Wood Frame Residential Construction

Wood is the most commonly used building material in residential homes. There are several methods of framing but we will consider the most predominant which is platform construction. The foundation of modern residential homes are either poured concrete or cement block. Footings are installed under all of the foundation walls to transfer loads to the soil. Footings should be deep and wide enough to adequately spread out the loads of the structure to limit the potential for settlement. The house foundation supports the entire weight of the structure. The depth of the foundation is determined by the type of soil and the frost level in the area of the building. Homes can also be constructed on a slab foundation which is a support method that does not have a basement or crawl space.

In the platform framing technique, the floor structure is secured to the sill plates which are attached to the top of the foundation walls. The floor joists, usually 2 inch thick members 8 to 12 inches wide, are secured at the ends by a rim joist or box plate. There are usually smaller framing members called bridging that are secured in between the joists to help keep the joists from twisting or moving. Often joists are doubled up to accommodate openings such as stairwells. The doubling up provides more structural rigidity to the openings or passages. The sub flooring material which is usually plywood is installed on top of the joists and then the finished flooring materials are installed on top of the sub flooring.

The walls of the frame dwelling are built by nailing wall studs to top and bottom plates or frame members. The walls are then lifted and fastened to the floor structure. If the wall is load bearing a two member built up top plate is used for added strength and to increase the load bearing capacity.  When doors and windows are installed headers are used to support the weight of the structure above the opening. The exterior of the walls are covered with sheathing usually plywood or oriented strand board (OSB). The other levels of the home come together in a similar fashion.

The roof rafters are installed onto the top of the house walls and are joined together at the ridge board or beam which will be the peak of the house. The rafters will make an triangle pattern as the roof structure comes together. Sheathing, usually plywood or manufactured decking, is attached to the rafters, this will become the roof deck. The roof deck is then covered with the appropriate felts and ice shields. The roofing shingles (usually asphalt tab) are nailed to the roof decking on top of the felts and ice shields.

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