AllShield BarrierSheet in FM Approved roof assemblies under FM 4470

AllShield BarrierSheet is included in specified FM Approved roof assemblies under FM 4470 and Approval Report PR472014. For commercial roof projects, this provides recognised system evidence for defined roof constructions rather than relying only on individual material properties.

What FM 4470 covers

FM 4470 is the Examination Standard for Single-Ply, Polymer-Modified Bitumen Sheet, Built-Up Roof (BUR) and Liquid Applied Roof Assemblies for Use in Class 1 and Noncombustible Roof Deck Construction.

Approval Report PR472014 includes AllShield BarrierSheet within the applicable roof assembly. The relevant construction is listed through FM RoofNav, where the components and system conditions that form part of the approval can be checked.

This is particularly relevant on commercial roofs because fire performance is only one design constraint. Structural capacity, waterproofing, insulation, wind resistance and future rooftop equipment all need to be resolved within the same roof build-up.

Low added weight within the roof design

At approximately 3 kg/m², BarrierSheet adds relatively little permanent load. This can be important where the available structural reserve also needs to accommodate PV, additional insulation or other rooftop equipment.

The value is therefore not simply the addition of a protective board but the ability to incorporate passive fire protection within a roof design where weight remains a critical constraint.

Existing roofs require an assembly assessment

On a refurbishment project, the retained roof remains part of the design. Deck, insulation, attachment, waterproofing and other existing components therefore need to be compared with the applicable RoofNav requirements when an FM Approved solution is required.

This makes early assessment particularly valuable. The owner can determine whether the intended roof refurbishment and future PV system can be accommodated within the required structural and approval framework before the project is committed.

Relationship with FM 4478

BarrierSheet is also included in a specified RoofNav roof-PV assembly under FM 4478. Where PV is planned, considering the final roof-PV use from the start can prevent conflicts between the roofing specification and later PV or insurer requirements.

FM Approval gives insurers a recognised basis for assessing the roof; acceptance always depends on the complete assembly and the project-specific risk assessment.

For FM projects, consult the current RoofNav listing and Approval Report PR472014 before fixing the final specification. AllShield can assist project teams in identifying the applicable BarrierSheet assembly.