(B) Material.
(1) All two-inch nominal dimension framing lumber shall be kiln dried standard grade or better and shall be identified by a grade mark. The grade shall provide adequate information to determine the “F” (Extreme fiber in bending) and “E” (Modulus of elasticity). Engineered systems shall be designed per § 150.171.
(2) Minimum sizes of lumber shall be construed to be nominal or dressed size as established by the American Lumber Standards Committee.
(3) Structural engineered wood products may be used in lieu of two inch nominal dimension framing lumber. The load design shall be as specified in § 150.171.
(4) When structural engineered wood products are used in floor and ceiling assemblies, they shall not be left exposed. Protection shall be provided by one of the following methods:
(a) A ceiling complying with § 150.201(A);
(b) An Underwriter Laboratory (U.L.). listed suspended ceiling assembly rated a minimum of one hour;
(c) An automatic sprinkler system designed per the current N.F.P.A. #13; Sprinkler Code, and approved by the Director of Community Development or his or her designee, and installed by an approved licensed plumber permitted to work in the city; and
(d) Other methods of equivalent protection acceptable to the Director of Community Development or his or her designee.
(5) Additionally, the area between the ceiling and the floor above shall be subdivided into areas of not more than 1,000 square feet with one-half inch type “X” drywall when utilizing structural engineered wood products.
(C) Framing.
(1) Wood framed walls shall be constructed of minimum two-inch by four-inch studs on 16-inch centers placed directly over and under floor and ceiling joist. Where air register boxes, heads, pipes or stacks are to be installed, joists shall not be set less than 12 inches on center and studs shall be directly over and under joists. When joists occur on 12 inches on center, they shall be continuous or shall have butted joints over a partition. Lap joints will not be permitted except where joists are on 16-inch centers.
(2) Wolmanized sill plates shall be not less than two inches by six inches and shall be securely anchored and tightly sealed to the foundation. Grouting will be required where structural support is necessary.
(3) Box sills or solid blocking of the same dimension as the floor joist height shall be provided at exterior walls.
(4) Sway braces shall be provided on each corner of all exterior walls.
(a) The braces may be one inch by four inch, let into the studs near each end of the wall. Such braces shall extend from the bottom to top plates at an angle not to exceed 60 degrees from the horizontal.
(b) The braces may be single plywood sheets located at or near each corner of the structure. The plywood shall be not less than one-half inch thick and four feet wide. The plywood material shall extend from the top to bottom plate.
(5) Headers supporting wood frame walls shall be not smaller than indicated in § 150.199.
(6) (a) Headers supporting two or more joist tails shall be doubled.
(b) Joist tails shall be connected to headers by means of metal joist hangers or ledger strip.
(7) (a) Maximum clear spans for wood floor and ceiling joists shall be in accordance with the joist span schedule in § 150.200.
(b) In applying regulations of the joist span schedule, § 150.200, finished ceilings shall be considered a ceiling covered with drywall, plaster or other approved material. An attic shall be deemed accessible when served by means other than a scuttle hole.
(8) (a) Approved draftstopping shall be provided to close concealed draft openings and shall form an effective fire and smoke barrier between rooms and stories.
(b) Draftstopping shall be provided in pipe chases, holes for pipes, soffits, dropped or lowered ceilings, concealed roof spaces and other locations which could induce draft or permit passage of smoke. Concealed roof spaces shall be draftstopped at maximum intervals of 20 feet horizontally.
(9) Wall sheathing of approved wood, plywood, fiber board or gypsum shall be installed on exterior walls.
(a) Wood sheathing shall be one-inch nominal thickness.
(b) Plywood sheathing shall be a minimum of one-half inch type C.D. exterior grade.
(c) Fiber board sheathing shall be not less than one-half-inch thick moisture resistant material.
(d) Gypsum sheathing shall be a minimum of one-half inch thick.
(10) (a) 1. Roof and floor sheathing shall be of one inch nominal thickness solid wood or a minimum of one-half inch type C.D. exterior grade plywood when applied to framing members which are 16 inches on center or less.
2. Boards of one inch nominal thickness or minimum five-eighths inch type C.D. exterior plywood shall be used when applied to framing members which are more than 16 inches on center, but not more than 24 inches on center.
(b) 1. When single layer floor sheathing is used as a base for carpeting, the framing members shall not exceed 24 inches on center.
2. The sheathing shall be not less than three-fourths inch tongue and groove exterior grade plywood glued and nailed to the framing members.
3. Non-carpeted areas shall be covered with a minimum one-fourth inch underlayment material.
(11) Single bottom plates and double top plates shall be provided at all bearing walls. Any splice or break in the top or bottom plate shall occur at a stud.
(Prior Code, § 9-122) (Ord. 94-11B, passed 4-21-1994; Ord. 94-15, passed 4-21-1994)