After a competitor, incorrectly specified a bitumen material which was left uncovered and failed after being exposed to chemicals used in UPVC door manufacturering, Koster UK were asked to provide a solution. The surface was thoroughly cleaned to remove the bitumen coating. The clean surface was prepared with Koster Polysil TG500 and NB1 was applied along with Repair Mortar Plus fillets. Koster SL Premium was used to provide a strong level surface to accept the Koster LF-VL coating on the floor and EM-VS on the upstands.