Most modern houses are framed with 2-by-4s or 2-by-6s.
Most houses today are framed using what is called "balloon framing." This term refers to house frames made of dimensioned lumber such as 2-by-4s or 2-by-6s, as opposed to the older method of timber framing with large, interlocking beams. Balloon framing became popular with the advent of centralized wood mills that produced lumber of standard dimensions in large quantities.
Stick Walls
Modern house walls are built by assembling parallel, vertically oriented studs that are connected at top and bottom by a top plate and a bottom plate. These studs are usually spaced at either 16 or 24 inches. 2-by-4 construction is common, although 2-by-6 construction has become more popular because it allows for thicker insulation and more heat retention in the finished house. Stick built walls can also be constructed using manufactured steel studs, and this is most common in large commercial construction jobs.
Floor Joists
Floors in modern houses are built by laying plywood over a grid of floor joists that are laid over the basement excavation. Floor joists are usually made of 2-by-12s laid on edge. The thickness of these pieces of wood creates a sturdy floor that doesn't bend or dip when people walk on it. Once the plywood has been nailed or screwed onto the tops of the joists, a solid floor is the produced that is resistant to buckling or movement.
Roof Trusses
Many modern houses are built with roof trusses that are made elsewhere and then transported to the house site. Roof trusses are rigid triangular units that can be installed in series on top of a house to support the roof. Trusses use geometry and engineering in place of material to create roof support that is just as strong as but uses less material than traditional rafters.
Headers
Headers are thick pieces of wood installed horizontally over the spaces for doors and windows. The purpose of a header is to transfer the weight of the roof above down the sides of the door or window opening to prevent sagging and possible breakage of windows and doors.
