Silicone or Acrylic Render? Choosing a Finish for Irish Weather

On a wet, sheltered gable in Ireland, the difference between a render that still looks well after ten years and one that goes green in three comes down to what you spread on it.

Acrylic render

Acrylic is tough, sticks well and comes in every colour. Its weakness is breathability: it forms a relatively closed film, so moisture that gets into the system has a harder time leaving. On a sheltered north-facing wall that never dries out, that is exactly the condition algae like.

Silicone render

Silicone renders are vapour-open and strongly water-repellent at the same time. Rain beads and runs off, carrying dirt with it, while water vapour from inside the wall can still escape. In a climate where walls are damp for weeks at a time, that combination is worth paying for.

We stock two:

• Ceresit CT74, 1.5 mm grain, 25kg bucket
• Ceresit CT76, 1.5 mm grain, 25kg bucket, with the self-cleaning formulation

Both cover about 9 m2 per bucket at 1.5 mm, and both pages have a calculator so you can turn your wall area into a number of buckets.

Grain size, in plain terms

The grain number is the size of the aggregate, and it sets both the texture and how much you use. A 1.5 mm render gives a fine, even scratch texture and is the usual choice on houses. Coarser grains cover imperfections better but eat more material per square metre and read as heavier at close range.

Getting it to last

• Prime first. Render applied straight onto a base coat without primer will not bond evenly and will show patchy suction.
• Do not render in the wrong weather. Below about 5°C or in direct hot sun, both are bad. Overnight frost on green render is fatal.
• Work wall by wall, wet on wet. Stopping mid-elevation for lunch leaves a visible joint that never disappears.
• Mind the detailing. Most render failures start at a badly formed reveal or a missing drip bead, not in the middle of a wall.

Need a hand with your job?

Send us your measurements and we will put together a materials list with prices. Call 085 868 8459, message us on WhatsApp or email sales@all4building.ie. We deliver across Ireland from our Cork warehouse.