How to Fix Flaking Paint on an Exterior Wall

interior painters adelaide flaking paint on an exterior wall is one of those problems that can quickly make an otherwise well-maintained home look tired. More importantly, simply brushing or rolling new paint over the damaged areas usually won’t solve the problem. If the old coating has lost adhesion, the new paint may fail along with it.

Exterior paint can flake because of moisture, weather exposure, poor surface preparation, chalking, mould, incompatible coatings or deterioration of the underlying surface. The correct repair therefore starts with finding out why the paint is failing, not just covering the visible flakes.

For Adelaide homes, exterior walls experience a combination of wet winter conditions and warm, dry summers. The Bureau of Meteorology describes Adelaide’s climate as Mediterranean, with most rainfall occurring between April and October.

Here’s how to assess and repair flaking exterior paint properly before applying a new finish.

Why Does Exterior Paint Start Flaking?

Flaking is generally a sign that the paint film has lost adhesion or flexibility.

The failure may occur between the paint and the wall, between different layers of paint, or between the coating and the underlying substrate.

Common causes include:

• Moisture entering behind the coating
• Poor surface preparation
• Painting over chalky or dusty surfaces
• Mould or moss
• Painting over loose previous coatings
• Applying paint in unsuitable weather conditions
• Inadequate priming
• Excessive paint thinning
• Deteriorating timber or masonry
• Incompatible coating systems

Resene’s paint problem-solving guidance identifies poor preparation, contaminants, chalking, mould and weathered substrates among the common causes of peeling and flaking. It also notes that very hot, cold or windy conditions can interfere with film formation.

That means the repair should not start with a paint roller. Start with an inspection.

Inspect the Wall Before Removing the Paint

Look at the affected area closely.

Is the paint flaking only in a few isolated spots, or is it failing across most of the wall?

Check for:

• Bubbling beneath the paint
• Cracks
• Powdery or chalky surfaces
• Damp patches
• Mould or moss
• Rust staining
• Rotten timber
• Failed sealant around windows
• Gaps around doors or other openings
• Areas where the substrate itself appears damaged

The pattern can provide useful clues.

For example, flaking around a window may require investigation of water entry or failed sealant. Flaking across an entire older wall may point towards widespread coating deterioration or poor preparation.

If moisture is getting behind the coating, repainting without addressing the source can simply result in another failure.

Remove All Loose and Flaking Paint

Once the cause has been addressed, the first major preparation step is removing paint that is no longer firmly attached.

Use a scraper or other appropriate mechanical method to remove loose material.

The objective isn’t necessarily to strip every layer of paint from the entire wall. The goal is to create a sound, stable surface.

Resene’s exterior preparation guidance recommends scraping away flaking paint and sanding back to a sound surface, with the remaining paint edges feathered.

How far should you scrape?

Continue removing paint until you reach a coating that is firmly adhered.

If paint can easily be lifted with a scraper, it should not be left underneath the new coating.

Where large areas are failing, more extensive removal may be necessary. Resene notes that badly deteriorated exterior coatings may require more extensive preparation, potentially including complete removal of the existing coating.

Wash the Exterior Surface Thoroughly

Exterior walls accumulate much more than visible dirt.

Over time, surfaces can collect:

• Dust
• Dirt
• Salt
• Mould
• Moss
• Surface chalk
• Cobwebs
• Atmospheric contaminants

These materials can interfere with adhesion.

Resene recommends treating moss and mould before washing, then cleaning exterior surfaces to remove dirt, residue, poorly adhered paint and chalkiness.

For a coastal Adelaide property, salt deposits can also be relevant. Resene’s exterior preparation guidance recommends rinsing surfaces with clean water to remove salt deposits, particularly for properties close to the sea.

Don’t assume that a pressure washer automatically provides adequate preparation. Cleaning needs to remove contaminants without damaging the substrate or forcing water into vulnerable areas.

Treat Mould and Moss Before Painting

If you see green growth, black spotting or other signs of mould or moss, deal with it before applying new paint.

Simply washing away visible growth may not be enough. Resene explains that residual mould spores can grow underneath a new coating and contribute to further flaking.

Use a suitable mould treatment according to the manufacturer’s directions, then clean and rinse the surface appropriately.

The wall should be allowed to dry thoroughly before further preparation.

If mould repeatedly returns in exactly the same location, investigate whether persistent moisture, poor drainage, leaking gutters or another source is contributing to the problem.

Sand the Edges of the Remaining Paint

After scraping, you may have areas where bare wall sits next to intact paint.

These edges should be feathered rather than left as sharp steps.

Sanding helps create a smoother transition between the old coating and exposed substrate. This is especially important if you want the finished wall to look uniform in different lighting conditions.

Resene specifically recommends sanding flaking areas to a feathered edge during exterior preparation.

Avoid aggressive sanding that damages the underlying substrate.

The objective is to remove loose material and smooth the transition, not unnecessarily remove sound material.

Repair Cracks, Gaps and Damaged Areas

Flaking paint can sometimes be associated with other surface defects.

Before priming, inspect the wall for cracks, holes and failed joints.

Small imperfections may be repaired with an exterior-grade filler or suitable sealant, depending on the substrate and size of the defect.

For cementitious surfaces, Resene’s guidance distinguishes between smaller cracks and larger cracks when selecting a suitable filling or sealing product.

Failed sealants around windows, doors and other joints should also be assessed rather than simply painted over.

If the substrate itself is damaged, repair that problem before continuing with the coating system.

Check for Chalking

A chalky exterior surface can look relatively intact but still cause problems for a new paint coating.

Run your hand across the surface. If a noticeable powdery residue transfers to your hand, the existing coating may be chalking.

Chalking needs to be removed or appropriately stabilised before repainting.

