To receive a “Certificate of Occupancy” and move in to your new orremodeled home requires that Building Code specifications have been met. When it comes to windows and doors, these requirements often include terms like “egress”, ”tempering” and “DP ratings” that may be unfamiliar to you.
“Egress” is the window size dictated for bedrooms with window-only access to the outside. This size is specified in Building Code and ensures that not only can you escape in case of fire but also that firefighters or emergency personnel can enter. All bedrooms are required to meet egress guidelines.
‘Tempering” is a glass treatment that causes glass to break in small chunks rather than long, highly dangerous, shards. Windows that are adjacent to stairs, landings or water sources may require tempering. In addition, high or large windows may require tempering. North Carolina Code specifically outlines the applications that require tempering. All doors with glass require that the glass be tempered.
A “DP” or “design pressure” rating is a numerical value given to a building component that represents its ability to withstand a given amount of wind load. DP ratings represent three performance elements which include structural load, water resistance, and air infiltration resistance. A higher DP value indicates a window or door that can withstand more wind, water, and/or structural load than a window with a lower DP. The DP rating required is based on the elevation of your building site which, based on research, has been assigned a wind rating.
Meeting these specifications is required by North Carolina Building Code.The following portion of the Beech Mountain City Code illustrates these requirements:
Installation of windows and doors (that are of proper DP RATING and found to comply with the solar heat gain co-efficient minimum rating of 0.40 or less) must be inspected to ensure that manufacturers specifications have been followed … Labels on windows must not be removed until inspection has been completed. Tempered glass in areas that are listed in the code as hazardous locations will also be inspected at this time.
Solar Heat Gain and other specifications may be dictated by local codes, but egress, tempering and DP rating requirements are virtually universal.
Code requirements ensure your safety and protect the current and future value of your home. Feel free to call us or ask your builder for more information about this critical issue.
2012 NORTH CAROLINA DESIGN PRESSURE REQUIREMENTS
Figure 301.2(4) – BASIC DESIGN WIND VELOCITIES FOR MOUNTAIN REGIONS
The 2009 footnotes to the mountain wind velocity table have been eliminated and the mountain wind speeds for 2012 are based on first floor finish elevation as follows:
Less than 2,700 feet
2,700 to less than 3,000 feet
3,000 to less than 3,500 feet
3,500 to less than 4,500 feet
4.500 feet or greater
90mph 100 mph 110mph 120 mph
90 mph= DP 20.217
100 mph= DP 24.96
110 mph= DP 30.201
120 mph= DP 35.942
130 mph= DP 42.182