SECTION 550: TREATED TIMBER
550.1 Description
This Work consists of construc ting timber Structures and the ti mber portions of composite Structures.
550.2 Materials
550.2.1 Sawn Lumber and Timber
The Contractor shall provide sawn lumber and timber in accordan ce with AASHTO M 168, and the National Forest Products Association’s National Design Specification for Wood Construction. The Contractor shall meet grading rules and design values in ac cordance with Supplement to the National Design S pecifications for Wood Construction .
550.2.2 Preservatives and Treatment Methods
The Contractor shall treat timber with preservatives in accorda nce with AASHTO M 133 and AWPA U1, Commodity Section A: Sawn Products; or use pentach lorophenol, Type C preservative treatment in accordance with AWPA P8 and P9.
550.2.3 Fasteners
The Contractor shall provide bolts, nuts, and washers in accord ance with ASTM A 307. The Contractor shall provide bolts that have standard, square o r hex heads, and coarse threads with Class 2 tolerances in accordance with ANSI’s Standard Specifications for Bolted Connections . The Contractor shall provide washers that bear on timber surfac es in accordance with Table 550.2.3:1, “Washer Dimensions.” Table 550.2.3:1 Washer Dimensions Bolt diameter Hole diameter Washer diameter Washer thickness 1/2 9/16 1 3/8 3/32 3/4 13/16 2 5/32 7/8 15/16 2 1/4 11/64 The Contractor shall provide shear plates and split ring connec tors in accordance with the Contract. The Department will not accept connector plates with punched-through spikes or nailer plates. The Contractor shall provide shear plates, split ring connector s, and accompanying washers made of pressed steel or malleable iron in accordance w ith AITC’s Timber Construction Manual . The Contractor shall use nails cut from round wire of standard form. The Contractor shall use cut or wire spikes. The Contractor shall use galvanized metal fasteners in accordan ce with AASHTO M 232. Section 550: Treated Timber Page 562 The Contractor shall tap galvani zed nuts oversize after galvani zing in accordance with ASTM A325 and ASTM A 563. The Contractor shall provide steel plates in accordance with AS TM A36; galvanize in accordance with AASHTO M 232 or M 111.
550.2.4 Timber and Lumber Certification
The Contractor shall provide timber and lumber certified by an American Lumber Standards Committee certified agency.
550.2.5 Preservative Treatment Certification
The Contractor shall provide a certificate from the treatment f acility or an independent inspection agency containing the following: 1. Preservative type and composition; 2. Quantity retained in pounds per cubic foot (ASSAY Method); 3. Confirmation that specification requirements were met; and 4. Copies of inspection reports.
550.3 Construction Requirements
550.3.1 Working Drawings and Written Procedures
The Contractor shall submit three (3) sets of Working Drawings and erection drawings to the Department. The Department will return one (1) set with no tations within 14 Days. The Contractor shall provide up to eight (8) sets, as required, of corrected Working Drawings for final approval. The Contractor shall allow seven ( 7 ) D a y s f o r r e v i e w o f r e - submitted Working Drawings. The Contractor shall not begin fabrication before receiving wri tten approval. The Contractor shall ensure the Working Drawings contain a mini mum of the following: 1. Complete details of the Stru cture timber components, includi ng the following: 1.1. Dimensions; 1.2. Details; 1.3. Cut, bevel, and notch locations; and 1.4. Hole sizes. 2. Hardware details and parts lis ts for items such as connector plates, shear plates, split-ring connectors, lag screws, bolts, nuts and washers, inc luding protective coating requirements; 3. Timber grade and species; 4. Preservative treatment (type, composition and percent retent ion); 5. An erection diagram showing pi ece marks, locations, orientat ions and attachment methods for Structure components or pieces; and 6. Special instructions required regarding Structure fabricatio n or erection.
550.3.2 Fabrication
Section 550: Treated Timber Page 563 The Contractor shall cut and frame lumber and timber so that th e joints have an even bearing over the entire contact surfaces. The Contractor shall tag prefabricated members with erection ma rks for identification and reference them in the erection drawings. Unless otherwise specified, the Contractor shall fabricate as f ar ahead of treatment as possible.
550.3.2 1 Bolt Holes
Unless otherwise specified in the Contract, the Contractor shal l bore holes perpendicular to the faces of the members they penetrate. The Contractor shall bore connection holes for one (1) or two ( 2) bolts at the same diameter as the finished bolt, e xcept bolt holes which are part of a shear plate or split-ring assembly. The Contractor shall bore holes 1/16 inch larger than the bolt diameter for bolted connections using more than two (2) bolts, and for bolt holes w hich are part of a shear plate or split-ring assembly. The Contractor shall drill holes in connector plates 1/16 inch larger than the bolt diameter.
