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Painting Exterior Walls: The Ultimate Guide and How-to 

There are few DIY projects that have as great an impact on the look of your home as a fresh coat of paint on your exterior walls. Well-applied, quality paintwork can truly transform your home, increase its value and give added protection from weather damage.

Painting the exterior of your home can be a daunting task, but with the right tools, time, energy and good planning, it can be achieved at a fraction of the cost of hiring a professional.

As usual, the secret to a successful finish is good preparation. Make sure you have the necessary equipment and products for the job before getting started. It is really worth doing this job well because, depending on conditions, a properly applied coat of quality exterior paint can last up to 15 years.

Good quality, waterproof, dirt-resistant, exterior masonry paint is available to buy in a smooth or finely textured finish and there are now a wide array of colours to choose from.

A home improvement project like this is a great opportunity to personalise your home or garage to suit your style. Small paint testers can be useful in choosing the right colour for you. Textured paints have silica sand added and are particularly suited to uneven surfaces and can help hide small cracks or flaws while providing additional durability.

Handy Tip: Check the forecast. Rain is not the painter’s friend. Walls need to be dry before you paint and you will need enough time for the new coat to dry properly before the next expected downpour is due.

How Do You Prepare An Exterior Wall for Painting?

Power washing is a great way to prepare exterior walls for painting. Removing dust, cobwebs, flaking paint and dirt leaves a clean, even surface for the paint to bond to. This means a longer life for your exterior paint. Power washing should ideally be carried out on a mild sunny day. This is also a good opportunity to clean out gutters and wash fascia and soffit.

You’ll also need to inspect your exterior walls for any irregularities or flaws in need of attention before painting. Evidence of mould, fungal growth or efflorescence will need to be addressed in advance of painting. Hairline cracks or signs of unstable surface, ie flaking or crumbling paint will also need to be remedied beforehand.

Ensure you have sufficient drop clothes, dust sheets, tarp or other material to protect the surrounding areas, to avoid spills and splashes on your patio or pavings. Protect any doors and windows with dust sheets or big sheets of cardboard affixed with masking tape.

Move items that could obstruct access to the wall, away from the area and ensure you can reposition the ladder as required or erect a scaffolding platform if needed.

Safety Tip: Use a sturdy ladder that allows you to paint the highest point on the exterior wall without stretching more than arm’s length. If using an extendable ladder, remember that three rungs should overlap for safety.

Do You Need To Seal Exterior Walls Before Painting?

In short, yes, most exterior masonry surfaces need to be sealed before painting. If the wall is porous, chalky and badly weathered applying a stabilising solution is recommended.

You can check your exterior masonry walls for signs of an unstable surface with the touch test. If you rub the wall with your palm and it comes away dusty or if the wall feels chalky or powdery to the touch this indicates an unstable surface. You can also scrape away flaking paint to reveal if there is a powdery residue underneath. If you paint directly onto an unstable, friable substrate, be that spalled and crumbling brickwork or badly weathered cement rendering, the paint will bond to the dust and debris rather than the wall and will begin to come off with it.

You will need to seal the wall with a stabilising solution, this is a highly penetrative primer formulated for binding chalky powdery surfaces. The good news is this stabilising sealer will make the surface less absorbent and porous so will require less paint.

Common Issues To Bear In Mind

Before painting inspect exterior masonry walls carefully to identify these common issues

Mould or fungal growth. This type of contamination on the surface or substrate of your exterior walls will need to be treated carefully with a fungicidal wash before applying paint. If you skip this step, the staining will eventually come through the new coat of paint and continue to grow, potentially damaging the substrate further.

For best results remove as much of the growth as possible with a stiff brush or scraper before applying the fungicidal solution. Leave for 24 hours, rinse thoroughly and allow the exterior wall to fully dry before painting. Safety Tip: Follow the manufacturer’s instructions carefully, wear protective clothing while applying the fungicide and contact your local council to safely dispose of leftover product.