Resene’s guidance warns that painting over a weakly adhered or chalking coating can place additional stress on the existing system and contribute to further peeling.

This is one reason why simply pressure washing a wall and immediately applying a new topcoat may not be enough.

The surface needs to be clean, sound and suitable for the new coating.

Prime Bare Areas Before Applying Exterior Paint

Scraping away flaking paint often exposes bare substrate.

Those areas may need an appropriate primer or sealer before the exterior topcoat is applied.

The correct primer depends on what has been exposed.

Timber, masonry, metal and other substrates have different preparation requirements, so avoid assuming that one primer works for every exterior surface.

Resene’s exterior systems, for example, specify spot priming of exposed timber and other bare substrates before subsequent filling and topcoating.

Following the paint manufacturer’s recommended system is generally more reliable than mixing unrelated products without checking compatibility.

Choose the Right Exterior Paint for the Surface

Once the wall has been properly prepared, choose a coating designed for the particular exterior substrate.

The choice may differ depending on whether you’re painting:

• Render
• Cement sheet
• Concrete
• Timber weatherboards
• Masonry
• Metal
• Previously painted surfaces

Colour and sheen also matter.

Higher-sheen coatings can be easier to clean but may make surface imperfections more noticeable. Resene notes this trade-off in its exterior paint guidance.

For dark colours on sun-exposed surfaces, some manufacturers offer products or colour technologies designed to reduce heat absorption. The suitability depends on the specific coating system and substrate.

Consider Adelaide’s Climate When Repainting

Adelaide’s Mediterranean climate creates different challenges throughout the year.

The region generally experiences wet winters and warm to hot, dry summers, with most rainfall occurring from April to October.

That means exterior painting needs to account for both moisture and heat.

Avoid painting a damp surface simply because the weather looks clear. The substrate needs to be appropriately dry for the selected coating.

At the other extreme, very hot, windy conditions can cause paint to dry too quickly. Resene identifies excessive heat, cold and wind as conditions that can interfere with proper film formation.

Your paint manufacturer’s application instructions should take priority over a generic “best day to paint” rule.

Should You Pressure Wash a Flaking Wall?

Pressure washing can be useful for exterior preparation, but it needs to be used carefully.

A pressure washer can remove dirt and loose material, but excessive pressure can damage masonry, timber, render, sealants or other surfaces.

It also does not replace the need for scraping, sanding, mould treatment or priming.

For some substrates, particularly older or potentially fragile materials, a different preparation method may be more appropriate.

If the building contains suspected asbestos-containing fibre cement, do not treat it as a normal pressure-washing project. Resene’s guidance specifically warns against water blasting asbestos-containing cladding and roofing.

If you’re unsure about the substrate, have it identified before starting preparation.

When Should You Call a Professional?

DIY preparation can be suitable for a small, isolated patch of flaking paint on a straightforward surface.

Professional help becomes more sensible when:

• Large areas are flaking.
• The coating repeatedly fails after repainting.
• The wall is damp.
• Timber appears rotten.
• Masonry is deteriorating.
• There are significant cracks.
• Mould keeps returning.
• The building may contain asbestos materials.
• The existing coating is very old or difficult to identify.
• Extensive paint removal is required.

A professional painter can assess how much coating needs to be removed and determine which primer and exterior paint system is appropriate for the substrate.

Common Mistakes to Avoid

Painting over loose flakes

New paint cannot turn an unstable coating into a sound one.

Skipping the wash

Dirt, chalk, mould and salt can interfere with adhesion.

Leaving a sharp paint edge

Unfeathered edges can remain visible through the new coating.

Ignoring moisture

If water is entering behind the paint, the coating may continue to fail.

Using excessive pressure washing

Aggressive cleaning can damage the surface you’re trying to protect.

Painting before the surface is dry

Moisture can compromise the coating system.

Applying new paint in unsuitable weather

Very hot, cold or windy conditions can affect drying and film formation.

Using the same primer for every surface

Timber, masonry and metal may require different preparation systems.

Frequently Asked Questions

Why is the paint on my exterior wall flaking?

Common causes include poor surface preparation, moisture, chalking, mould, weathered substrates and loss of adhesion between coating layers.

Can I paint over flaking exterior paint?

No, loose and unstable paint should generally be removed first. The remaining sound coating should be prepared so the new paint has a stable surface to adhere to.

Do I need to remove all the old exterior paint?

Not always. If some existing paint is firmly adhered and in sound condition, it may be possible to prepare and repaint over it. Extensive coating failure may require more complete removal.

Should I pressure wash before repainting?

Pressure washing can help remove dirt and loose material, but it needs to be appropriate for the substrate. It does not replace scraping, sanding, mould treatment or other preparation.

Why does my exterior paint keep flaking after repainting?

Repeated failure can indicate unresolved moisture, poor preparation, chalking, incompatible coatings or unsuitable application conditions. The underlying cause should be identified rather than simply adding another coat.

How long should an exterior wall dry before painting?

There isn’t one universal drying period because it depends on the substrate, weather, humidity and product. Follow the specific paint manufacturer’s requirements and make sure the surface is suitably dry before coating.

Final Thoughts

Fixing flaking paint on an exterior wall is mainly a preparation job. The visible flakes are only the symptom; the underlying cause determines whether the repair will last.

Start by identifying moisture, mould, chalking or substrate problems. Remove all loose paint, clean the surface, feather the remaining edges, repair damaged areas and prime exposed substrate as required. Only then should the exterior topcoat be applied.

For Adelaide homes, choosing suitable painting conditions also matters because the climate brings both wet winter conditions and hot, dry periods.

If a large section of your exterior wall is flaking or the problem keeps returning, consider having the surface professionally assessed before repainting. A proper preparation plan can help prevent the new coating from failing along with the old one.