550.3.2 2 Holes for Lag Screws
For lag screws, the Contractor shall bore holes with a bit no l arger than the minor diameter of the lag screw thread. To prevent splitting or stripping the threads, the Contractor s hall bore shank holes in the side of the joint containing the thread to the same diameter an d to the same depth as the shank. The Contractor shall ensure that holes for the shank in connected parts (wood or metal) are from 1/32 inch to 1/16 inch greater than the diamete r of the shank. The Contractor shall make the hole depths approximately one (1) inch less than the length under the head.
550.3.2 3 Recesses and Countersinking
The Contractor shall countersink when the Contract requires a s mooth or flush surface. The Contractor shall treat recesses in treated timber, formed f or shear plates, split-ring connectors or countersinking, i n accordance with Section 550.3. 3, “Preservative Treatment.”
550.3.2 4 Stringers
The Contractor shall size stringers at bearings and place so th at knots near edges are in the top portions of the stringers. The Contractor may construct outside stringers butt joints with the ends dapped or cut on a taper. Unless otherwise specified in the Contract, the Contr actor shall overlap interior stringers at each end to take the bearing over the full floor b eam or cap width.
550.3.2 5 Cross Bridging
The Contractor shall toenail wood cross bridging between string ers with at least two (2) Section 550: Treated Timber Page 564 nails in each end. The Contractor shall ensure the cross bridg ing members have full bearing at each end against the stringer sides. The Contractor shall u se metal cross bridging members in accordance with the Contract or as approved by the D epartment.
550.3.2 6 Trusses
The Contractor shall ensure the following: 1. Completed trusses show no line irregularities; 2. Chords are straight and true from end to end in horizontal p rojection; and 3. Chords show a smooth curve through panel points in vertical projection. The Department will reject pieces with uneven or rough cuts at the bearing points.
550.3.2 7 Bolts and Washers
The Contractor shall install washers under bolt heads and nuts unless using a steel plate or strap in conjunction with shea r plates. If necessary, the C ontractor shall use washers to extend the bolt length to prev ent metal connection plates from bearing on the threaded portion of the bolt.
550.3.2 8 Nailing
Unless otherwise specified, the Contractor shall drive nails an d spikes perpendicular to the surface of the timber with just enough force to set the hea ds flush with the surface of the wood. The Department may reject surfaces with deep hammer mark s, considered evidence of poor workmanship.
550.3.3 Preservative Treatment
The Contractor shall apply preser vative treatment in accordance with AWPA M4.
550.3.3 1 Marking
The Contractor shall ensure that each piece of treated timber h as a legible brand, mark, or tag indicating the treatment facility name and the specifica tion symbol or specification requirements identifying the treatment used. The Contractor sh all place the brands or marks so that they are not visible after the Structure is erected.
550.3.3 2 Inspection at the Treatment Plant
The Contractor is responsible fo r inspection of Materials and p reservative treatment. The Contractor shall ensure that inspections are conducted in a ccordance with AASHTO M 133 and AWPA Standards. Third Party Inspection agenc ies must be ALSC approved. The Department may conduct surve illance inspections at any time .
550.3.3 3 Inspection at the Job Site
The Department may retest the Materials after delivery to the P roject. The Department will accept timber within five percent (5%) of s pecified moisture content and preservative retention.
550.3.4 Handling
The Contractor shall handle treated timber with web slings. Th e Contractor shall not use devices that mar wood surfaces, s uch as cant hooks, peaveys, an d pikes. If using metal bands to bundle members, the Contractor shall pr ovide comer protectors to prevent damage to the treated timber.
550.3.5 Storage of Material
The Contractor shall store lumber and timber on the Project in orderly stacks. The Contractor shall stack Material on supports at least 12 inches above the ground surface. The Contractor shall keep the ground in the vicinity of the timber cleared of weeds and rubbish. The Contractor shall not allow water to collect under or near t he stored timber. If required by the Project Manager, the Contractor shall provid e protection from the weather with a covering.
550.3.6 Erection
The Contractor shall treat cuts, abrasions, and recesses that o ccur after treatment with two (2) liberal applications of a compatible preservative in ac cordance with AWPA M4. The Contractor shall treat holes bored after treatment by filli ng the holes with the preservative used for field treatment. The Contractor shall us e preservative treated plugs to plug holes not permanently filled with bolts or screws. The Contractor shall tighten bolts securely, but not enough to crush the wood beneath the plates or washers. The Department will reject members that will not assemble after application of reasonable amounts of force.
550.4 Method of Measurement
550.4.1 Treated Timber
The Department will use standard nom inal dimensions and actual member lengths, in accordance with the Contract o r approved modifications, to meas ure treated timber.
550.4.2 Metal Components
The Department will pay for metal components, exclusive of nail s and spikes, in accordance with Section 541, “Steel Structures.”
550.5 Basis of Payment
Pay Item Pay Unit Treated Timber Thousand Board Feet
550.5.1 Work Included in Payment
The following Work and items will be considered as included in the payment for treated timber and will not be measured or paid for separately: 1. Inspection costs; Section 550: Treated Timber Page 566 2. Coating of timber Structures; and 3. Nails and spikes. Section 560: Elastomeric Bearing Pads Page 567