Achieve a Stunning Granite Finish Effortlessly

The existing sill needs to be clean, stable and ready to accept the Decosill render. This is what makes Decosill so practical: you’re working with what’s already there.

• Remove all loose, flaking or powdering material with a stiff brush or scraper
• Clean away dirt, moss, algae and any paint that is lifting
• Fill deep cracks or voids with a suitable repair mortar and allow to cure
• Lightly dampen the surface and apply a bonding primer (SBR or equivalent) to maximise adhesion
• Mask the window frame and surrounding wall with tape and sheeting

Before Decosill is applied, a Quartz primer coat must be applied to the prepared surface. This critical step ensures maximum adhesion between the existing substrate and the render, and creates the key the stone chip needs to bond permanently.

• Apply the Quartz primer evenly across the full sill surface using a brush or roller
• Ensure complete coverage with no dry patches or missed edges
• Allow the primer to become touch-dry before applying Decosill — do not apply onto a wet primer coat
• Do not skip this step — the primer is what gives Decosill its long-term bond and durability

Decosill comes ready to mix — the natural stone chip aggregate is already blended into the product. Using a drill or paddle mixer, further mix to a smooth working consistency, and apply directly to the prepared sill.

• Apply to the sill with a steel trowel, working to an even depth of approximately 1-2mm
• Build up the profile of the sill edge, ensuring consistent cover over the full surface
• While still fresh, use a damp sponge to soften any edges
• Level and close in the material to achieve a consistent natural looking smooth finish