Section 2409. Timber Structures.
This section shall apply to construction of structures composed wholly of timber or of timber combined with structural steel or concrete. The provisions of Sections 2401, 2402, 2403, 2404, 2405, 2408, and 2501 shall apply to various phases of the construction. Timber portions of the structure shall be built to conform to the contract documents and requirements of this section.
All materials used in timber construction shall meet requirements of Division 41 for the respective material as follows:
A. Timber and Lumber.
Untreated structural parts to be painted shall be furnished surfaced four sides. All stringers shall be surfaced two edges, top and bottom. All other sawed timber shall be furnished rough unless otherwise specified.
1. Untreated Structural and Common Timber.
Section 4162 shall apply.
2. Treated Timber.
Section 4163 shall apply.
Section 4165 shall apply.
Section 4152 shall apply to steel rods for tension members or tie rods for wingwalls, all plates and structural shapes, and all drift pins and dowels. Section 4151 shall apply to concrete reinforcement.
C. Hardware and Nails.
Article 4153.07 shall apply.
Paint shall be as specified in the contract documents.
E. Wood Preservative.
Article 4160.01 shall apply.
F. Waterproofing Materials.
Waterproofing materials shall be as specified in the contract documents.
G. Timber Connectors.
Connectors for resisting shearing stresses between tension members and for spreading the stress over the entire member shall be of a design approved by the Engineer. They shall be made of metal and shall be of sufficiently rugged type to withstand handling and installing without damage.
When the contract documents specify tie rods to be coated with waterproofing, the rods shall first be cleaned in accordance with Article 2508.01, A and painted in accordance with the manufacturer's recommendations. For fastening and bracing other members to piles, the Contractor shall furnish bolts in a variety of lengths which will conform to the diameter, shape, and position of the piles so that extra washers or shims will not be required to take up the extra length of bolt.
STORAGE OF MATERIALS.
Lumber and timber, when delivered to the site of the work, shall be stored in neat piles. The ground underneath and in the vicinity of material piles shall be cleared of weeds and rubbish. Piles of lumber shall be arranged to shed water and prevent warping and, if stored over a long period, shall be further protected by suitable covering.
Untreated lumber shall be open stacked on suitable skids at least 12 inches (0.3 m) above ground and above possible high water.
Treated timber and treated piling shall be close stacked and piled. When stored for long periods, the tops of stacks and ends of pieces shall be covered to protect the material from the direct rays of the sun.
Miscellaneous material and hardware shall be stored so as to prevent loss or damage.
HOLES FOR BOLTS, DOWELS, RODS, AND SCREWS.
Holes for drift bolts and dowels shall be bored 1/16 inch (2 mm) smaller than the nominal diameter of the bolt or dowel used. Holes for lag screws shall be bored with a bit not larger than the body of the screw at the base of the thread.
Holes for rods and bolts, other than drifts and dowels, shall be bored to diameters as follows:
Holes bored in timber before treatment shall be 1/8 inch (3 mm) larger than the nominal diameter of the bolt or rod used.
Holes bored in timber not to be treated or bored in timber after treatment shall be the same as the nominal diameter of the bolt or rod used.
Where the heads of bolts or lag screws would interfere with traffic or with other structural parts, they shall be countersunk.
TREATMENT OF TREATED PILE HEADS.
All surfaces of treated pile heads cut after treatment shall be treated with material specified in Section 4161.
QUALITY OF WORK.
All framing shall be true and exact. Nails and spikes shall be driven with just sufficient force to set the heads flush with the wood surface. Deep hammer marks in wood surfaces will be considered as evidence of poor work quality. Washers shall be used under all bolt heads and nuts which would otherwise be in contact with wood.
Treated timbers shall be carefully handled without sudden dropping, breaking of outer fibers, bruising, or penetrating the treated surface with tools, such as cant hooks, peaveys, timber tongs, or pike poles.
All lumber and timber shall be accurately cut and framed to a close fit in such manner that joints will have even bearing over the entire contact surfaces.
All holes in stringers, rails, posts, post blocks, and scupper blocks shall be bored before the timber is treated. All cutting, framing, and boring of treated timbers shall be done before treatment, whenever practicable. Whenever boring or framing must be performed after preservative treatment, newly exposed surfaces shall be treated as follows: All daps, cuts, chamfers, and all abrasions, after having been carefully trimmed, shall be given two coats of copper naphthanate. All countersunk holes shall be given two coats of copper naphthanate before the bolt is placed.
