Render crack repairs Melbourne

• Structural movement Footings moving on Melbourne’s reactive clay soils, which swell in winter and shrink through summer. This shows as stepped or diagonal cracking that often continues into the masonry behind the render.
• Substrate movement The render is sound but the wall behind it has moved, so the render has to crack somewhere.
• Moisture behind the render A failed flashing, a blocked weep hole, rising damp or a leaking downpipe saturating the wall, which then pushes the render off.
• Incompatible materials Hard cement render applied over soft old brickwork. The render is stronger than what it is stuck to, so the bond fails.
• Shrinkage and workmanship Render applied too thickly, in one coat, or in the wrong weather.
• Missing control joints Large unbroken render areas with nowhere for thermal movement to go.

Fine hairline crazing spread evenly across a wall is usually shrinkage and is cosmetic. What matters more is cracking that is stepped or diagonal, cracking wider than about 2mm, cracking that has clearly grown, cracking that continues on the inside of the same wall, and render that sounds hollow when tapped. Those point to movement or debonding, and filling them is a waste of money.

1. Diagnosis — we sound the wall to map drummy and debonded areas, assess the crack pattern, and check for the moisture source or movement causing it.
2. Fix the cause — that may mean stabilising the masonry with HeliFix crack stitching, correcting drainage or flashings, or clearing weep holes before any render goes back on.
3. Remove failed render — cutting back to sound, well-bonded material rather than skimming over hollow sections.
4. Reinstate — rebuilding in coats with the appropriate mix for the substrate, using reinforcing mesh across vulnerable areas and installing control joints where they should have been.
5. Texture and colour matching — matching the existing finish so the repair is not a visible patch. This is the step most repairs fall down on.
6. Protective coating — a flexible weather-resistant membrane coating that can accommodate minor movement instead of cracking with it.

Old render is rarely flat or uniform. Matching it means matching the aggregate, the texture and the sheen as well as the colour, and feathering the repair out rather than stopping at a hard edge. Where a wall has too many repairs to blend, recoating the full elevation to a natural break line gives a far better result than a patchwork.

Render cracking frequently sits alongside masonry movement or water ingress. We also carry out HeliFix crack stitching, concrete crack repairs, brick repointing and leaking balcony repairs.

• HeliFix crack stitching
• Leaking balcony repairs
• Concrete crack repairs
• Cladding repairs