There are four basic material options for long spans

Engineered wood, also called composite wood, man-made wood includes a range of derivative wood
products which are manufactured by binding together the strands, particles, fibers, or veneers of wood,
together with adhesives, to form composite materials. These products are engineered to precise design
specifications which are tested to meet national or international standards.   Typically, engineered wood
products are made from the same hardwoods and softwoods used to manufacture lumber. Sawmill scraps
and other wood waste can be used for engineered wood composed of wood particles or fibers, but whole
logs are usually used for veneers, such as plywood.

Advantages of engineered wood:
  • Because it is man-made, it can be designed to meet application-specific performance requirements.
  • Large panels of engineered wood may be manufactured from fibres from small diameter trees.
  • Often stronger and less prone to humidity-induced warping than equivalent solid woods

Disadvantages of engineered wood:
  • They require more primary energy for their manufacture than solid lumber.
  • The required adhesives may be toxic.
  • Cutting and otherwise working with engineered wood products can expose workers to these toxins