After the British established a settlement near the mouth of the Singapore River in 1819, building construction in Singapore changed. The new settlement was small but very urban. Merchants built warehouses right next to each other along Boat Quay. Risk of fire became a problem because the buildings were so close together and had many valuable goods inside. Builders switched to brick masonry with clay tiled roofs, to reduce the fire hazard. Bricks and tiles were made at kilns on the island, and the mortar and plaster was made by grinding up corals from sea around Singapore.