Cutting of Round Timber with Heart Rot to Structural Lumber

Abstract

Softwood lumber is widely used for the manufacture of load-bearing structures. However, the quality of round timber for lumber manufacturing has been deteriorating recently. The average diameter of round timber entering sawmills is constantly decreasing, and heart rot is common in large-diameter round timber. This is due to the fact that more and more conifers in the forest are being affected by heart rot. The rot infestation is related to the deterioration of the ecological situation caused by environmental pollution. As a rule, the removal of rot occurs at the stage of round timber harvesting. Therefore, during harvesting, most of the wood with heart rot continues to remain in the forest. In addition to littering the area, it continues to infect sound wood. At the same time, together with the wood affected by rot, the sound sapwood, which has good strength characteristics, is also removed. A method for processing round timber with heart rot into elements of load-bearing structures is proposed. In particular, a technological scheme for manufacturing I-beams from such timber has been developed for low-rise house construction. Corner elements are produced as a result of cutting round timber and removing heart rot by milling. The corner elements are dried in clamped state using special devices. Then they are glued together to obtain beams with a cross-section in the form of an I-beam. A set of equipment for the processing round timber with heart rot was selected. The paper presents the results of calculating the costs for organizing the production. The effectiveness of the technological project is evaluated using the method of discounted cashflows by the following indicators: net present value, profitability index, and discounted payback period. The assessment results confirm the effectiveness of the production organization of load-bearing structures made of round timber affected by heart rot. The processing of wood that remains in the forest into elements of building structures not only increases the wood reserves for construction, but also creates conditions for improving the ecological situation in forest areas. For citation: Toropov А.S., Byzov V.Е., Toropova Е.V., Sergeevichev А.V., Sazanova E.V. Cutting of Round Timber with Heart Rot to Structural Lumber. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 6, pp. 160–172. DOI: 10.37482/0536-1036-2021-6-160-172