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How to repair flaking render?

Sn0wy
Getting Established

How to repair flaking render?

Hi all,

When we built our home the builder rendered over the edge of the exposed concrete footing it seems (just below the tiled alfresco area and also out the front porch) and painted it in Colorbond Monument. Over time, the render has started to flake and powder — I can even rub it with my finger and it comes off like sand. It really spoils the look of the house.

I have the Colorbond paint to tidy it up, but I’m not sure of the best long-term fix:

  • Should I just paint over the existing render?

  • Or would it be better to remove the failing render completely and paint directly onto the concrete footing?

  • Is rendering over footings a standard practice, or should it have been done differently in the first place?

I’ve attached a couple of photos for reference. I’d love some advice on the right approach and what tools/materials I should use to fix it properly so it doesn’t keep flaking.

Thanks in advance!

20250909_112713.jpg20250909_112722.jpg

MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: flaking render/removal and repair?

Hi @Sn0wy,

 

It sounds like the render is quite compromised if it’s coming off like sand, so simply painting over it probably won’t give a lasting result. The paint will just flake off as the render continues to disintegrate. It’s worth doing a bit of exploratory work first, like using a wire brush to see how much of the render is loose and coming away easily. Painting directly onto the concrete slab isn’t ideal either, as it will likely sit recessed and won’t give a smooth, finished look.

 

The most reliable approach would be to remove the failing render completely, chisel it off, then re-render the area before painting once it’s fully dry. Alternatively, you could consider installing an aluminium edging across the area. This can give a clean, durable finish without needing to rely on render, and could look quite neat on the edge of the footing. Another option might be tiling the edge, if you can find the same tiles.

 

Please let me know if you have any questions.

 

Mitchell

 

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Sn0wy
Getting Established

Re: flaking render/removal and repair?

Thanks Mitch!

 

mind me asking whats the difference between these below? or which I would use? - assuming to be painted later

https://www.bunnings.com.au/dingo-fast-set-mortar-3kg_p0760518?store=8201&gclid=EAIaIQobChMItoaEwKCl... 

https://www.bunnings.com.au/davco-20kg-pm-render_p0034888 

MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: flaking render/removal and repair?

The main difference between the two products is their intended purpose and finish, @Sn0wy. The Dingo Fast Set Mortar is designed for quick-setting repairs, such as patching small holes or gaps in brick, block, or stone surfaces. While it sets rapidly, it’s more suited for minor fixes and won’t provide the smooth, consistent finish needed for a larger rendered area. The Davco PM Render, on the other hand, is specifically formulated for rendering applications on substrates like brickwork, concrete, and fibre cement. It’s pre-blended, easy to work with, and provides excellent adhesion, making it ideal for preparing surfaces to be painted. For your project, where the goal is to repair and paint, the Davco PM Render would be the better choice.

 

Mitchell

 

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Sn0wy
Getting Established

Re: flaking render/removal and repair?

Thanks Mitch, do any of the other renders in Bunnings require adding a bonding agent, e.g Bondcrete or something like that? or do I just following the directions on the packaging?

JacobZ
Bunnings Team Member
Bunnings Team Member

Re: flaking render/removal and repair?

Hi @Sn0wy,

 

Sometimes they recommend a primer or bonding agent; other times, they don't. It can differ from product to product, so it is usually best to check the instructions on the packaging. 

 

You can also Google the specific product's name, followed by TDS (technical data sheet), to find a document with information on its application.

 

For example, the Davco 20kg PM Render does not mention using a bonding agent, so I wouldn't use one.

 

Let me know if you have any further questions.

 

Jacob

 

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