With attic trusses, it is possible to span wider distances onto exterior load-bearing walls, with regards to the dimensions in the space or desired span. All roofs have both a rafter or truss to maintain structural integrity. Historical and standard residences normally use rafters, while modern-day households use lightweight trusses. https://directoryorg.com/listings12933091/not-known-details-about-prefabricated-roof-trusses-installation