Q&A: Polystyrene foam alternatives

Q

I found out from a friend that most of the expanded polystyrene used in building in Australia probably contains a brominated flame retardant—likely HBCD or DBDE—and that these are being banned in Europe because they are persistent, toxic chemicals.

We are about to build a sustainable house but don’t want to use something that’s both toxic to people and persistent in the environment.

Apparently these flame retardants are not used in polystyrene used in food packaging (phew!) but a flame retardant is required in all commercial building polystyrene.

I’ve called a few companies and they have trouble telling me what the exact chemical is. I’ve found that they import their beads from China already coated in the retardant, and then expand them here. Apparently the flame retardant is just a coating on the beads and not part of the chemical structure, so it can come away once installed, and end up in dust or in the air.

Are you able to tell me if anyone at ATA has looked into this and could you recommend a supplier that doesn’t use a brominated flame retardant? I’d be a willing customer!
—Linda Meisel

A

We are not aware of any polystyrene foams for building that use fire retardants that are not brominated. According to the US EPA publication 740R14001, Flame Retardant Alternatives For Hexabromocyclododecane (HBCD—Final Report, June 2014 (www.bit.ly/FRAFH14), “No non-brominated flame retardants are known to be compatible in polystyrene manufacturing and associated flame tests.”

There are other products that are naturally fire-resistant and so don’t have added fire retardants, such as hempcrete, timbercrete, AAC (Hebel) and similar naturally derived building materials. Insulation materials such as glass and mineral fibres are naturally flame retardant. I used Knauf Earthwool insulation in our home here; it is naturally non-flammable and the fibre binder is based on plant starches.
—Lance Turner

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