building were limited to brick, stone, timber and steel to form structures, slate and tiles for roof coverings, lead and sometimes copper for waterproofing details and decorative roofing effects. The Romans used concrete, but it was virtually unknown as a building material until the invention of reinforced concrete in 1849. Modern construction is much more complex, with walls, floors and roofs all built up from many elements to include structure, insulation and waterproofing often as separate layers or elements.

Architectural technology in practice