K-Rend render clean — Newton Mearns detached

The problem

• • Heavy green algae on north-facing rear elevation.
• • Pink staining (Trentepohlia) on the west gable from prevailing rain.
• • Owner had been quoted to pressure-wash the render — which would have voided the K-Rend warranty.
• • Previous DIY attempt with a domestic sprayer had streaked the south elevation worse.

Our approach

1. 1. Pre-soaked all elevations with a K-Rend-compliant render-safe biocide blend.
2. 2. 20-minute dwell time per elevation — let the chemistry do the work, not the pressure.
3. 3. Low-pressure rinse with a wide-fan nozzle under 200 psi — manufacturer-compliant.
4. 4. Spot-treated the pink staining with a second biocide pass.
5. 5. Final biocide top-up across all elevations once dry.

The outcome

• All four elevations back to clean white finish.
• K-Rend warranty preserved — full record of method kept on file for the owner.
• 3-year maintenance plan agreed: annual biocide top-up at £180/year vs full re-clean every 18 months without it.