FRAMING

The most common materials used for residential construction are wood and concrete. Most homes have a combination of both. In this section, we will look at some of the details of wood frame construction.

There are many framing styles used for residential homes, but the names for many of the various structural components are essentially the same. If you know of a house that is in the framing stage of construction, try to visit the site and see how many of the structural components you can identify. Of course, be sure to obtain permission from the owners/builders.

An important characteristic that all the designs have in common, is the use of the triangle. As you may have learned as early as grade school, triangular structures are rigid because the shape of a triangle cannot change without changing the length of its sides. Consider the two frames shown below. For simplicity, assume the structural components (struts) are connected at each vertex with a single nail. When external forces are applied in any direction to the triangular structure, the forces generated at the vertices will be shear forces. Provided the members themselves are sufficiently strong, the nails would have to be sheared for the structure to fail.

Framing is one of the most exciting phases of the construction process. During the framing phase you will watch the house take shape. Most people get very excited when the framing is done, thinking that the house is almost built. In reality, the house is only about one-third complete.

The framing must be accurate. If the framing is poor quality, the drywall won't be flat, the floors will squeak, and doors will not close correctly. The job of the general contractor is to make sure the framers follow the plans and the building code.

In traditional platform framing a platform or floor is built on the foundation. The structure is bolted to the foundation with anchor bolts and hold down straps. Walls are placed on top of the floor joists, followed by the roof trusses Traditionally, the floor joists are made of 2x8 - 2x12 boards. However, today the best choice for floor trusses are composite "I" beam joists. They are environmentally friendly using up to 60 percent less wood to make than a solid wood joist and are straighter, stronger and lighter than traditional floor joists.

The subfloor made of 3/4 inch OSB or plywood is attached to the joists with nails and glue to prevent squeaks later on. Using screws instead of nails is highly recommended.. The walls are built of 2x4 studs (2x6 exterior wall are an option). Studs, top and bottom plates, headers trimmers and cripples form the walls (click on graphic above). The interior of the walls will be covered with drywall and the exterior walls with 7/16 inch sheathing (OSB or plywood).