POLYFOAM XPS SETS OUT GUIDANCE ON CAVITY WALL INSULATION SOLUTIONS BELOW DPC

A new white paper from Polyfoam XPS aims to provide specifiers and contractors with advice on insulating cavity walls below damp proof course (DPC) level, while guarding against moisture risk.

“Our technical helpdesk regularly gets asked about improving the thermal performance of junctions between ground floors and external walls,” said Rob Firman, Technical and Specification Manager at Polyfoam XPS. “People want a robust and moisture tolerant insulation solution that can be installed below DPC level, and they look to extruded polystyrene (XPS) to provide that solution.”

The recent update to BS 5250, which widened its scope to address moisture in buildings generally, highlighted the increased awareness that better thermal performance must not come at the expense of other risks to the building fabric.

“Specifiers and contractors want to do the right thing and reduce thermal bridging heat losses without risking moisture uptake through the chosen insulation,” Rob Firman continued. “However, we find guidance and support is limited from building warrant providers.”

To address this lack of information, the new white paper provides a comprehensive overview of the areas of building regulations that below DPC insulation must help to satisfy. It looks at the requirement for cavity wall insulation to have BBA certification above DPC, and whether this applies below DPC as well.

Rob added: “The white paper is fully illustrated with junction details for different floor constructions. We’ve also thermally modelled the details provided, to demonstrate the low psi values that the details provide, and to show that they pose no risk of condensation internally.”

Download a copy of the below DPC insulation white paper here. For support in specifying extruded polystyrene insulation in your ground floor, flat roof, or below DPC in a cavity wall, contact us.