Home Remodeling Basics: Planning from House Foundation and Surfaces
To a first-time remodeler the anatomy of a house may seem overwhelmingly complex, but actually it’s not that complicated or difficult to understand. Standard building procedures vary only slightly throughout the country. After examining the overview of your house, you’ll have a good idea of how most homes are built. At this point you will be able to walk through and assess your home.
In many ways the structure of your house is like the structure of your body. The skeletal frame provides strength and support. Hidden within the frame are such essentials as electrical, plumbing, and heating systems. The exposed surfaces of the frame and systems are protected by various skins, such as roofing, siding, and wall coverings. Inspect the anatomy of a typical house from the ground up starting with the foundation.
Most homes rest on concrete footings that transfer the weight of the house to undisturbed soil beneath the frost line. Above the footings is a foundation wall, which elevates the house above the ground to prevent decay and damage from moisture and insects, especially termites. If your home has no basement or crawl space, the foundation and footings are generally poured together in a single concrete slab. This would lead one to the structural framework.
The wooden framework above the foundation forms the skeleton of your house. Two basic types are used: post-and-beam construction and platform framing. If the type of framing in your house isn’t evident from the interior, you will be able to identify it in the attic, basement, or crawl space.
Post-and-beam construction was the main type of building until the late nineteenth century, and it’s still popular in areas such as New England. Post-and-beam consists of a framework of vertical supports (posts) connected by horizontal spanning members (beams). The wooden timbers are large, perhaps 4 by 12 or 6 by 12 inches. Often the framework is exposed in the interior of the house and easy to identify. Walls between the wooden framework divide the interior space but aren’t an essential part of the structural system.
Platform framing has been the predominant type of wood construction in the last 80 years or so. A variation called balloon framing is common in some older homes. Instead of a few massive pieces that support a post-and-beam structure, platform framing employs many smaller pieces of lumber. Each floor is a platform or box that sits on top of the previous floor or platform.
Most homes in the United States today were built with this method, which is the type of construction referred to universally by most contractors. Even if the exterior of your home is brick or masonry veneer, the inner structure is probably wood that is platform-framed.
The dimensions of wood used in platform framing have changed over the years. You should keep these slight differences in mind when you plan your remodeling. If you own an older home, for example the wood may have un-planed surfaces and a rough, almost fuzzy appearance. Those 2 by 4s may measure a full 2 by 4 inches, but in recent years lumber sizes have become smaller.
What about floors? If your home has a slab foundation, the concrete functions as the main platform for the house. If your home has a basement or crawl space, floor joists and subflooring provide a solid platform for holding up the rest of the house. The joists span the width of the basement and overlap over a main beam called a girder. Normal spacing between the joists is 16 inches from center to center, which is often abbreviated o.c., on center.
The type of subflooring nailed to the joists depends on the age of your house. If you have an old home built before 1950, it’s likely that boards laid across the joists, either diagonally or perpendicularly, form the subfloor. In much more recent homes, subflooring is either a single layer of plywood or a double system of plywood and hardboard.
Walls are a slightly different story. Both the exterior and interior walls of your home are framed with vertical studs nailed 16 inches on center between a bottom plate and two upper plates made from 2 by 4s. The framing is normally 2-by-4 lumber, but there are exceptions. For example, the first floor of a three-story house and newer homes built in cold climates may have 2-by-6 exterior walls. Also, the framing of one wall in your bathroom, called wet wall, may be wider than 2 by 4 to accommodate large drain pipes.
A word of caution: you may find odd spacing between the studs in your home. Don’t assume conventional spacing until you’ve actually checked the walls you’re going to work on.
All exterior walls and some interior walls in your house are bearing walls. This means they are a principal support for the weight of the roof and floors above them. A bearing wall transfers its load to the ground through the foundation or through a girder and posts. The nonbearing or partition walls in your house do little but divide the interior space. They support only the weight of the materials nailed to their surfaces.
In general, nonbearing walls can be easily removed without affecting the structural stability of your house. Bearing walls cannot. To remove a bearing wall you must provide a permanent alternative means of support, such as a beam and posts.
What is to be made of ceilings? The ceiling joists in your home provide a nailing surface for the finish ceiling and add stability to the framing by tying the exterior walls together. If your home has two stories or more, the ceiling joists for the lower levels are also the floor joists for the upper level. The framing procedure is simply repeated to complete another story, or platform. Once the top floor is reached, roof rafters are nailed in place, and the structural framework of the house is complete and one can move on to exterior surfaces.
The exterior surfaces of your home add stability to the structure and form a protective skin that covers the framework. It is advised to visualize your home’s roofing as three layers: wood sheathing or decking nailed to rafters; building paper; and a finishing roofing material such as shingles, shakes, tiles, or tar and gravel. In some cases the local building code determines which roofing finishes you can use.
The exterior walls of your house can be summarized in a similar way: wood sheathing nailed to the outside of the studs, followed by a layer of building paper, and finally a finish siding material, such as wood, vinyl, aluminum, stucco, or brick veneer.
Depending on the climate and the age of your house, the cavity between the exterior sheathing and interior wall surface may be filled with insulation. Fiberglass batts or blown-in fill are commonly used.
Most interior walls and ceilings in your home are covered with one of three materials: lath and plaster, wallboard, or wood paneling. If your home is very old built before the 1950s, the walls and ceilings are probably lath and plaster. Lath is thin strips of wood nailed directly to the studs and ceiling joists, over which several coats of plaster are applied.
If you have a newer home, the walls and ceilings are probably panels of wallboard, a sandwich of �½-inch gypsum between two layers of heavy paper. Wallboard is also called drywall and gypsumboard. The type of wallboard finish depends on the function and d�©cor of the room. Your house may have some wallboard surfaces that are painted or wallpapered, while others are first covered with a skim coat of plaster and then finished.
Wood paneling can be individual boards or large panels. If your home has boards applied in a horizontal pattern, they are probably nailed directly to the studs. If the boards are applied vertically, a system of wood strips called furring is nailed to the studs first to provide a nailing surface for the boards.
If the paneling is applied in 4 by 8 foot sheets, it’s made of plywood. Thin panels nailed directly to the studs tend to ripple and have a hollow sound. The usual method of application is to nail wallboard to the studs and then nail and glue on the paneling. The interior wall covering completes the basic structure of the house.
