Dræningsrender

Dræningsrender, or drainage render, is an exterior wall coating designed to manage moisture in masonry by creating a drainage and ventilation path behind the render. It is commonly used on brick, block, or concrete walls and is chosen for buildings where damp, capillary rise, or high exterior moisture can threaten the wall system. The key feature is a drainage layer or backing that forms a small air and water collection chamber between the masonry substrate and the outer render, allowing water that penetrates the surface to drain away and the wall to dry more effectively.

System components and construction methods vary. Some drainage renders use a cementitious or mineral render with an integrated or attached drainage layer, such as perforated backing, ribbed profiles, or a spacer mesh that maintains an air gap. The render is typically applied over a suitable base coat and reinforced with mesh, followed by a protective topcoat. The design aims to channel any infiltrating moisture downward to drainage outlets, weep holes, or a ventilated bottom edge, while the ventilated gap promotes evaporation and reduces surface damp near the finish.

Applications and considerations. Dræningsrender is used on exterior walls where moisture management is a priority, including renovations and new builds in damp climates or on walls susceptible to wind-driven rain. It is not a cure for existing rising damp inside walls; proper substrate preparation, weatherproofing, and detailing at connections, joints, and penetrations are essential. Compatibility with insulation systems and finishes, maintenance requirements, and cost considerations are important when choosing this solution.