Textured Coating Calculator — Coverage by Texture Depth

For weight-sold Pliolite-type wall coatings (25 kg tubs), coverage depends on texture: a fine/spray finish uses about 1.25 kg/m² (Wethertex MP44 spray covers 10–20 m²/25 kg), a medium roller texture about 1.7 kg/m² (Wethertex LD77 ~15 m²/25 kg), and a heavy trowel/bark finish about 2.5 kg/m² (Wethertex HD77 ~10 m²/25 kg). A real 25 kg tub therefore covers roughly 10–20 m². A true Tyrolean is a trowel/machine-applied render, not a thin coating, and uses far more — around 13.5 kg/m² (about 1.85 m² per 25 kg bag at 7 mm, Cornerstone Performance Tyrolean). Always add 10% for wastage; absorbent substrates use more.

Yes, a stabilising primer is essential on friable (crumbly), chalky, or powdery surfaces. It binds loose material and provides a key for the textured coating. Sandtex Quick Dry Stabilising Solution covers 6–10 m²/L on sound surfaces, dropping toward the lower end on very absorbent or powdery walls — which is exactly where it is needed — so this calculator estimates a conservative 6 m²/L. Allow around 4 hours to dry. On sound, well-adhered surfaces you may be able to skip the stabiliser, but it is cheap insurance against failure.

Yes, provided the existing paint is sound and well-adhered. Scrape off any loose or flaking paint, fill cracks with flexible filler, and apply a stabiliser coat. Textured coatings are thick enough to bridge fine cracks (up to 1mm). For larger cracks, use a flexible masonry crack filler first. Do not apply over gloss paint — it must be removed or roughened.

Quality textured masonry coatings last 15-25 years on exterior walls. They're more durable than standard masonry paint because the thicker coating provides better weather protection. The texture also helps shed rainwater. Recoating is simpler than the first application as the existing texture provides a good base. Products like Dulux Weathershield Textured carry 15-year guarantees.

For stipple and swirl effects, use a heavy-duty roller then texture with a stipple brush or comb while wet. For bark effects, use a notched trowel or bark roller. For Tyrolean finishes, a Tyrolean flicker machine throws the coating onto the wall. A plasterer's hawk and trowel work best for roughcast. Always work in manageable sections to avoid drying edges.