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Grading of British spruce cladding battens by ring width for density, fastener performance and fire

Ridley-Ellis, Dan

Authors



Abstract

The UK has a British Standard for external timber cladding, BS8605-1, in which support battens are defined as timber components of a section, grade, and durability, suitable for supporting external timber cladding. The term includes both battens (which are used horizontally or diagonally) and counter battens (which are only used vertically). Clause 17 states that where the density of timber for support battens is required, this should be determined in accordance with EN384. This is because design of support battens might involve structural calculation, for which a characteristic density value (5th percentile, with appropriate adjustments) is necessary. This characteristic density is conservative on the side of underestimating real density, since this density value is used as an estimator for fixing performance and charring rate (fire resistance). Minimum mean density, which is calculated from characteristic density (a factor of 1.2 in EN384), is used as a threshold for reaction to fire classification without need for further testing.
This paper examines the effectiveness of grading by ring width for characteristic density, using UK and Irish grown British spruce as the case study. British spruce has relatively wide growth rings compared to other common timbers. There is a separate question as to whether ring width affects fastener performance and charring rate separately from density, but for this paper it is assumed that the equations given in EN384 and EN1995-1-1 are correct for any ring width.

Citation

Ridley-Ellis, D. (2019). Grading of British spruce cladding battens by ring width for density, fastener performance and fire. In Proceedings of the 15th Annual Meeting of the Northern European Network for Wood Science and Engineering

Conference Name 15th Annual Meeting of the Northern European Network for Wood Science and Engineering
Conference Location Lund, Sweden
Start Date Oct 9, 2019
End Date Oct 10, 2019
Publication Date Oct 9, 2019
Deposit Date Sep 11, 2021
Publicly Available Date Mar 29, 2024
Book Title Proceedings of the 15th Annual Meeting of the Northern European Network for Wood Science and Engineering
Public URL http://researchrepository.napier.ac.uk/Output/2801277
Publisher URL https://ltu.diva-portal.org/smash/get/diva2:1360939/FULLTEXT01.pdf