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Preparation is key

When decorating exteriors, it is important to plan the project to ensure that you achieve the best results.
It is important to understand that paint will only perform well with the correct surface preparation.
Using the correct preparation products and application tools can make the job easier and result in a longer lasting, more aesthetically pleasing finish. Understanding why we paint exterior masonry, the two key motivations and drivers are protection and decoration.
Protection is achieved by the paint creating a barrier against not only moisture and wind but also the adverse effects of UV rays from the sun that can damage exterior surfaces.

Top Tip: Observe the next day’s weather forecast prior to starting a large exterior paint project.

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Look at the property prior to painting, what are you looking for?

  • Old flaking or blistering paint
  • Worn or damaged surfaces
  • Cracks
  • Damp and fungal growth
  • Unstable chalky surfaces
  • Consider access to out of reach areas and the need for ladders or towers
  • What protection is required e.g. dustsheets, masking tape etc
  • It is important to choose a suitable day as exterior painting in especially cold weather (below 8°c) or extremely hot weather creates its own challenges with paint not drying or indeed drying too quickly.

Top Tip: For best results paint in daylight if possible

Removing old paint

Complete all stripping and rubbing down before you start painting so that dust and flakes will not fall on wet surfaces. Start from the top and work down, clean out gutters and paint if necessary.

When removing old flaking masonry paint, use a scraper where possible then for small flakes a stiff bristle brush which will remove residual flakes. It is important NOT to use a wire brush on the masonry surfaces as metal particles can become embedded on the surface, these react to the water based masonry paint thus resulting in potential rust spots that will make the walls look unsightly. When removing old paint it is recommended that you wear safety goggles / glasses, gloves and a mask, this will reduce the risk of damaging your eyes or breathing in dust particles.

Organic mould growth

Often you can encounter a problem with mould growth on an exterior wall, it is important to effectively treat these contaminated areas as the mould will come through newly painted areas. Where there is a particular mould issue, initially remove any surface contamination with a scraper then use a stiff bristle brush. Once the surface is sound you must apply a fungicide solution, these should be diluted with water and you must always follow the pack instructions. As they are usually a bleach based material, for safety, use gloves and goggles or safety glasses.

Apply the fungicide solution to the affected area plus an overlap to ensure the solution penetrates the surface and kills the organic growth. Again check the manufacturer’s pack instructions as to the recommended time prior to painting over the fungicide solution, this is usually 24 hours. This will ensure a clean surface for a better adhesion of the masonry paint.
Mould tends to grow in damp conditions so it is important to deal with not just the mould problem but also the cause of the problem as this could be a leaking gutter or concentrating water on the wall, creating a damp area.

Top Tip: For best results paint in daylight if possible

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Unstable surfaces

One of the problems that can occur when painting an exterior wall is a chalky and dusty unstable surface. If you apply paint without effectively treating this problem the paint will dry and stick to the loose dust particles and not get a sound adhesion to the wall resulting in the paint blistering and failing.
To check for this issue wipe your hand on the surface to be painted and if you have dusty particles on your hand then you will require a stabilising solution. The stabilising solution is very easy to apply using a 3” brush direct to the surface, allowing it to dry for 24 hours prior to painting. The stabilising solution seals, and stabilises the surface to allow for good adhesion of the masonry paint, it also allows the paint to cover further.

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