With the home improvement season gaining momentum and permitted development rules relaxed, roofing contractors are looking for the best solutions to meet a growing demand for house extensions.

ISOLINE ONDUTILE roofing sheets, the BBA certified secondary roofing system from Onduline Building Products, provides a secure but lightweight waterproof barrier that’s designed to be fitted below traditional tiled roofs.

Ideal for beneath concrete, slate or clay tiles, it is perfect for very low pitch roofs, providing long-term protection against any potential water ingress that may happen over time through a breach in the primary roof covering.

Properly installed, the pitch can be as low as 12.5° for interlocking concrete tiles, 17.5° for clay pantiles, natural and fibre cement slates, and 22.5° for plain double lap tiles.

Bituminous corrugated sheeting

30 year waterproofing guarantee

Heritage buildings and extensions

ISOLINE ONDUTILE Underlays for heritage buildings

Lightweight and sustainable

Bituminous corrugated underlay sheeting

Multiple benefits

  • Thermal insulation – the provision of an ISOLINE ONDUTILE secondary roofing system significantly improves the thermal performance of the roof structure.
  • Sound insulation – provides a 27% reduction in sound penetration through the roof covering.
  • Ventilation – sheet corrugations supply 17000mm2 per linear metre ventilation above the sheet into the tile batten cavity and below into the roof space.
  • Moisture control – tile battens positioned above the corrugations allow moisture to drain to the eaves which, with enhanced ventilation, maintains excellent moisture control within the cavity.
  • Safety – forms a tough, non-reflective and safe working environment during roofing works.