Warm Roof Insulated Drains

The situation

NZBC Clause H1 Energy Efficiency now requires substantially higher minimum R-values across the building, with the roof identified as the area of most cost-efficient gain. As warm roof construction gains popularity across New Zealand’s commercial & residential sectors, the drain penetration has become a recurring point of failure between design intent and delivery.

The problem

The drain penetration itself has long been treated as a detail outside the insulation layer. In a box gutter, for example, the void around the drain body has been an after-thought, often packed with off-cuts of insulation and expanding foam in an ad-hoc manner on site. This approach compromises the continuity of the thermal envelope and introduces a localised cold bridge at precisely the point most exposed to water and thermal movement — with the finished result depending heavily on the skill and diligence of whoever is on the roof that day.

Our Design-Led Solution

Aquaknight’s insulated warm roof drain addresses this by supplying the drain body as a factory over-moulded block of closed-cell foam, matched to and exceeding the thermal performance of the surrounding insulation board. For residential application, the unit is manufactured to a standard 300×300mm format matching New Zealand’s minimum box-gutter width, and supplied to any panel thickness so it integrates directly into the warm-roof specification set by the membrane manufacturer. Units are secured by direct fixing into the substrate, delivering a consistent, pre-insulated component.