**Construction Specification 83---Timber Fabrication and Installation**

**1. Scope**

The work shall consist of the construction of timber structures and
timber parts of composite structures.

**2. Material**

Structural timber and lumber shall conform to the requirements of
Material Specification 584. Treated timber and lumber shall be
impregnated with the specified type and quantity of preservative and in
the manner specified in Material Specification 585.

Hardware, except cast iron, shall be galvanized as specified for iron
and steel hardware in Material Specification 582. Unless otherwise
specified, structural steel shapes, plates, and rods shall not be
galvanized. Nuts, driftbolts, dowels, and screws shall be either wrought
iron or steel.

Steel bolts shall conform to the requirements of ASTM A 307. When
galvanized or zinc-coated bolts are specified, the zinc coating shall
conform to the requirements of Material Specification 582.

Washers shall be ogee gray iron castings or malleable iron castings
unless washers cut from medium steel or wrought iron plate are specified
on the drawings or in section 7 of this specification. Cast washers
shall have a thickness equal to the diameter of the bolt and a diameter
equal to four times the thickness. The thickness for plate washers shall
be equal to half the diameter of the bolt, and the sides of the square
shall be equal to four times the diameter of the bolt. Holes in washers
shall have a maximum diameter of 1/8 inch larger than the diameter of
the bolt. Split ring connectors, tooth ring connectors, and pressed
steel shear plate connectors shall be manufactured from hot-rolled, low
carbon steel conforming to the requirements of ASTM A 711, Grade 1015.
Malleable iron shear plate connectors and spike grid connectors shall be
manufactured in conformance with the requirements of ASTM A 47, Grade
No. 35018. All connectors shall be of approved design and the type and
size specified.

Structural shapes, rods, and plates shall be structural steel conforming
to the requirements of Material Specification 581. No welds are
permitted in truss rods or other main members of trusses or girders.

**3. Workmanship**

All framing shall be true and exact. Timber and lumber shall be
accurately cut and assembled to a close fit and shall have even bearing
over the entire contact surface. No open or shimmed joints will be
accepted. Nails and spikes shall be driven with just sufficient force to
set the heads flush with the surface of the wood. Deep hammer marks in
wood surfaces shall be considered evidence of poor workmanship and may
be sufficient cause for rejection of the work.

Holes for round driftpins and dowels shall be bored with a bit 1/16 inch
smaller in diameter than that of the driftpin or dowel to be installed.
The diameter of holes for square driftpins or dowels shall be equal to
one side of the driftpin or dowel. Holes for lag screws shall be bored
with a bit not larger than the body of the screw at the base of the
thread.

Washers shall be used in contact with all bolt heads and nuts that would
otherwise be in contact with wood. Cast iron washers shall be used when
the bolt will be in contact with earth. All nuts shall be checked or
burred effectively with a pointed tool after finally tightened.

Unless otherwise specified, surfacing, cutting, and boring of timber and
lumber shall be completed before treatment. If field cutting or field
repair of treated timber and lumber is approved, all cuts and abrasions
shall be carefully trimmed and coated with two paint-on or swab-applied
applications of a wood preservative that is not less than 5 percent (by
weight) pentachlorophenol. A copper metal solution of 2 percent (by
weight) copper naphthenate may be used as a replacement for
pentachlorophenol, which is a controlled substance. After timber
assembly, any unfilled holes shall be plugged with tightly fitting
wooden plugs that have been treated with preservative as specified.

**4. Handling and storing material**

All timber and lumber stored at the site of the work shall be neatly
stacked on supports a minimum of 12 inches above the ground surface and
protected from the weather by suitable covering(s). Untreated material
shall be staked and stripped to permit free circulation of air between
the tiers and courses. Treated timber may be close-staked. The ground
surface for the stockpile of timber and lumber shall be free of weeds
and rubbish. The use of cant hooks, peavies, or other pointed tools
except end hooks is not permitted in the handling of structural timber
and/or lumber. Treated timber shall be handled with rope slings or by
other methods that prevent the breaking or bruising of outer fibers or
penetration of the surface in any manner.

**5. Painting**

Except as otherwise specified, surfaces designated for painting shall be
prepared and painted in accordance with Construction Specification 84.

**6. Measurement and payment**

***Method 1---***The unit of measurement of lumber and timber is the
number of thousand feet board measure (MBM) of each type, size, species,
and grade of lumber and timber installed in the completed structure. The
quantity of each type, size, species, and grade is computed from the
nominal dimensions and actual lengths of the pieces in the completed
structure and does not include waste timber used for erection purposes
(such as falsework or temporary sheeting and bracing) or any part of any
pile or other round timber. The total quantity of lumber and timber in
each type, size, species, and grade is computed to the nearest 0.01 MBM.

The unit of measurement of plywood is the number of square feet of each
type, species, grade, and thickness installed in the completed
structure.

Payment for each type, size, species, and grade of lumber and timber is
made at the contract unit price for that type, size, species, and grade.
Payment for each type, species, grade, and thickness of plywood is made
at the contract unit price for that type, species, grade, and thickness.
Such payment is considered full compensation for completion of the work.

***Method 2---***No measurement of material quantities is made. Payment
for each structure, complete in place, is made at the contract lump sum
price for that structure. Such payment is considered full compensation
for completion of the work.

***Method 3---***For items of work for which specific unit prices are
established in the contract, measurement and payment for each structure
unit except those for which a linear foot payment is established is
counted and payment made at the contract unit price. Items for which a
linear foot payment is established are measured to the nearest linear
foot, and payment is made at the contract unit prices as appropriate.
Such payment is considered full compensation for completion of the work.

***All methods---***The following provisions apply to all methods of
measurement and payment. Compensation for any item of work described in
the contract, but not listed in the bid schedule, is included in the
payment for the item of work to which it is made subsidiary. Such items
and the items to which they are made subsidiary are identified in
section 7 of this specification.

**7. Items of work and construction details**