Rendered outdoor bench with two open recesses under construction
07
Nov

Cracked or Blown Render on a Darwin Home: Causes and Repairs

Render protects the walls of many Darwin homes, but cracks and hollow patches are common once it has been through a few wet seasons. A hairline crack is a cosmetic job. A blown patch that sounds hollow, or a crack that keeps reopening, is letting water into the wall.

What causes render to crack or blow

  • Movement: buildings expand, contract and settle, especially around window corners and openings
  • Water getting in: from roof or gutter overflow, leaking pipes or cracks that were never sealed
  • Poor preparation: render applied over dusty, unprimed or too-smooth surfaces does not bond well
  • Moisture behind the wall: trapped water pushes the render off from behind
  • Impact or age: knocks, fixings and old patches that were never blended in

How to spot a blown patch

Tap the wall lightly with your knuckle or the handle of a screwdriver. Solid render sounds dull and firm. A hollow, drummy sound means the render has separated from the wall behind it. Also look for cracks that run in a stepped line, stains below windows and bubbling paint.

How a proper render repair is done

  1. Find and fix the source of the moisture, such as a leaking gutter or pipe
  2. Cut back to sound, well-bonded render and remove everything loose
  3. Clean and prepare the surface so the new render can grip
  4. Apply the new render in layers, matching the thickness and texture of the surrounding wall
  5. Let it cure, then seal and paint so the patch blends in

Skipping the first step is the most common reason repairs fail. If water keeps getting in, the new patch will come away just like the old one.

When a patch is not enough

If cracks are wide, keep growing, or run through the full wall, have the cause assessed before patching. Large areas of failed render are sometimes better re-done as a whole wall so the finish is even.

Our plastering and render repairs service covers cracked and blown render as well as gyprock and ceiling repairs, and our painting team can finish the wall so the repair disappears. If the damp is coming from the roof, see our roof repairs service.

Need a hand? Request a free quote online or call Florance Property Solutions on (08) 8983 3000. We look after homes, rentals and businesses across Darwin, Palmerston, Howard Springs, Humpty Doo and the rural area.