Universal Underlay

SBS Modified Torch-on Underlay

Universal Underlay is a torch-applied underlay membrane which is designed to be used as part of a torch-applied built-up roofing system. It features a glass fibre core which is saturated and coated in SBS modified bitumen and the upper surface is finished in light sand.

When incorporated in a suitably designed and installed multi-layer system, maintained in accordance with BS 8217:2005 – Reinforced bitumen membranes for roofing, Universal Underlay may be expected to last in excess of 15 years.

Key Features & Benefits:

• Waterproofing underlay

• Glass fibre core

• SBS modified bitumen

• Extra flexibility


Universal Underlay

Accreditations and Certifications

Product Information
Product CodeRoll LengthRoll WidthPallet Quantity
P83816m1m30 rolls


To complete a full system, Universal Underlay is fitted above the venting base sheet, or a suitable preparation layer, prior to the final waterproofing layer. When used as part of a multi-layer built up roofing system, it provides long-lasting waterproofing performance and is readily suited to various types of flat roofing projects, including new build and refurbishments, cold roofs and warm roofs using vapour control layers with insulation.

Installation Guidelines

This product should be installed in accordance with manufacturer recommendations and all relevant national standards and codes of practice, including BS 8217:2005 – the code of practice for reinforced bitumen membranes for roofing.

Maintenance and Repair

Routine inspection, cleaning and maintenance of the roof membranes should be based on the recommendation in BS 8217:2005. Should it be damaged either during construction or at a later date, then the repairs should be made using the same materials so that the performance of the built-up membranes is retained.


Manufactured in accordance with BS EN 13707:2004+A2:2009 – Flexible sheets for waterproofing. Reinforced bitumen sheets for roof waterproofing.

Handling and Storage

The material should be stored vertically on a firm flat surface, and transported stood on end to avoid damage.

Health and Safety

Health and Safety should be observed at all times in accordance with HSE and industry guidance. Specific Risk Assessments and Method Statements should be produced by contractors where necessary to ensure Working at Heights, Fire Safety and Manual Handling rules are compliant with current law and regulations. Health and safety data sheets are available for all materials on request from Chesterfelt.


UKCA certified & CE Marked to EN 13707:2004+A2:2009.
CE Certificate Number: 0086-CPR-595938.
UKCA Certificate Number: 0086 CPR 753192.

Quality Assurance

Universal Underlay is manufactured in accordance with BS EN ISO 9001:2015 – Quality Management Systems (QMS).

Associated Products

Chesterfelt high performance torch-on cap sheets.

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