Render painting and crack repair in Melbourne

What we check on rendered walls

Render is cement, sand and lime. It is alkaline when new, porous, and it holds moisture, so it behaves very differently from timber. Most paint failures on render come from painting before it has cured, moisture moving through the wall from leaking gutters or garden beds, white salts on the surface, chalky old coatings, or a rigid paint film over cracks that keep opening and closing.

Our guide to painting rendered walls explains each cause and how to fix it.

Render crack repair before painting

Painting over a crack hides it for a season at most. We look at every crack before deciding what to do with it:

• Hairline cracks are filled and then bridged by the coating. On walls where they keep coming back, a flexible membrane suits better than standard paint.
• Wider cracks are raked out, filled with a flexible masonry filler and sanded flush so the repair does not show through.
• Cracks that are growing, stepping through brickwork or wider at one end can be a sign of structural movement. We point these out and recommend you get them assessed before they are painted over.

We also tap the render to find drummy patches, where it has come away from the wall behind and sounds hollow. These need repairing before any coating goes on.

Moisture, salts and new render

Crusty white salts, known as efflorescence, mean water is moving through the wall. The moisture source has to be found and fixed first, or the salts push the new paint off. Then the salts are brushed off, the wall is cleaned and sealed with an alkali-resistant sealer.

New render needs time to cure before it is coated: at least 28 days (Taubmans), and four to eight weeks before a texture coating (Dulux), depending on thickness and weather. We check moisture with a meter rather than going by how the wall looks. If you are building or extending, our new construction team plans curing time into the programme.

Paint, texture or membrane

The right coating depends on the condition of the render, which is why we recommend one after the inspection rather than before.

• Exterior acrylic masonry paint suits sound render with few cracks.
• A texture coating covers patchy or repaired render and small imperfections.
• An elastomeric membrane, such as Dulux Acratex, is flexible and high-build, so it bridges recurring hairline cracks while keeping water out.

We use premium systems from Dulux, Taubmans and Wattyl and follow the manufacturer’s preparation and coat specification for each. Dark colours absorb more heat and make render move more, so a colour consultation is worth having if you are thinking of a dark facade.

What a render job looks like day to day

Render work usually starts with a day or more of cleaning, treatment and repairs before any coating goes on, and fillers need time to dry. We cover paving, garden beds and windows before each wall, work around the forecast, and avoid painting render in direct hot sun or after a run of wet weather while the wall is still holding moisture. You do not need to be home, as long as we can reach the walls and a power and water point.

What affects the price of render painting

Render jobs are quoted after a free site inspection. The main factors are:

• The number and type of cracks, and how much repair the render needs.
• Salts, moisture or drummy patches that have to be treated first.
• The coating chosen: texture coatings and membranes use more product than standard paint.
• The height of the walls and the access around the house.

Our guide to exterior house painting costs in Melbourne gives current price ranges.