, rust preventing primer.
Exterior brickwork has special needs and requirements, in general If your exterior walls have not been painted previously then it is best to seek expert advice, as ‘sealing’ brickwork with paint may not be an appropriate procedure for certain types of brickwork and may be detrimental to brick function.
Once painted however, exterior walls need to be maintained. This is a job that requires good planning and a substantial amount of preparation work to ensure the finish will be long-lasting and have a professional appearance. Here is how to prime, prepare and paint pre-painted exterior walls.
Essential tools and preparation advice
First scrub loose debris, dust and flaking paint using a brush or broom. Then wash down with a detergent solution to remove dirt, grease etc. If using a power-washer be careful not to get too close or linger too long in any particular area as this can damage the brickwork, mortar or woodwork. Any areas affected by mould, lichens, algae and moss should be treated with a fungicidal wash. Rinse with clean water and allow to dry completely.
Then carefully scrape off any flakes or defective coatings, sand down to key and feather edges of existing paintwork. Avoid using a wire brush as some of the wire may break off and become embed in the surface – this can rust if water-based masonry paint is applied. Repair minor defects with an appropriate masonry filler, allow to cure for one week.
New or bare surfaces should be sealed with a thinned first coat of appropriate masonry paint to ensure adhesion of the finishing coats. Primer can be used on those surfaces that are powdery or chalky after preparation. Avoid using a ‘stabilizing primer’ on new or bare surfaces. Protect your floor and nearby furnishings from paint splashes with a drop cloth or old bed sheets.
Good quality masonry paints are specially formulated to help let the walls breathe. If you apply a glossy sealer then any moisture passing through the paint will condense on the sealer causing the masonry paint to blister or flake. Get advice from the experts at The Paint Shed on which are the most appropriate exterior paints to use – some finishes even come with a 15 year guarantee. They can also advise you on the best method of application (particular brushes or rollers) which can be dependent on which paint is used. Whatever paint you choose, two or three coats is recommended for a uniform finish, allow 30 minutes dry time between each coat.
The inside of metal gutters can be coated with a layer of an appropriate bitumen-based paint for additional protection. The outside of metal gutters, the brackets and downpipes can be painted with exterior undercoat and gloss. Use a wire brush to remove any loose rust and flaking paint. Abrasive paper can then be used to smooth out rough areas. Metal surfaces should be smooth to the touch and needs a primer to 'key' the surface. This will allow the topcoat to be applied evenly and smoothly. All newly exposed metal requires a coat quick-drying metal primer.
Plastic gutters and downpipes are normally best left unpainted but if they have discoloured then you can apply 2 coats of gloss paint directly onto the cleaned plastic. Primers and undercoats are not necessary.
For more guides on exterior and interior painting look to your tips and advice blog.