A. Lateral loads are the result of forces created by an earthquake shaking a structure or wind blowing against the sides of a structure. In general, lateral loads are considered to act horizontally, whereas loads resulting from the force of gravity are considered to act vertically.
A. It is important to build a structure to stand against both gravity forces (snow and the weights of materials, furnishing, and occupants) and lateral forces (earthquake and wind). Lateral bracing reinforces the structure's ability to stand against earthquakes and high winds.
A. The International Code Council (ICC) develops code requirements through a consensus-based process and publishes model building codes. Anyone can propose additions or changes, but ICC voting members decide what becomes part of the code. States and local jurisdictions often modify those codes to address unique factors in their areas.
A. No, wall bracing requirements vary to accommodate different levels of seismic activity and wind speeds across the country. Check with your local code enforcement agency to find out what the requirements are in your area.
A. Braced wall segments are reinforced sections of wall within a single wall line. Each type of braced wall segment has minimum size and spacing requirements as defined in prescriptive codes, such as the IRC. Proprietary prefabricated products such as the iLevel® Shear Panel and iLevel® Shear Brace may be installed instead of a site-built braced wall segment. A braced wall line is an imaginary line with braced wall segments along the line or offset not more than 4' from it.
A. Bracing is required at or near the ends of walls and every 25' on center in wall lines spaced not more than 35' apart. Typically this requires exterior walls to include braced wall segments and an occasional interior wall depending upon the house's dimensions. Premanufactured bracing may be required in areas with large openings. For example garage doors, large windows or sliding glass doors, and walls with many windows.
A. Bracing requirements, often specified as a percent of the overall braced wall line length, are based on a number of factors including the seismic design category, wind speed, number of stories in the structure, story height, and location relative to other stories. There are further modifications to the amount of bracing required based on such things as the size of openings within a wall line, braced wall line spacing, the use of stone or masonry veneer, and wall heights. To determine bracing requirements for a specific project, contact your design professional or call your iLevel representative.
A. There may be enough space to place a 48" wide OSB panel (IRC bracing Method 3) between the doors and windows to meet bracing requirements. If there is not enough space, narrower alternate bracing methods exist for wall spaces between 28" and 42", depending on the wall height. Proprietary products like the iLevel® Shear Panel and iLevel® Shear Brace may also be installed between the doors and windows. The proprietary products may be as narrow as 12" and most replace one 48" section of wall bracing regardless of the product's actual width.
A. Bracing may be offset at corners and is dependent upon the Seismic Design Category (SDC). In SDC A, B or C, braced wall segments may be offset from the wall end by up to 12.5' and in SDC D0, D1 or D2 the maximum offset is 8' when certain conditions are met. To determine what offsets are permitted for a specific project, contact your design professional or iLevel representative.
A. No, braced wall segments may be offset up to 4' to either side of the braced wall line.
A. Yes, wall bracing is required on all stories of a structure. The amount of bracing for upper stories is generally less than the first story.
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