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Langley FM-20 Built-Up-Roofing System (Mechanically Fixed Installation)

The FM-20 system is a premium quality, mechanically fixed, single layer, high performance SBS elastomeric membrane warm roof system for flat or sloping roofs. Parafor Solo GFM cap sheet has a dark grey granule surface and carries an independently insured guarantee for 20 years for materials and workmanship. Note: Paradiene FM underlay is required at perimeters and openings.

When to Specify

For new-build or refurbishment projects.  Suitable for profiled metal decks (can also be considered for timber boarding or plywood, subject to fixing pull-out tests).


(1) Parafor Solo GFM, 5mm thick, 6.03kg/m².

(2) Parafoam Ultra PIR Insulation Board* 50-140mm (10mm increments), 140mm = 4.48kg/m².

(3) Visqueen LDPE Vapour Control Layer**, 250µm  thick, 0.23kg/m².

Total System Weight based on 140mm Insulation board = 10.74 kg/m²

* Insulation is available as a tapered (cut to falls) option.
** Suitable for low humidity levels only (warehouses, industrial units & storage areas).  For other applications contact Langley Technical Department.


Extremely robust, yet flexible roof covering, 5mm thick, Non-slip granule surface provides ample durability and puncture resistance for maintenance foot traffic.  Heavy duty, 180 g/m², polyester/glass composite reinforcement provides robust, watertight layer.

Assessment & Testing

GFM-20 membranes are covered by MOAT 31 (Reinforced Homogenous Coverings of SBS Elastomeric Bitumen). Parafor Solo GFM has a F.AB fire rating and is Factory Mutual approved.  Parafor Solo GFM achieves a ‘resistance to damage’ rating of R4 (the highest level of acceptance) under MOAT 31.  Parafor Solo GFM cap sheet has a F.AA fire rating and is Factory Mutual approved.


Long term solution, life expectancy in excess of 30 yrs.


Proven Technology: original SBS elastomeric bitumen membrane system.  Rapid installation, loose laid, with mechanical fixings along the laps which is secured by torching.  Parafor and Paradiene membranes are covered by a BBA Agrément Certificate.


  • System carries a 20 year independently insured guarantee for both materials and workmanship.
  • Can only be installed by approved contractors to ensure product quality is maintained
  • User friendly, quick and easy to install.
  • Full range of accessories/supporting products, all included under a single comprehensive guarantee, includes: rooflights, `refurbishment outlets, vents, lead-free flashings, edge trims etc.
  • All Langley elastomeric membranes have been developed in accordance with the European Union of Agrément (UEAtc) and are manufactured and tested in accordance with UEAtc MOAT special directives (Methods of Assessment and Testing).

Holistic Package

For users peace of mind, this system is supported by the full Langley package that includes: surveys, condition reports and proposals, specifications, site monitoring and reporting, technical and design advice, guarantee inspections, all at no additional cost.

The above information is issued in good faith and without warranty and is intended as a guide only. The information comprises typical data and does not constitute a specification.