Roundtower Board Render is a dry, ready-mixed Natural Hydraulic Lime (NHL) render designed as a high-performance backing coat & base coat for bonding and plastering insulation boards. With enhanced workability and consistent performance, this render is ideal for heritage and eco-build projects that require a breathable, vapour-open solution.
Blended from:
-
100% pure NHL 3.5
-
Graded kiln-dried sands
-
Carefully selected conservation-grade additives
This render provides:
-
Excellent adhesion to insulation boards prior to mechanical fixing as well as a base coat onto wood fibre boards.
-
Improved workability and extended open time.
-
Reduced shrinkage risk.
-
Reliable performance across a variety of solid wall backgrounds
✔️ Purpose: Backing render for board adhesion before mechanical fixing & base coat onto wood fibre boards.
✔️ Binder Strength: NHL 3.5
✔️ Yield: 14.5 litres of mortar per 25kg bag
✔️ Colour: Natural tan (no pigments added; not a finish coat)
✔️ Application Method: Apply with a notched trowel to the full back of the board
✔️ Part of the Roundtower Performance Range: Precision-engineered for compatibility with breathable build-ups
This lime-based board render is ideal for internal or external applications where breathable insulation boards (e.g., wood fibre) are used. It ensures effective load transfer, board alignment, and moisture-safe build-up in both traditional and modern breathable wall systems.
