FM Approved for PV roofs: what 4470, 4478, 4482 and 4484 tell you

Keep product, system and project apart

FM Approvals tests and certifies products and systems according to its own test standards. A certification is therefore a specific piece of technical information. It is neither a governmental building approval nor an automatic insurance commitment for every building. ^[1]

With roofs, the assignment of components is particularly important. An approved board and an approved roof membrane do not, merely by combination, produce any approved build-up. The selected construction and its conditions must match.

4470 and 4478: think roof build-up and PV together

FM 4470 is an important reference for roof covering or roof assembly systems. FM 4478 addresses rigid PV modules in connection with roof assemblies. Which evidence is required in a project depends on the intended application and the requirements of the parties involved.

RoofNav helps in researching documented roof constructions. Record the specific system assignment including components, fixing and scope of performance, instead of just passing on a general download folder. ^{[1] [2]}

4482 and 4484: place coatings in the right scope

FM 4482 concerns roof maintenance coatings; FM 4484 addresses protective coatings associated with PV. The stated scope, substrate and assembly determine what an approval covers. Approval for one application does not establish another. Check the current Approval Guide entry and its supporting report. ^[3]

What to check in the system listing

Record the system number and document revision. Then compare the membrane, insulation, layer thicknesses, fixing and PV layout with the proposed roof. Include substrate restrictions and application rates in the specification.

If a component is absent from the listing or your build-up differs, submit that specific change for technical assessment. This establishes whether the variant falls within the documented scope or needs additional justification. ^{[1] [2]}

Which alternatives to the specified construction are possible

Some project specifications name preferred systems but permit technically justified alternatives. An alternative solution is then assessed against the required protection objective and suitable evidence. Material class, fire resistance and project acceptance remain separate levels.

The guide to insurer requirements shows how to set out the tested reference build-up and your alternative clearly side by side. The goal is a specific decision about the roof, not a collection of as many logos as possible.