A swelling fire retardant paint / varnish is a surface treatment with the purpose of protecting the wood or plywood substrate against fire and ignition. The principle is that the applied paint layer swells up and forms a protective foam layer in case of fire. However, the fireproofing paint / varnish does not in itself change the wood's own properties against fire, but it is the outer layer of fireproofing paint that allows for the treated surface to reach the highest fire class.
For a material to be given the highest classification, all exposed sides and surfaces must be treated. This means that, for example, if wood panels are mounted at a distance (spaced boarding) with air gaps for acoustic dampening purposes, all sides of the wood panel must be painted. The same principle applies when using e.g. perforated plywood, where both the front, back, as well as each perforated hole must be coated.
Fireproofing paint is best suited for indoor use. Special properties are required for exterior application; it must therefore be specified for a treatment whether or not it is intended for outdoor purposes.
The method in short
- The purpose of applying fireproofing paint is that the coating should protect the wood (D-s2, d0) against fire and ignition.
- Wood and plywood do not in themselves have their own fireproofing properties, but it is the paint layer that protects the substrate.
- A film layer is formed on the surface.
- The fire-resistant surface layer only protects the surface that has been painted and is sensitive to wear and tear.
- Open construction, e.g. spaced boarding, requires painting of four sides.
- Mounting on plaster without air gaps requires painting of three sides.
- On-site application requires extensive control plan systems; such a control system has been developed by the Nordic Association for Fire retardant treated wood (NBT).
- The CE marking is only available for industrially painted products.
- CE marking according to EN14915:2013+A1:2017 is required by law.
- CE marking according to EN13986:2004+A1:2015 is required by law.
- A performance declaration for each specific product is required by law.
- Type-approval certificates are available, for which continuous production controls will be performed by the notified body (e.g. RISE).
- Type-approved and CE certified makes are available.
- Products painted on-site cannot be certified/submitted according to CE marking requirements or type approval certificates.
Certifications are available via the EAD 350865-00-1106 (which has replaced ETAG 028).