4. Forest Service Supplemental Specifications.pdf

Section 716

Section 716. — MATERIAL FOR TIMBER STRUCTURES

716.01 Untreated Structural Timber and Lumber. Conform to AASHTO M 168. Furnish an inspection certification from an agency accredited by the American Lumber Standards Committee for the species and grade. Mark pieces with the inspection service, grade designation, species, and inspector identity.

Season and dry structural timber and lumber before fabrication. Do not use material that is twisted, curved, or otherwise distorted.

Do not use boxed-heart pieces of Douglas fir or redwood in outside stringers, floor beams, caps, posts, sills, or rail posts. Boxed-heart pieces are defined as timber so sawed that, at any point in the length of a sawed piece, the pith lies inside the four faces.

716.02 Hardware. Machine bolts, drift bolts and dowels may be medium steel. Fabricate washers from gray iron or malleable iron castings unless structural washers are specified.

Use a standard commercial type of cut or round nail. Use cut, round, or boat spikes as specified.

Galvanize hardware according to AASHTO M 232.

Use ring or shear-plate timber connectors conforming to Division II, Article 16.2.6, Timber Connectors of

AASHTO LRFD Bridge Construction Specifications for Highway Bridges.

716.03 Treated Structural Timber and Lumber. Furnish wood according to Subsection 716.01. Make dimensional cuts, holes, and incise wood before pressure treatment. Treat the wood according to AWPA

Standard U1, Use Specification for Treated Wood and T1 Processing and Treatment Standard. Use the type of treatment shown in the plans.

Treat timber members according to the requirements of the current edition of Western Wood Preservers

Institute’s Best Management Practices for the Use of Treated Wood in Aquatic Environments.

Treated timber members must have a quality mark approved by the American Lumber Standards

Committee for individual pieces or sealed pallets assuring that treatment conforms to the appropriate

AWPA standards.

716.04 Structural Glued Laminated Timber. Furnish structural glued laminated timber according to

American Institute of Timber Construction’s AITC 117, Design Specifications for Structural Glued

Laminated Timber of Softwood Species. Fabricate according to the combination and grade as indicated in the contract. Fabricate structural glued laminated members according to ANSI/AITC A190.1, American

National Standard for Structural Glued Laminated Timber.

Manufacture members as industrial appearance grade for wet use conditions. Use adhesives conforming to the requirements of ASTM D2559 and AITC 405, Standard for Wood Products - Structural Glued

Laminated Timber. Use only single- or multiple-piece laminations with bonded edge joints.

Straight or slightly cambered members which are to be loaded perpendicular to the wide face of the laminates must be stamped "top" on the top at both ends of the beam.