Many structural components make up a house, but three are arguably the most important: the foundation, the walls and the roof. Everything else depends on those three. Walls stand on the foundation and support the roof. Here’s what you need to know to be an informed homeowner.
Materials. Wall frames are constructed out of lumber, metal studs or concrete blocks. The metal frame may be used in areas where termites are of particular concern and the concrete walls along the southern coasts where hurricanes are a threat. Otherwise, the most likely material for the wall frame is pine lumber.
Each wall is typically assembled lying flat on the ground, then raised to standing and nailed to the floor. On the ground floor, the bottom piece of lumber that lies on the concrete foundation is called the sill plate. It is made of treated wood to be water resistant. It is attached to the concrete with special nails that can penetrate the wood and the concrete below, using an extra powerful nail gun called a ramset to make sure that the plate is securely attached.
The vertical studs are made of regular 2-inch by 4-inch lumber and each piece is usually spaced “16 inches on center,”which means that measuring from the center of one to the center of the next will be 16 inches. Overhead, the completing horizontal piece spanning the vertical studs is called the top plate.
Other materials and support. Outside walls need bracing to strengthen them in case of wind. Otherwise strong winds could cause the house to lean, which can lead to major structural damage. To prevent this from occurring, the outside of the wall frame may have plywood or particle board cut to fit the shape and nailed to it. Alternatively, cross bracing may be attached over several of the vertical studs at a 45-degree angle. A thermal wrap and moisture barrier will cover the outside of the exterior wall in order to provide air and water protection. Then, outside masonry or siding is the final cover for the exterior wall. Finally, from the inside of the exterior wall, insulation will be installed and any plumbing fixtures will be wrapped with foam insulation.
Wherever a window or door is placed in a wall, a wider, stronger piece of lumber called a header beam is installed to provide extra support for all the weight above it.
Walls that support the extra weight of the floor or roof trusses above it are called load-bearing walls. Walls that run through the interior of the home but don’t provide main support for the structure above them are non-load bearing.
Finishing the inside of all walls will be some sort of panel, typically sheetrock. Sheetrock is made of gypsum and is inexpensive, provides good sound buffering between rooms and is easy to hang decorations on. Other materials, such as wood panel, or the shiplap made so popular on home improvement TV shows, can be used.
Throughout the house, electrical, plumbing and gas lines will be threaded through the insides of the walls to electrical outlets, and plumbing and gas fixtures.