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Building Design and Construction Handbook - Merritt - Ventech!

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WOOD CONSTRUCTION 10.85<br />

sometimes used to meet a specific flame-spread rating for interior finish, or as an<br />

alternative to code requirements for noncombustible construction.<br />

10.29 TIMBER FABRICATION AND ERECTION<br />

During fabrication <strong>and</strong> erection processes for wood construction, wood products<br />

should be h<strong>and</strong>led <strong>and</strong> covered to prevent marring of the surfaces <strong>and</strong> moisture<br />

absorption. Overstressing of members <strong>and</strong> joints during h<strong>and</strong>ling <strong>and</strong> erection<br />

should be avoided. Competent inspectors should check materials <strong>and</strong> workmanship.<br />

10.29.1 Fabrication of Structural Timber<br />

Fabrication consists of boring, cutting, sawing, trimming, dapping, routing, planing,<br />

<strong>and</strong> otherwise shaping, framing, <strong>and</strong> finishing wood units, sawn or laminated, including<br />

panels, to fit them for particular places in a final structure. Whether fabrication<br />

is performed in shop or field, the product must exhibit a high quality of<br />

workmanship.<br />

Jigs, patterns, templates, stops, or other suitable means should be used for all<br />

complicated <strong>and</strong> multiple assemblies to ensure accuracy, uniformity, <strong>and</strong> control of<br />

all dimensions. All tolerances in cutting, drilling, <strong>and</strong> framing must comply with<br />

good practice <strong>and</strong> applicable specifications <strong>and</strong> controls. At the time of fabrication,<br />

tolerances must not exceed those listed below, unless they are not critical <strong>and</strong> not<br />

required for proper performance. Specific jobs, however, may require closer tolerances.<br />

Location of Fastenings. Spacing <strong>and</strong> location of all fastenings within a joint<br />

should be in accordance with the shop drawings <strong>and</strong> specifications, with a maximum<br />

permissible tolerance of � 1 ⁄16 in. The fabrication of members assembled at<br />

any joint should be such that the fastenings are properly fitted.<br />

Bolt-Hole Sizes. Bolt holes in all fabricated structural timber, when loaded as a<br />

structural joint, should be 1 ⁄16 in larger in diameter than bolt diameter for 1 ⁄2-in <strong>and</strong><br />

larger-diameter bolts, <strong>and</strong> 1 ⁄32 in larger for smaller-diameter bolts. Larger clearances<br />

may be required for other bolts, such as anchor bolts <strong>and</strong> tension rods.<br />

Holes <strong>and</strong> Grooves. Holes for stress-carrying bolts, connector grooves, <strong>and</strong> connector<br />

daps must be smooth <strong>and</strong> true within 1 ⁄16 in per 12 in of depth. The width<br />

of a split-ring connector groove should be within �0.02 in of <strong>and</strong> not less than the<br />

thickness of the corresponding cross section of the ring. The shape of ring grooves<br />

must conform generally to the cross-sectional shape of the ring. Departure from<br />

these requirements may be allowed when supported by test data. Drills <strong>and</strong> other<br />

cutting tools should be set to conform to the size, shape, <strong>and</strong> depth of holes,<br />

grooves, daps, etc., specified in the ‘‘National <strong>Design</strong> Specification for Wood <strong>Construction</strong>,’’<br />

American Forest & Paper Association.<br />

Lengths. Members should be cut within � 1 ⁄16 in of the indicated dimension when<br />

they are up to 20 ft long, <strong>and</strong> � 1 ⁄16 in per 20 ft of specified length when they are<br />

over 20 ft long. Where length dimensions are not specified or critical, these tolerances<br />

may be waived.

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