That makes it the correct choice for a large share of modern Sydney work. Anything on blueboard or Hebel, anything within reach of salt air, anything on a reactive clay site, and anything where the client wants a colour through finish they never have to repaint.
Why acrylic instead of straight cement
The polymer content does three useful things at once. It makes the render flexible enough to absorb the daily expansion and contraction a wall goes through. It dramatically improves adhesion, which means it will bond to substrates plain cement render slides straight off. And it makes the finished surface far less permeable to wind driven rain while still letting vapour out.
The trade off is cost. Acrylic systems run roughly thirty to fifty percent above a plain cement render. On the right wall that is money well spent. On a stable double brick wall in an inland suburb it may well be money you do not need to spend, and we will say so.
Where acrylic render earns its cost
There are four situations where we will push you towards acrylic almost every time.
- Coastal exposure. Salt attack is the number one cause of render failure from Bondi to Cronulla and acrylic sheds it far better
- Blueboard, Hebel and other lightweight panels, which need a flexible system by design
- Reactive clay sites through western and south west Sydney where the ground moves seasonally
- Dark colours and west facing walls, where surface temperatures swing hardest
Colour through finishes
Acrylic systems can be tinted right through the material rather than painted afterwards. That means the colour is the render, not a film sitting on top of it.
The practical benefit is that a chip or a scratch shows the same colour underneath instead of a white scar, and there is no paint film to blister, peel or fade off unevenly. You are not committing to a repaint every seven to ten years.
The catch is that you have to be certain about the colour, because changing it later means painting over the top, which puts you back where you started. We bring samples and we will leave them on the wall so you can see them in morning light and afternoon light before you commit.
How the system goes together
On a masonry wall we generally apply a cement render base coat to get the wall flat and true, let it cure, then apply the acrylic top coat and texture. On blueboard or Hebel the acrylic base coat goes directly onto the panel with reinforcing mesh embedded at every sheet joint.
That mesh is not optional and it is the most commonly skipped step in the trade. Sheet joints are exactly where a panel wall moves. Without mesh across them you will have a crack tracing every joint within two summers.
