Quality of structural timber-product specification system required by end-users

Abstract

Interviews conducted with the end-users of timber products revealed that their knowledge of timber is very poor. However, building contractors are not satisfied with the quality of timber, primarily as a result of its excessive warp. Their requirements are not passed on to the producers in the forest and sawmill industry. The quality of a timber product should be described in a specification of requirements for each individual product. In this paper, a systematic analysis of the end user's expectations is presented and is illustrated using a product specification for wall studs. The proposed acceptance levels are based on interviews with contractors and derived from the requirements set for the wall. The current grading rules are more generous than our proposal. Field tests by carpenters showed that our proposal limits appear to be reasonable. A study of commercially-available studs showed that it should be possible both technically and economically to produce studs which fulfil our requirements. If timber is to hold its own as a building material, the forest and sawmill industry will have to produce products which match the end user's requirements.