I am looking for a clear intumescent coating for external cladding boards. The cladding is Marley Cedral board, a fibre-reinforced cement plank. The factory-painted product has an A2-s1, d0 reaction to fire classification in accordance with EN 13501-1 However to meet building regulations it requires a 30 minute fire resistance. Do you have a product that could be applied to the external surface which would give it that level of fire resistance? Thanks.