How to patch and level a rendered surface?

Leeroy Jenkins

I’ve scraped off the loose paint and tried patching it with Polyfilla External Masonary. Need some suggestion if there are better products I can get to better fill the gaps to level it?

Also what tool(s) is beat to sand down the excess render/polyfilla?

Once the surface is prepped, I am thinking of painting it with some textured paint to retain consistency with the wall render.

Need some suggestion/ideas to get started. Thanks

MitchellMc

Welcome to the Bunnings Workshop community @Leeroy Jenkins . It's wonderful to have you join us and many thanks for your question on repairing render.

Polyfilla External Masonry is okay for small nail holes and minor defects, but for what you’re showing there (larger low spots and uneven render), you’ll likely get a much better result using a render-specific patching product, such as Dunlop 4L Premix Render Joint And Patch. It’s designed to bond to existing cement render, build up thicker sections without slumping, and feather out properly. It’ll also be more durable long term than standard masonry filler.

After scraping off all loose paint and material (which you’ve already done), make sure the surface is clean and dust-free. If the surface is very dry and porous, lightly dampen it before applying a cement-based patch. This helps with adhesion. Apply the render patch with a steel trowel. Press it firmly into the voids first, then build it out slightly proud of the surface. It’s better to apply in two thinner coats rather than one thick coat if you’re filling deeper areas.

To blend it level with the surrounding render: Use a straight edge or wide trowel to skim across the surface. Try to match the existing texture while the product is still workable.

For small areas, sand the area use 80–120 grit sandpaper on a sanding block. For larger areas, a random orbital sander with 80–120 grit discs works well. Be careful not to oversand the surrounding original render. Remember you PPE included a P2 respirator and safety glasses.

Using a textured exterior paint is a good idea to help blend everything visually. It won’t hide major unevenness, so get the surface as flat and consistent as you can first. Once patched and sanded, prime the repaired areas (especially if you’ve exposed bare render). Then apply the textured paint over the entire section for uniformity.

Here's a helpful guide: How to repair a rendered wall.

Please let me know if you have any questions.

Mitchell