Design & Installation Guide

A number of design considerations need to be taken into account when constructing new pitched roofs or in refurbishment of existing roofs. The area of application will determine the minimum product choice from the Icopal range in terms of ventilation required or mechanical performance.

For a quick over-view pitched roof underlay, please consult the Icopal Pitched Roofing Product Selector or for more detailed design information, click on the links below. 


Warm Pitched Roof - Roof Space: Unventilated and Sealed

Eliminating traditional ventilation and the potential condensation risk associated with large voids of cool air make this the optimum pitched roof solution. With the potential of additional living space, a cathedral roof design or a conditioned roof void are rapidly becoming the preferred choice of pitched roof construction in the UK.

Warm Pitched Roof - Roof Space: Ventilated and Sealed

A sealed warm roof construction can also be achieved by creating a 50mm ventilated air gap between the surface of the insulation and the undertile lining to allow water vapour to be safely removed from the roof construction.

Cold Pitched Roof - Roof Space: Ventilated

This traditional roof construction uses movement of air through the roof void to prevent the occurrence of harmful condensation.


Cold Pitched Roof - Roof Space: Unventilated and Sealed

The sealed cold roof system does not need the provision of ventilation directly into the loft space and works on the principle of a Monarperm vapour open or permeable underlay being used under the roof tiles simply allowing vapour drive to diffuse any water vapour harmlessly into the batten space and the external atmosphere beyond.
Read more... 


Boarded or Sarked Pitched Roofs

Typically a Scottish practice, the roofing underlay is laid directly over a series of sarking boards fixed to the roof rafters. 

Roofing Underlays - Recommended Headlaps and Sidelaps

Headlaps and sidelaps to roofing underlays should comply with the recommendations of BS5534: 2014: Code of Practice for Slating and Tiling and BS 8000-6: 1990 Workmanship on Building Sites.

General Site Work and Health & Safety

Read more about the procedures that should be adopted when installing Icopal undertile linings.


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