Building codes are one of those necessary evils that can be annoying at times but go a long way toward ensuring a safe house. Wall-building codes encourage uniformity and structural integrity. Local authorities ensure compliance by approving architectural plans before issuing building permits and by inspecting the wall framing before giving contractors the green light to hang drywall.

Standard Wall Framing Residential walls must contain minimum-dimension lumber. In most cases, this is determined not by the local building authority, but by the engineer or architect who draws the house plans. Standard 8-foot walls typically call for two-by-four wall studs, set 16 inches apart. The walls need a bottom plate and two top plates, cut from similar dimension lumber. Depending on the rest of the structure, the architect might alternately specify stud spacing of 19.2 or 24 inches.

Tall Walls As wall height increases, so does the need for a beefier structure. An architect might call for two-by-six wall studs instead of two-by-four studs when wall height exceeds 9 feet. The higher the wall, such as those found in vaulted entryways, the larger the required lumber dimensions. An architect or engineer can specify four-by-four posts every four feet or so to increase wall strength. Local building authorities generally defer to the house’s architect unless there is a disagreement. Because multiple parts of the structure must often be changed if one element is changed, it’s imperative to get the plan approved before starting construction.

Load-bearing Headers Load bearing walls follow the same building guidelines as non-load bearing walls except when it comes to framing door or window openings. Because these walls support the structure above, the contractor must install headers over door and window openings. The architect determines header size, which depends on the width of the opening and the amount of load above the wall. Jack studs support the header on either side and attach to full-length wall studs for additional support. If the load above the header is substantial, it’s not unusual for the architect to call for double or triple Jack studs.

Non-load Bearing Openings In non-load bearing walls, two-by-four lumber is usually sufficient for framing door and window rough openings. Cripple studs, which are cut to fit beneath a window rough opening and above both door and window rough openings, stabilize the framed opening.

Shear Walls In regions subject to high winds or earthquakes, local codes often require the construction of a shear wall that can withstand lateral pressure and movement. This can include minimum thickness sheathing, a pre-determined nailing pattern, horizontal or diagonal bracing between studs and the use of earthquake ties that give the wall additional strength.

Fire-rated Walls Walls that separate individual family living areas, such as apartment walls, or the wall between an attached garage and a house, are subject to additional fire codes. The intention is to slow the spread of fire from one side of the wall to the other. Regular drywall, made of gypsum, offers some fire resistance value, but to increase the fire-rating factor, thicker gypsum, or special fire-rated gypsum might be required in addition to fire-rated tape and joint compound. The necessary degree of fire-resistance is designated as one-hour or two-hour, referring to the time it should take for a fire to spread through the wall. When building a fire-rated wall, every opening must comply. Outlets and switches must be fire-rated and sealed with fire-rated caulking. All doors must also be fire-rated and installed to local fire code specs.

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