ITEM 410 – TREATED AND UNTREATED TIMBER

410.1 Description

This Item shall consist of structural timber of the specie and size called for on the Plans, either treated or untreated as called for in the Proposal. It shall include the furnishing of the timber, the framing, erecting, furnishing of hardware and the furnishing of paint and paintings if paint is called for on the Plans or in the Special Provisions.

410.2 Material Requirements

410.2.1 Timber

Timber shall be the specie specified on the Plans. Unless otherwise noted on the Plans or in the Special Provisions, only the best grade shall be used. It shall be free from loose knots, splits, worm holes decay, warp, ring separation, or any defect which will impair its strength or render it unfit for its intended use. Any specie specified on the Plans may be used for untreated timber and if that specie is not available, a specie of equivalent strength and durability may be used if authorized by the Engineer. If the timber is to be treated, only those species shall be used which are known to possess properties which make them favorable to treatment.

410.2.2 Paint

When painting of timber is required, the paint shall conform to the requirements of Item 411, Paint.

410.2.3 Hardware

Hardware shall conform to the requirements of Item 402, Timber Structures.

410.2.4 Preservatives

The preservatives shall be creosote oil or creosote petroleum oil blend as called for on the Plans or by the Special Provisions, and shall conform to the Standard Specifications for Pressure Treatment of Timber Products, ASTM D 1760.

When timber is intended for marine use, the creosote petroleum oil blend shall not be used.

410.3 Construction Requirements

410.3.1 Timber Treatment

Treatment shall consist of the forcing of either creosote oil or a creosote petroleum oil mixture into the outer fibers of the timber by a heat and pressure process. The process shall be in accordance with AASHTO M 133, preservatives and pressure treatment process for timber, but with such changes in temperatures, pressures, duration of treatment and other factors affecting the final treatment that experience has shown to be necessary in the treatment of structural timbers sawn from woods native to the Philippines. The treatment shall be so regulated that the curing process will not induce excessive checking.

The minimum penetration of the preservative into the surface of the timber shall be 20 mm. The minimum retention of the preservative per cubic meter of timber shall be as follows:

For general use, 192 kg by empty cell process

For marine use, 320 kg by full cell process

The Engineer shall be notified at least 10 days in advance of the date that the treating process will be performed in order that the untreated timber, the treatment process, and the finished treatment timber may all be inspected. The Engineer shall inspect the timber prior to treatment to determine conformance with those Specifications and suitability of conditions for treatment. He shall be permitted free access to the plant in order that temperatures, pressures and quantities and type of treatment materials used may be observed. Samples of the creosote or creosote petroleum oil mixture shall be furnished as required for tests.

After completion of the treatment, the timber shall be checked to determine penetration of treatment, amount of checking quantity of free preservative remaining on the timber and will check any other visual evidence that the treatment has been performed in a satisfactory manner. The penetration of treatment shall be determined by boring a sufficient number of well-distributed holes to determine the average penetration. All such holes shall be plugged with plugs approximately 1.6 mm larger in diameter that the bit used in boring the holes.

If the penetration of preservative is less than the required amount, the entire charge, or such parts thereof as are determined by the Inspector to be unsatisfactory, may be retreated. If after retreatment the penetration is still insufficient, the treated pieces shall be rejected.

Any excessive checking caused by the treating process shall be cause for rejection of the pieces in which the excessive checking occurs.

The treating plant shall be equipped with adequate thermometers and pressure gauges so that the process can be accurately controlled and a continuous record made of all stages of the treating process. If required by the Engineer, records shall be furnished showing the duration, maximum and minimum temperatures and pressures used during all stages of the process.

410.4 Method of Measurement

The quantity to be paid for shall be the number of cubic meter of timber complete in place and accepted. Measurement of timber shall be computed from the nominal dimension of the timber even though the actual dimensions may be scant. The measurement of timber shall include only such timber as a part of the completed and accepted work and will not include any timber required for a falsework, bracing or other timber required in the erection.

410.4 Basis of Payment

The quantities, determined as provided in Section 410.4, Method of Measurement, shall be paid for at the contract unit price per cubic meter for Timber or Untreated Timber as called for in the Proposal, which price and payment shall constitute full compensate for furnishing all timber, for preservative treating when required, and for the delivery, framing, erecting, painting if required, and for the furnishing of all labor, hardware, tools, equipment and incidentals necessary to complete the Item.

Payment will be made under:

Pay Item Number	Description	Unit of Measurement
410 (1) 410 (2)	Timber Treated Timber	Cubic Meter Cubic Meter