Codes for Building Wood Decks in South Carolina

Decks Requiring Permits

• Generally, the county governing authority needs to issue a building permit before any additions or renovations to existing structures can be made. According to the International Building Code, decks less than 400 sq. ft. and less than 30 in. off the ground do not require a permit. However, this requirement may vary by county. For example, in Pickens County, decks less than 200 sq. ft. and less than 30 in. off the ground do not require a permit.

Wood Requirements

• Fire-retardant wood is a requirement when building decks. Second-hand wood and materials are possible if they meet the standards of Section 17 of the South Carolina Building Code. The wood should be pressure-treated according to the size of the timbers. Since pressure-treated wood may corrode, builders must use galvanized fasteners.

Foundation and Soil

• As with all structures, soil and frost conditions affect decks. According to Casey's Building and Remodeling, the frost line in the Charleston, SC area is 24 inches. A concrete pier should be placed below the frost line with a support post of pressure-treated lumber attached to the concrete pier. In Oconee county, adding a deck with joists or headers more than 6 feet to a mobile home requires a special permit that must comply with the South Carolina Residential Builder's Commission.

Railings and Supports

• According to the International Building Code Sec 16.02, exterior floors of decks must be supported on at least two opposing sides by an adjacent structure, posts or piers. Many accidents are due to weak railings or railings that children can climb. Railings are a requirement when decks are further than 30 in. from the ground. They must be at least 34 in. high with supports, or balusters, no more than 4 in. apart.

Nails and Staples

• According to the International Building Code 2303.6, nails and staples must conform to the requirements of ASTM (American Society for Testing and Materials) F 1667 for wood structures, including decks. Nails used for framing and sheathing must have minimum bending yield requirements that vary according to the nail shank diameter.