Envirograf, No-Burn, FlameOFF, and ProTek all manufacture intumescent coating systems capable of achieving FD20 fire-resistance ratings on timber doors [1][2]. These companies specialize in products that expand under heat to form an insulating char layer, the primary mechanism for meeting the twenty-minute fire standard.

However, purchasing a product from any of these manufacturers does not automatically guarantee FD20 compliance. The critical requirement is that the specific product must be tested and certified for the exact door construction, timber thickness, and application method being used. Compliance requires certification to BS 476 Part 22 or EN 1364-1 standards, and the manufacturer must provide a certificate of compliance or declaration of performance (DoP) that explicitly references the FD20 rating for your particular door assembly and substrate.

When selecting from these manufacturers, you must verify that the chosen product is an intumescent system rather than a generic fire-retardant paint that only reduces surface flame spread. Application must strictly follow the manufacturer's technical data sheet regarding spread rates and coat thickness. The safest approach is to request from the manufacturer: the exact tested door assembly configuration, the fire test standard used, the DoP or certificate of conformity, the required dry film thickness or coverage rate, and any restrictions on timber species or door thickness. The brand name alone is less important than the test evidence and technical documentation supporting the specific product for your intended use.