Guide to Concrete Repairs


As body corporate painting experts, it is our job to know the ins and outs of the issues that can plague concrete and render. We always perform a thorough building inspection prior to quoting to identify these issues and determine what repairs are necessary as part of the painting process.


Example of cracks in concrete Concrete cracking is easy to spot, but the underlying cause needs to be found

Cracking of render and concrete is common and is caused by a wide range of underlying issues.

If the render is new and already cracking, it’s possible that the render mixture contained had too much water or it dried too fast, causing the exterior surface to harden while there was moisture trapped in the interior. If the cracking developed over time then it’s possibly due to foundation subsidence, where the ground beneath the structure shifts. This may be a result of vegetation, water damage, or poorly compacted soil.

­The Fix

The cause of the cracking first needs to be identified to determine if further structural repairs are necessary. Following this, we work to repair the cracks themselves. After grinding the cracking to specified widths and depths, we prime and fill with a premium polyurethane sealant, cutting it flush with the surface. Finally, we apply a coating and texture to match the surrounding wall.



An example of efflorescence caused by alkaline salt leaching An example of efflorescence caused by alkaline salt leaching

Alkaline salts are present in most forms of masonry, including concrete and render. When moisture migrates through the masonry, the salts leach out of the material, causing a build-up of a white crystal substance on the surface. This process is known as alkaline salt leaching and causes efflorescence a.k.a the build-up of crystallised salts on the material’s surface. If the masonry is coated by paint, the paint may start to crack, peel, or flake as a result of the build-up of salts beneath.

The Fix

Once confident that the source of the moisture has been controlled, the existing paintwork needs to be stripped and the salts need to be removed. This is done using an acidic solution to neutralise the alkaline salts. When it is time to recoat, we would recommend using a product designed to resist future water ingress. Our teams prefer to use a two-pack hydrostatic hold out epoxy membrane.

Blistering and Peeling Paint

An example of blistering paint Blistering occurs most commonly from moisture build up beneath the paint layer

Blistering of paint occurs when moisture emigrates through the building material and lifts the paint coating from the overlying surface. For this reason, when we see blistering paint we inspect for other signs of water damage and look for the source of water ingress.

The Fix

Repairing areas of blistering and peeling paint is as simple as removing the existing paintwork and then recoating. To avoid recurrence of the issue, however, it is important that the source of water ingress is rectified. It is similarly advisable to use a waterproof coating, such as a two-pack hydrostatic hold out epoxy membrane.


Concrete Spalling

An example of concrete spalling Advanced concrete spalling with exposure of the steelwork.

Concrete spalling is a serious structural issue that is caused by rusting of the steel reinforcement within a concrete slab. When the steel rusts, it increases in size, displacing the concrete and causing sheets of concrete to flake and fall from the building. Once there is a break in the integrity of the concrete slab, water can enter and react with the steel, causing further rust and spalling. In this way, the problem can quickly spread, becoming dangerous and costly to fix.

Whilst the appearance of advanced concrete spalling is unmistakeable, it will often start as discoloration or staining of the concrete, masking the underlying problem. Inspection by a body corporate painting professional is vital in ensuring early detection of this issue.

The Fix

Because of the self-propagating nature of concrete spalling, repair work for this issue must be meticulous, and it is important to identify all affected areas and their extent. When working on an area affected by concrete spalling, we remove all unstable concrete from the building. We then take the affected steel reinforcement and weld new reinforcement in place. Any existing steel that was not affected is ground clean and then coated for protection before the area is filled with a high MPA strength concrete repair mortar.


The Importance of Property Inspection

Concrete and render problems can be difficult to identify and costly to repair if left unmanaged. If you are looking to paint a body corporate or commercial property, protect yourself by making sure that a detailed property inspection is performed.

At Darryl Hathway Painting and Decorating, our dedicated body corporate manager has an intricate knowledge of these issues and inspects all body corporate sites prior to quoting. By doing this we can provide our clients with the most accurate possible quotation, reducing the risk of unforeseen costs. To talk to us or book your inspection today, call us on (07) 3395 7930.



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Darryl Hathway

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