When a roof coating system fails, it leaves your home’s structure vulnerable to substrate degradation and internal water damage. Identifying the specific cause of delamination is the only way to ensure the next application provides a lasting 10-year protection cycle
Why Roof Paint Fails?
Roof paint peeling, also known as delamination, occurs when the coating loses its grip on the tile or metal surface. This is primarily caused by painting over dirt or moisture, skipping a compatible roof primer, or using low-grade paint that cannot handle Australian UV levels. To fix it, you must remove all failing material, treat the underlying cause (like rust or moisture), and apply a high-adhesion primer system such as Oz Primer.
1. Surface Contamination and Poor Cleaning
Paint cannot bond to a surface covered in dirt, algae, moss, or old flaking residue. Dirt and organic growth act as a physical barrier, preventing the liquid coating from reaching the pores of the tile or the grain of the metal. If you apply a new topcoat over these contaminants, the paint will eventually bubble and lift away.
The Solution:
Thoroughly clean the roof using a high-pressure washer to remove all loose debris and organic matter. If moss or lichen was present, a chemical treatment may be necessary to kill remaining spores. Allow the roof to dry completely before applying any primer, as trapped moisture under the paint will cause immediate adhesion failure.
2. Skipping or Using the Wrong Roof Primer
Skipping a primer is the most frequent cause of premature peeling on porous concrete tiles and smooth metal sheets. Aged concrete tiles are highly porous and absorb moisture, which causes standard paint to delaminate if the surface isn't sealed first. On metal roofs, the surface is often too smooth for topcoats to grip without a dedicated bonding agent.
The Solution:
Match your primer to your roof material. Use Oz Primer or Platinum Primer for concrete tiles to seal the pores and create a stable foundation. For metal roofs, use Metal Primer Plus to ensure a strong chemical bond. Primers act as the essential "middleman" that ensures the topcoat remains attached during thermal expansion and contraction.
3. Trapped Moisture and Substrate Porosity
Porous materials like concrete tiles and wood absorb water from the air and the ground. If paint is applied while the substrate is damp, or if the primer fails to seal the pores, the sun’s heat will turn that trapped moisture into vapour. This internal pressure forces the paint film upward, creating bubbles that eventually crack and peel.
The Solution:
Ensure the substrate is dry and use a high-build primer system designed for Australian humidity. Applying two coats of primer on porous surfaces like old concrete tiles provides a more effective seal than a single thin layer.
4. Rust and Corrosion Under the Paint
On metal roofs, rust is a progressive disease that destroys the bond between the metal and the coating. Even a small amount of surface corrosion can spread under a fresh coat of paint, causing it to flake off in large sections. Standard roof paints are not designed to neutralise rust; they only hide it temporarily.
The Solution:
Inspect the roof for rust patches before painting. Rusted areas must be treated with a Rust Inhibitor Primer that converts corrosion into a stable surface. This stops the oxidation process and provides a base that the topcoat can actually stick to.
5. Environmental Stress and Low-Grade Product Choice
The Australian sun provides some of the highest UV exposure in the world, which breaks down the polymers in cheap paints. When these polymers degrade, the paint becomes brittle, chalky, and eventually cracks. Once the paint film is cracked, water enters behind the layer, leading to widespread peeling.
The Solution:
Invest in a professional-grade coating system like Roof Protect or 20-Year Roof Protect. These products are formulated with flexible polymers and UV-resistant additives specifically designed to accommodate the rapid temperature shifts seen in South East Queensland.
Restore Your Roof for the Long Term
A peeling roof is a sign that your home’s primary defence is failing.We provide Australian-made coating systems engineered to stop the cycle of delamination. Our products are formulated to ensure they withstand the specific heat and humidity of regions like Toowoomba and Ipswich.
If you are dealing with a failing roof coating, don't just paint over the problem. Use the right product and treatment.
Find more of our product here.