TEXTILES.ORG
The following roof systems offer different advantages and cost levels.
Modular: A green roof with drainage layers, filter cloth, growing media and plants already prepared in movable, interlocking grids.
Loose laid: Same as modular, but the grids are not necessarily interlocking.
Built-up: A green roof comprised of individually constructed layers, including waterproofing, drainage board, root protection barriers, soil and plantings.
Intensive: A green roof with deeper soil media (8”–30” in depth). These roofs are typically comprised of diverse plant material, accessible to users and higher cost than extensive systems.
Extensive: A green roof with shallow soil media (2”–6” in depth) that are typically comprised of sedum plants, inaccessible to users and lower cost than intensive systems.