Approved Products List – Bridges & Structures

Specifications for Timber

All timber must meet the requirements of CAN/CSA O141-05 Softwood Lumber (latest edition) and adhere to MI’s Bridge Construction Specifications for Timber.

Timber shall be No. 1 structural grade or better coastal douglas fir as per WCLIB (West Coast Lumber Inspection Bureau) and WWPA (Western Wood Products Association), S4S (surfaced on four sides) and shall be pressure treated with ACZA preservative to a retention of 4.0 kg/m3 in accordance with CAN/CSA O80 Series-08 Consolidated Wood Preservation (latest edition).

If lumber is not being treated, it must be “dry”, with a moisture content below 19%, to prevent rot and decay.

Timber decking shall be in accordance with CAN/CSA O141-05 Softwood Lumber (latest edition) and “Best Management Practices for the use of Treated Wood in Aquatic and Wetland Environments”, published by the Western Wood Preserver’s Institute.

Timber must be coastal douglas fir, as douglas fir from the interior is much more difficult to treat.

 

Pine

All timber (pine) shall be pressure treated with preservative in accordance with the requirements of CAN/CSA O80 Series-08 Consolidated Wood Preservation (latest edition).

All wood will be graded in accordance with NLGA standard grading rules for Canadian lumber.

All timber shall be Pine No. 2 grade or better.

Unless otherwise noted, the actual size of sawn lumber after surfacing shall be in accordance with Canadian standards.

All provisions of American Wood Protection Association (AWPA) M4 Standard for the Care of Preservative-Treated Wood Products (latest edition) must be undertaken.

 

Railposts

All timber to be used in railposts shall be No. 1 Structural Grade supplied in accordance with 1987 NLGA or equivalent WCLIB No. 16 Grading Rules, and have a minimum allowable bending stress of 8.3 MPa.

All timber shall be treated in accordance with the requirements of CAN/CSA O80 Series-08 Consolidated Wood Preservation (latest edition).