Fire Protection for Timber Frame and Spray Foam
Timber frame and spray foam insulation bring real performance benefits, but both are combustible and need careful fire protection to satisfy building regulations. An intumescent coating is one of the most practical ways to upgrade their reaction to fire on site.
Why timber and spray foam need fire protection
Exposed timber and polyurethane spray foam can contribute to fire spread. Left untreated, spray foam classifies only to Euroclass E under BS EN 13501-1, and exposed structural timber needs protecting where it forms part of the fire strategy. In both cases a tested, documented coating is the route to compliance.
What the regulations require
Approved Document B governs fire safety, and materials are judged on their reaction to fire under the European classification system (BS EN 13501-1), from A1 (non-combustible) down to F. The old “Class 0” national class has been superseded by Euroclass for most purposes. The practical aim is to move a combustible substrate up to a recognised, certified classification — backed by a test report you can hand to building control.
The solution: an intumescent fire-retardant coating
FRED is a liquid-applied intumescent coating for timber and spray foam. In a fire it swells to form an insulating char that slows heat reaching the substrate. FRED is certified Class A2-s1,d0, and has been fire tested by Warringtonfire on 11mm OSB, where we rate it at 15 minutes fire protection — a deliberate safety margin below the tested result.
FRED + Passive Purple: a Class B fire-rated airtight system
Applied over Passive Purple, FRED forms a combined system classified Euroclass B-s1,d0 (on A1 substrates with a density of at least 653 kg/m³) — delivering airtightness, vapour control and certified fire performance in one system rather than three separate layers. See Passive Purple Fire Performance for the details.
How it is applied
- Used internally, spray-applied with an intumescent spray machine to the specified wet film thickness
- For external use, overcoat with a fire-rated flexible coating such as Passive Purple External
- Available in natural, white and grey
- Low-VOC, so suitable for occupied and sensitive buildings
Benefits
- Class A2-s1,d0 certified on its own
- 15 minutes fire protection on 11mm OSB (Warringtonfire tested)
- Euroclass B-s1,d0 as a system with Passive Purple
- Works on timber frame and spray foam
- Documented test evidence for building control
Frequently asked questions
Does it replace fire-rated plasterboard? It is a reaction-to-fire coating for the substrate; always follow your fire engineer’s strategy and the relevant test scope.
Can it be left on show? Yes — see our white intumescent option for a clean finish.
Learn the basics in Intumescent Paint Explained, or talk to our technical team.