Cracked Render: Repair or Replace?

A fine hairline crack in an otherwise sound wall is often a surface issue that can be patched. Render that sounds hollow or drummy when tapped, however, has usually let go from the wall behind it, and patching over a section that is no longer properly bonded rarely holds for long.

If a crack lines up with a stain, a damp patch, or a musty smell inside, water is very likely getting behind the render rather than just sitting on the surface. That changes the job from a cosmetic repair to one that needs the water ingress addressed first, or the same crack tends to come back.

A single crack or a small section is usually a straightforward repair. Render that has failed in multiple places across the same wall, or that has come away in several spots, is often a sign the whole surface has reached the end of its life, and a full re-render is the more practical option rather than chasing individual patches indefinitely.

Whatever the scope, the goal of a repair is for it to disappear into the wall once finished. That means cutting out the damaged section properly, repairing it and blending the texture back to match the surrounding render, rather than leaving a visibly different patch that stands out more than the original crack did.