Optimizing profile geometry to reduce the checking, shelling and cupping of profiled softwood deck-boards exposed to natural weathering
department or school: Forestry, Faculty of
data provider: DSpace
degree campus: UBCV
creator: Leung, Lukie Hon
issued: 2020-12-24T19:30:33Z
issued: 2020
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: Wooden deck-boards are susceptible to surface checking and distortion during weathering. Surface profiling is an effective physical pre-treatment to reduce the checking of boards, but it is less effective at reducing cupping, unless it is also used on the underside of boards. I hypothesize that the checking and cupping of softwood deck-boards exposed outdoors can be significantly reduced by optimizing the geometries of surface and sub-surface profiles. To test this hypothesis, I examine the effect of profile geometry and growth ring orientation on the checking and cupping of western larch deck-boards exposed outdoors. Standard and tall rib profiles were significantly more effective at restricting checking than other profile types, particularly when profiled boards were oriented pith-side-up. However, such growth ring orientation made larch deck-boards more susceptible to shelling, a severe defect caused by the separation of growth rings. Confocal profilometry and macro-photography were used to characterize the projection of separated latewood at deck-board surfaces. A negative correlation was revealed between the heights of protruding latewood and growth ring angle to the weathered surface of flat larch boards oriented pith-side-up. The number of shelled lanceolate-shaped tips at the peaks of profiled boards was more common in boards with rib profiles particularly those oriented pith-side-up. I conclude that profiled larch boards should be oriented bark-side-up rather than pith-side-up. Hence, there was a need to develop different sub-surface profiles to distinguish pith- and bark-sides of boards so that boards can be correctly oriented in decks with their bark-side facing uppermost. Pacific silver fir and western hemlock boards were chosen to test sub-surface grooving as an alternative to sub-surface profiling because previous studies had optimized surface profiles for both species. There was an unexpected effect of number of grooves on the cupping of hem-fir board…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/76899
note: OPTIMIZING PROFILE GEOMETRY TO REDUCE THE CHECKING, SHELLING AND CUPPING OF PROFILED SOFTWOOD DECK-BOARDS EXPOSED TO NATURAL WEATHERING by Lukie Hon Leung B.Sc. in Wood Products Processing, The University of British Columbia, 2018 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Forestry) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) December 2020 ©Lukie Hon Leung, 2020 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the thesis entitled: Optimizing Profile Geometry to Reduce the Checking, Shelling and Cupping of Softwood Deck-boards Exposed to Natural Weathering submitted by Lukie Hon Leung in partial fulfillment of the requirements for the degree of Master of Science in Forestry Examining Committee: Professor Philip D. Evans, Wood Science Supervisor Dr Christopher Gaston, Wood Science Supervisory Committee Member Dr Rod Stirling, FPInnovations Supervisory Committee Member Dr Harry Nelson, Natural Resources Management Chair of Examination Committee Dr Adnan Uzunovic, FP Innovations Examiner iii Abstract Wooden deck-boards are susceptible to surface checking and distortion during weathering. Surface profiling is an effective physical pre-treatment to reduce the checking of boards, but it is less effective at reducing cupping, unless it is also used on the underside of boards. I hypothesize that the checking and cupping of softwood deck-boards exposed outdoors can be significantly reduced by optimizing the geometries of surface and sub-surface profiles. To test this hypothesis, I examine the effect of profile geometry and growth ring orientation on the checking and cupping of western larch deck-boards exposed outdoors. Standard and tall rib profiles were significantly more effective at restricting checking than other profile types, particularly when profiled boards were orien…
has type: Thesis/Dissertation
date issued: 2021-05
is shown at: 10.14288/1.0395401
language: eng
degree discipline: Forestry
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/76899