POST AND BEAM CONSTRUCTION PLANS FOR DETACHED POLE BUILDINGS and CARPORTS, etc.
480 Square Feet Maximum
The NC Residential Code does not provide prescriptive plans for post/beam type structures as it does for conventionally framed structures. Consequently, this type of construction requires an engineered design in order to conform to the Code .
In order to alleviate the inconvenience and expense of this procedure for small, detached, and unoccupied structures, Gaston County Building Inspections is allowing, as an approved alternate method of construction, the following prescriptive details which, if followed, will be considered by this department as being acceptable under the NC Building and Residential Codes.
1. See Detail # 1* - Maximum overall size shall be 480 sq. ft.
Maximum length= 24’ Maximum width = 20’
2. See Detail # 2* - Footings shall be at least 24” deep by 16 inches square or 18” diameter round with 3000 psi concrete.
An 8X16 solid block is required at the bottom of the post.
3. See Detail # 3* - Posts must be minimum 4X4 factory pressure-treated lumber.
Maximum height of posts is 8’ measured from the top of footing to bottom of girder. Heights from 8’to 12’ require 6X6 posts. Heights beyond 12’ require engineering.
4. See Detail # 3* - Girders shall bear completely on posts and be fastened with a listed post/beam connector, or attached to the side of the post with two 5/8” diameter hot-dipped galvanized through bolts.
Pressure Treated 4X4 knee braces shall be attached to the girder and to the post at least 30” down from the girder at an angle of between 45 and 60 degrees using ½”X 8” lag bolts.
5. See Detail #4* - Header and girder sizes are determined from Table 502.5(1) of the 2009 NC Residential Code
6. See Detail #5* - Enclosed post/beam structures require horizontal girts at at 24” o.c. with the siding material attached to the girts. They are also required to have a closeable door.
*Access this link for details: Post and Beam Construction Plans