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.

• Cement render The traditional sand and cement render on solid brick and cavity brick homes across Melbourne. Cracks with movement, and debonds where moisture gets behind it.
• Acrylic and polymer render Flexible modern render systems, often over blueboard or foam panel. Cracks at sheet joints and around openings, and fails where the substrate was not prepared or the system was not finished with its topcoat.
• Foam (EPS) render systems Rendered polystyrene cladding on many 1990s to 2010s homes and units. Impact damage, water entry at penetrations and windows, and drummy areas where the base coat has debonded.
• Textured and coloured finishes Trowel-on and roll-on texture coatings in a colour that has to be matched, not just painted over.
• Venetian plaster and specialist finishes Our team includes a Venetian plasterer with more than 34 years of experience, and our director is licensed by Dulux Acratex for Venetian plaster and rendering.
• Heritage lime render Soft lime renders on period homes, which need to be repaired in a compatible material or the repair damages the wall.

A single crack or a small drummy area on an otherwise sound wall is a patch repair: cut out, key, rebuild in coats, texture and colour match, feather out. The finished result is good but rarely invisible under raking light, because render is a hand-applied finish and no two areas are identical.

Once a wall has several cracks, previous patches or widespread crazing, patching becomes a false economy. Repairing the failed areas and then recoating the full elevation, or the wall to a natural break such as a corner or downpipe, gives a uniform finish and a flexible protective coating over the whole surface. We quote both options where both are realistic and tell you which one we would choose on our own house.

Rendering over a moving or wet wall is the render repair that fails. Before we put render back on, the reason it cracked has to be dealt with. If the crack is stepped or diagonal and continues into the brickwork, that is footing or wall movement and the masonry is stabilised first with HeliFix crack stitching. If the render is drummy and damp, we find the water: a failed window flashing, a blocked weep hole, a leaking downpipe, a cracked parapet capping, or a balcony above. If a steel lintel is rusting and lifting the brickwork over a window, the lintel is repaired before the render.

That is why we describe our render repairs as fixed at the cause. The rendering itself is the easy part; knowing what to do before rendering is what makes it last.

A repaired render wall should be finished with a flexible, breathable membrane coating rather than ordinary exterior paint. A good elastomeric coating bridges hairline movement, keeps water out of the render and lets moisture in the wall dry outward. Our director is licensed by Dulux Acratex, and on full-system work we install the complete Acratex system from primer to topcoat, which carries the manufacturer’s system warranty in addition to our workmanship warranty. Details are on our warranty page.

Hairline crazing on a sound wall can be filled with a flexible exterior filler and painted, and if that is all you have, we would tell you so rather than quote for it. The problem with DIY on anything larger is that the crack is a symptom. Filling and painting a movement crack means the crack comes back through the paint the following summer, and filling a drummy area means the render around the filler keeps debonding. If a crack is wider than a couple of millimetres, is growing, is stepped or diagonal, or the wall sounds hollow around it, it needs assessing, not filling.

Render repairs are priced on the area to be cut out and rebuilt, whether the cause needs a separate repair such as crack stitching or a lintel, the access (ground level, ladder, scaffold or an elevated work platform), the finish to be matched, and whether the elevation is being patched or recoated. A single crack on a single-storey wall is a small job. A two-storey rendered facade with movement cracking, a drummy area over a rusted lintel and a full recoat is a substantial one.

We inspect and provide a written quote at no charge, and the quote sets out exactly what is included and why.

• What causes render to crack? Movement in the wall behind it on Melbourne’s reactive clay soils, moisture getting behind the render from a failed flashing or leaking downpipe, hard cement render over soft old brickwork, shrinkage from render applied too thickly or in the wrong weather, and large areas with no control joints. The repair depends on which cause you have.
• Is cracked render a structural problem? Fine, evenly spread hairline crazing is usually shrinkage and cosmetic. Stepped or diagonal cracks, cracks wider than about 2mm, cracks that continue on the inside of the same wall, or cracks that have grown point to movement in the wall behind and should be assessed.
• Can you just fill and paint cracked render? Only hairline crazing on a sound wall. A movement crack that is filled and painted comes back through the paint, usually the following summer, because nothing was done about what caused it. We fix the cause first and then repair the render.
• How do you match the existing render? By matching the aggregate, texture, sheen and colour, and feathering the repair out rather than stopping at a hard edge. Where a wall has too many repairs to blend we recommend recoating the whole elevation to a natural break, which gives a uniform finish.
• Do you repair acrylic and foam render as well as cement render? Yes. We repair cement render, acrylic and polymer render systems, rendered foam (EPS) cladding, textured coatings, heritage lime render and Venetian plaster finishes.
• How long does a render repair take? A single crack or patch is usually a day or two on site plus curing between coats. Fixing the cause first, such as crack stitching, adds time, and a full elevation recoat on a two-storey house is typically around a week depending on weather.
• Do render repairs come with a warranty? Yes. All our work carries a written workmanship warranty, and where we install a full Dulux Acratex coating system the manufacturer’s system warranty applies as well. Our warranty page sets out the details.

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