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Know Your House: What Makes Up a Floor Structure

by Bud Dietrich

Once the foundation, or substructure, of a house is in place, the next step is to build the superstructure: floors, walls and roof. Among all the available building materials, wood is the most commonly used in North America, so that's where we'll start.

Why Wood?

Wood is a top building material for several reasons. One is tradition: Historically, North America was sparsely populated, and old-growth forests were abundant throughout the continent. Wood can also be easily processed into posts, beams, floor joists, roof rafters and other components of a house's structure. Furthermore, while a skilled carpenter can work wonders with wood, it's possible for a novice to build a small house of wood.

The great innovation in wood framing came about in the early 19th century with the industrialization of North America. Harvesting trees became more efficient, as did processing the trees into dimensional lumber that could be used for framing. Sawmills large and small sprouted up wherever there was a forest and a way to transport the felled trees, such as a waterway.

Alongside the mass production of framing lumber was the development of mass-produced nails. No longer hand forged onsite or nearby, nails became common and inexpensive. Between the mass production of dimensional lumber and nails, the wood-frame structure became ubiquitous, and the iconic carpenter with a hammer in hand, tool belt filled with nails and maybe one in his mouth, became the symbol of American home building.

Here's how carpenters build the first stage of a home's aboveground structure: the floor.