FOAMGLAS® in Warm Roofs

Sitting here looking at a large stock of FOAMGLAS® in the warehouse, it strikes me how much the insulation industry has changed since that fateful morning when we all awoke to the sights of the Grenfell Tower tragedy. Once the preserve of specific high-end applications, Cellular Glass insulation has become a much more widely specified thermal insulation in warm roof applications, and mostly not for regulatory reasons.

Yes, you need to use Cellular Glass insulation on specified attachments on buildings over 11m high, but you are not required to use Cellular Glass on a warm roof to achieve Broo(t4) fire regulation compliance in England, Wales, Scotland or Northern Ireland. Why then are we seeing such high demand for ‘Non-Combustible’ Cellular Glass insulation?

The answer is simple; it’s that some insurance companies, clients and specifiers are going for a ‘belt and braces’ approach and requesting Cellular Glass insulation simply for its reaction to fire class A1 ‘Non-Combustible’ status. But as we pointed out in our February 2023 column, which we are sure all our avid readers recall, not all Cellular Glass products are rated class A1. Those with a factory laminated facer are generally class E, so it’s a case of Caveat Emptor (buyer beware) when you are specifying or ordering your Cellular Glass insulation.

Another consideration is how you are going to install the FOAMGLAS®. It can be bonded in a number of ways depending on the specification you are using: 

• Hot charge 95/25 bitumen using either the Bitumen Coating method or the Pour and Roll method.

• Proprietary adhesive such as PC 56 or PC 58 cold bitumen adhesive, PC 800 one-component polymer adhesives, or PC 11 cold bitumen adhesive specifically for bonding READY BOARD onto profiled metal roof decks.

• Moisture Curing Polyurethane. 

Whichever method is used, the site teams are going to need appropriate health & safety equipment and some more unusual tools for roofers – hand sanders and hand rasps. Cutting the FOAMGLAS® with a suitable hand saw can be done as with most other insulations, but the hand sanders and hand rasps help enable trimming of the FOAMGLAS® to ensure close fitting of the boards.

Waterproofing wise, most generic types can be used including RBM, LAM, Hot Melt and Single Ply. Just check the compatibility of the FOAMGLAS® Cellular Glass Product specification with the waterproofing supplier before installing.

There are some really helpful videos on here:

Next month: High performance XPS