Grooves and daps for timber connectors shall make a tight fit with that part which is embedded in wood. For types of connectors which permit, adjacent wood surfaces shall be drawn into tight contact with each other. For types which will not permit this surface contact, the opening left by the connector shall be filled with plastic cement troweled upon the surface before the joint is finally assembled. After assembly, excess plastic cement which is squeezed out shall be struck off flush, and any opening in the joint pointed full.
Pile bents shall be driven as accurately as possible in the correct location and to vertical or batter lines indicated on the plans. In case a pile is driven out of line, it shall be straightened without damage before it is cut off or braced. Piles damaged in driving or straightening or piles driven below grade shall be removed and replaced if directed by the Engineer. Shimming of tops of piles shall not be permitted.
Piles for any one bent shall be carefully selected as to size to avoid undue bending or distortion of sway bracing.
Cutoffs shall be accurately made to insure satisfactory bearing between the cap and all piles of a bent. Edges of piles outside the cap shall be trimmed to a slope approximately 45 degrees with horizontal.
Framed bents shall be constructed as shown in the contract documents. In general, they will be supported by piles cut off approximately 3 feet (1 m) above ground level. Earth shall be removed from contact with sills to allow free circulation of air. Sills shall be fastened to the piles, and posts shall be fastened to sills, by dowels not smaller than 3/4 inch (19 mm) in diameter, projecting into both pile and sill not less than 6 inches (150 mm).
Timber caps shall be placed to secure an even, uniform bearing on the top of supporting piles or posts. They shall be fastened to piles by drift pins not less than 3/4 inch (19 mm) in diameter, extending at least 9 inches (225 mm) into the piles.
Drift pins shall be placed approximately in the center of the pile or cap. When steel channel caps are used, the tops of all piles shall be accurately shaped to provide snug fit in the caps.
The ends of bracing shall be bolted through the pile, post, or cap with bolts not less than 5/8 inch (16 mm) in diameter. Intermediate intersections shall be fastened with bolts and spikes as shown in the contract documents. In all cases, spikes shall be used in addition to bolts. Notching the piles or shimming under the bracing shall be avoided whenever possible.
Stringers shall be sized at bearings and shall be placed in position so that knots near the edges shall be in top portions of the stringers. Outside stringers may have butt joints, but interior stringers shall be lapped to take full bearing on caps. Stringers shall be fastened to caps as shown in the contract documents.
Bridging shall be of the size and type shown in the contract documents. With untreated stringers and floors, bridging shall be placed so that an air space of at least 1 inch (25 mm) shall be left beneath the floor. With treated stringers and floors, bridging shall be placed flush with the top of the stringers.
Wood surfaces of the structure which are to be painted will be designated in the contract documents. All surfaces to be painted shall be cleaned in accordance with Article 2508.01, A, 1 and 2, painted with a paint system specified in the contract documents, and painted in accordance with the paint manufacturer's recommendations.
All metal work, except galvanized hardware, shall be painted as provided in Article 2408.30.
Floors for timber structures shall be of the type specified in the contract documents. Floors shall be constructed in accordance with the provisions of Sections 2410, 2411, and 2412.
All concrete required in connection with timber structures shall meet requirements of Section 2403.
METHOD OF MEASUREMENT.
The quantity of timber and lumber will be computed by the Engineer in thousands of board feet (cubic meters) from the nominal width and thickness, and the length measured to the nearest foot (0.1 m) for the material used in the finished work.
The weight (mass) of structural steel measured shall include net weights (the mass) of rolled shapes or plates, of rods used as tension members, and of all bolts and rivets used to fasten steel parts together.
The weight (mass) of drift bolts, dowels, washers, bolts, and other hardware used to fasten wood parts together or to steel members will not be included in the weight (mass) of structural steel, but such items shall be included in the weight (mass) of miscellaneous hardware and shall be so computed by the Engineer.
Spikes and nails will not be measured separately for payment but shall be considered incidental to timber construction.
BASIS OF PAYMENT.
For the quantities involved in timber structures, the Contractor will be paid in accordance with the following: Excavation for Structures, Section 2402; Structural Concrete, Section 2403; Steel Reinforcement, Section 2404; Structural Steel, Section 2408.
For the quantity of miscellaneous hardware, the Contractor will be paid the contract unit price per pound (kilogram). For the quantity of treated and untreated timber and lumber, the Contractor will be paid the contract unit price per thousand board feet (cubic meter), which shall include the cost of spikes and nails. This payment shall include furnishing all materials, equipment, and labor, and for performance of all incidental work necessary to complete the structure in conformance with the contract documents.