Floor Biomass access covers are manufactured from magnesium alloy as a flush or upstand roof cover. Biomass fuel doors can be operated either manually, hydraulically or electrically as a single or double leaf unit. The patent marine alloy frame incorporates a single or double unbroken EPDM seal to help prevent the ingress of dirt and moisture, offering water and near air tight seal. Vented, insulated and airtight options are available. Biomass covers can be supplied with mushroom vents, manufactured in stainless steel, the unique design prevents the ingress of rain or foreign bodies, while internal mesh stops deliberate interference and vandalism.