Moss or Lichens. These can naturally occur in especially damp conditions on exterior walls and can grow quite quickly. However, they are easy to remove with a brush or scraper and an application of moss and lichen remover will prevent them from re-growing.

Efflorescence. This fine white powder can be found on both brickwork and cement rendering and is caused by moisture evaporating from the surface leaving salt minerals behind.

It can be a simply remedied cosmetic issue or it can indicate a more serious problem with moisture intrusion. A moisture metre can help identify the cause.

Differentiating efflorescence from white mould is straightforward – of the two, only efflorescence dissolves in water. A stiff brush can be used to remove the salty residue from brickwork.

Hairline cracks and holes. These can be filled with fine surface masonry filler. You can buy these ready-mixed for wall repairs or make your own cement-based filler with sand, cement and water mixed to a stiff paste.

Prepare the area by scraping out loose debris, spraying with clean water, then using a filling knife apply filler to the dampened substrate. ‘Wetting in’ deep cracks and holes helps the filler to adhere better.

If it’s a deep crack, more than 10mm, you will need to build up filler in stages, allowing each stage to dry before applying the next. Fill until slightly proud of the surface, level with a wet filling knife, and when thoroughly dry sand down and apply alkali resistant primer.

Can You Paint Over Old Exterior Masonry Paint?

Once all surface issues from dirt to cracks to fungal growth have been addressed and you have a clean stable substrate to work with you can apply a new coat of paint over old exterior masonry paint.

How To Paint Exterior Walls

Once you have your exterior walls washed, prepped and ready to go follow these steps to get a perfect finish:

Step 1: Tool Up

Make sure you have all the right tools and equipment at hand:

  • Masonry Paint
  • Masonry Paint Brush (This large firm long bristled brush holds more paint)
  • Small brush for ‘cutting in’ to edges and corners
  • Paint Roller (Long pile, ¾ to 1″ – especially for rough surfaces like pebbledash)
  • Extension pole for the roller
  • Roller tray or 10l bucket with roller screen
  • Drop Cloths, Cardboard and tape for masking
  • Sturdy ladder or scaffolding platform
  • PPE e.g. Overalls, gloves, eye protection and dust mask (for cleaning safely)

Step 2: Masking off

Masking off is a really important step to ensure a clean finish and to protect your doors, windows and other features from getting paint on them. Take your time to apply tape carefully to all frames, you will be glad you did. You can also cover windows with cardboard at this point to protect them from splash.

Masking tape will tape down protective window covering whilst allowing you to paint a perfectly straight line.

Step 3: Cutting in

Using a small brush gives you much better control when cutting in around gutters, windows and door frames. A 3-inch paintbrush is a good tool for this job.

Step 4: Get Rolling

Working from top to bottom, roll paint on in sections. Starting from the top allows you to remedy drips as you work downwards, giving a great even finish.

Painting Tip: Applying pressure on the upward stroke of the roller with a lighter pressure on the way back down helps to avoid splashback.

Using a roller will allow you to cover a large surface area quicker than a brush would.

Step 5: Allow to dry

Your exterior wall paint will benefit from having a full 24 hour drying period before the next rainfall. This is why planning with the weather in mind is essential

Step 6: Tidy Up

Remove the masking tape from door and window frames, wash and dry brushes, rollers and paint trays and store for next time. Contact your local council to find out how to dispose of any hazardous or leftover materials safely in your area.

Step 7: Enjoy

Take a moment to appreciate the fruits of your labour.

Final Thoughts

Painting your exterior masonry walls can be far more challenging than, say painting your dining room. It comes with its own unique challenges and issues to bear in mind.

It can be easy to underestimate the labour involved and the amount of time and stamina it takes to paint exterior walls. But there are few home improvement projects as rewarding, and with a little preparation and planning, seeing your freshly painted exterior walls looking fantastic will make it all seem worth the effort!