How to fix cracks and a chipped corner on exterior render?

Question

Hi team,

I’m a DIY beginner, so I’m looking for the simplest way to repair these areas:

• Cracks in the rendered wall

• A gap between the wall and window frame

• A chipped corner on the exterior rendered wall

This property previously had a structural issue and has already had resin injection treatment.

What products and repair methods would you recommend for each area? I’d especially appreciate advice on what type of filler/patching product and sealant I should use.

Thanks in advance!

MitchellMc · Answer

It sounds like you've taken a sensible approach by monitoring the cracks, @Tonto3. If there's been no noticeable movement since December, I'd be comfortable proceeding with the repairs rather than waiting longer.

I'd still recommend keeping your photos for comparison and monitoring the repaired areas over time. If the cracks reopen or new cracking develops, that would be a good reason to have the underlying issue reassessed.

You can also go ahead and seal the gap between the window frame and render with the flexible exterior-grade sealant. That's exactly where you'd want a flexible product, as it can accommodate a small amount of movement between the two surfaces.

Mitchell

Tonto3 · Answer

Thanks for the detailed advice @MitchellMc — that’s really helpful.

The resin injection was done in October, and I also took photos of the cracks in December so I could monitor whether they were changing. I’ve compared the photos with the current condition, and so far I can’t see any significant change in the cracks.

Would you recommend waiting a little longer before repairing the cracks, just to make sure they remain stable? Or does the fact that they haven’t noticeably changed since December give enough indication that I can go ahead with the repairs?

In the meantime, would it be okay to seal the gap between the window frame and the render with the flexible exterior-grade sealant you mentioned?

Thanks again!

MitchellMc · Answer

Welcome to the Bunnings Workshop community @Tonto3. It’s great to have you with us and many thanks for your question.

I'd recommend starting by taking a look through our guide on How to repair a rendered wall, which will give you a good overview of the repair process.

For the cracks, remove any loose or crumbling render, open the cracks slightly with a scraper if necessary to provide a sound surface, clean away the dust and patch them with a suitable exterior render repair compound. The larger cracks in your photos might take a couple of applications.

For the chipped corner, remove anything loose and rebuild the missing section with render repair mortar. You can use a straight edge or trowel to recreate the corner and then blend the surface texture into the surrounding render before painting.

The gap where the render meets the window frame is a little different. As the frame and wall can move independently, I'd use a flexible, exterior-grade paintable sealant rather than a rigid filler.

Since you've mentioned that the property previously had a structural issue, I'd also suggest checking whether these cracks are old and stable before repairing them. If they're continuing to widen or reappear following the resin injection work, it would be worth having the area reassessed before covering them over.

Let me tag @rchreno, @WombatRenno, @alex617 and @handyfrog, who have all dealt with cracked render in the past, to see if they have any thoughts.

Please let me know if you have any questions.

Mitchell