Carpentry & Building ConstructionChapter 15:
Floor FramingChapter SummariesSection 15.1 Floor Framing Basics
Girders, supported by wood or metal posts, are often used to support floor systems. Floor trusses can be used as girders, or as joists when long spans are required. Section 15.2 Framing with Joists & Girders
Floor joists are commonly made of solid lumber or I-joists. Rim boards should be used instead of rim joists when the floor is assembled with I-joists. Special framing techniques must be used for large openings. Cross bridging improves the stiffness of joists. Girder floor framing is often used with a crawl-space foundation. Section 15.3 Subfloors
The subfloor consists of plywood or OSB panels applied to joists or girders. In some cases, underlayment plywood is applied over the subfloor.  | 
