Building Codes in Northwest Arkansas

Even modest decks are required to meet building codes, and for good reason. An improperly constructed deck can be a safety hazard, eyesore, and can even devalue your home. That’s why every deck project completed by Northwest Arkansas Decks and Patios follows all required legal codes.

Most codes are based on the International Residential Code. Each local municipality provides a list of codes that are required for that particular city or town. We are sure to follow all of the codes of the Northwest Arkansas location that each client lives in. You can download a free PDF copy of “Prescriptive Residential Deck Construction Guide” published by the American Wood Council. The following information will help you to understand some of the more important code-compliant details.

Ledger Flashing

Ledger flashing must be positioned according to code – wrapping over the top of the ledger and under the building paper and siding – to prevent water from infiltrating between the ledger and the wall. Many codes require flashing between the ledger and wall as well.

BeeM Overhangs or Cantilevers

These are strictly regulated by code and vary depending on the type of wood and thickness of the beam. Generally, the cantilever should not exceed 1″ in length for every 4″ of joist span. 

Post-Footing Diameter and Depth

This is essential for proper deck support. The requirements may differ slightly from one locality to another. However, basically, the most important aspect is that the footing is poured before the frost line. Which, in Fayetteville, Bentonville and throughout Northwest Arkansas, the frostline is 14 inches. The minimum footing diameter have become more stringent and now must be at least 12 inches. And in some instances are required to be 18 inches. The well-known 8 inch in diameter concrete tube forms are best reserved for fence posts.

Railings

Railings are required by local codes decks more than 30 inches above the ground and for most localities must be at least 36 inches tall. Bottom rails must be positioned with no more than 4 inches of open space below them. Balusters, whether they are vertical or horizontal, can be spaced no more than 4 inches apart.

Stairs

Stairs must be at least 36 inches wide, although 48 inch is preferable. Vertical step rises (or the height between each step up) should be no more than 7.75 inches. If left open, the opening must not be more than 4 inches. The treads should be a minimum of 10 inches deep. Northwest Arkansas Decks and Patios always strives to have exact an exact match with each tread. However, any variation cannot exceed 3/8 inches. The top of the railings should be 34-38 inches above tread nosing. And a grips are required for any stairs that have more than four treads. Finally, any stairs with more than three steps must have a landing area that is the full width  of the stairs and at least 3 inches from front to back.

Beams and Joists

Beams and joists must either sit on top of posts in an approved post cap, or be notched into a post that is at least 6×6 inches. Either 4×4 or 4×6 lumber can be used for posts 8 feet high or less (which is measured to the underside of the beam). Longer posts must be 6×6 inches. Joists cannot be attached to posts with through bolts, even when mortises have been cut into the posts. 

Deck Footing Sizes

Deck footing sizes vary and are calculated based on both the load of the deck and the makeup of the soil. Posts can be connected to footings with a post base hardware or sunk into the cement of the footings. Generally a post base is preferred because it can cause ground contact that can cause the post to rot.

Ledgers and Concrete Walls

Ledgers fastened to solid concrete must be attached with bolts and washers driven into approved expansion, epoxy, or adhesive anchors. Ledgers may not be attached to hollow block foundation walls. This is a fairly new restriction in many areas that previously allowed ledgers to be attached to hollow-block walls with lag screws driven into metal or epoxy anchors. 

Ledgers attached to Platform Framed Houses

Ledgers may be attached directly to the rim joist (which is also called the band joist) with galvanized lag screws or high-strength, self-tapping ledger screws driven in a staggered pattern. On larger decks, additional lateral load connectors often are required. These connectors secure the outer joists to joists inside the house via a threaded rod. If your home is built with floor trusses or with joists that are parallel to the rim joist, alternate connection methods are typically required.