Results of the recently approved machine control grading settings for Douglas fir in the Republic of Ireland and the UK have shown that the species can be graded to C18, and higher strength classes, and while there is a relatively high proportion of low strength timber, useful yields of grades up to C35 can be achieved. Large differences were found between subsamples, but it is believed that this is not a geographical difference between Ireland and the UK, but a feature of the representative sampling, and consequence of much more localized variation in timber quality.
Gil-MorenoD, Ridley-EllisD, McleanP.2016. Timber properties of Noble fir, Norway spruce, western red cedar and western hemlock grown in Great Britain. Research Note FCRN026.Edinburgh: Forestry Commission.
7.
MooreJR, LyonAJ, SearlesGJ, LehnekeSA, Ridley-EllisDJ.2013. Within-and between-stand variation in selected properties of Sitka spruce sawn timber in the UK: Implications for segregation and grade recovery. Ann For Sci. 70(4):403–415. doi: 10.1007/s13595-013-0275-y
8.
PicardoV.2000. Quantification of the yields of Irish grown Sitka spruce in the new CEN strength classes. Dublin: COFORD.
9.
Ridley-EllisD, AdamsS, LehnekeS.2018. Some thresholds for grading British grown spruce to optimised strength classes using longitudinal resonance.
10.
Ridley-EllisD, StapelP, BañoV.2016. Strength grading of sawn timber in Europe: an explanation for engineers and researchers. European Journal of Wood and Wood Products. 74(3):291–306. doi: 10.1007/s00107-016-1034-1
11.
ViguierJ, BourreauD, BocquetJ-F, PotG, BléronL, LanvinJ-D.2017. Modelling mechanical properties of spruce and Douglas fir timber by means of x-ray and grain angle measurements for strength grading purpose. Eur J Wood Wood Prod. 75(4):527–541. doi: 10.1007/s00107-016-1149-4
12.
Standards:
13.
CEN. 2002. Moisture content of a piece of sawn timber—Part 1:Determination by oven dry method. EN 13183-1:2002.: European Committee for Standardisation, Brussels, p. 5.
14.
CEN. 2003. Round and sawn timber. Nomenclature of timbers used in Europe. EN 13556:2003. European committee for standardisation, Brussels, p 108.
15.
CEN. 2012a. Structural timber. Strength classes. Assignment of visual grades and species. EN 1912:2012. European Committee for Standardisation, Brussels, p 17.
16.
CEN. 2012b. Timber structures - strength graded structural timber with rectangular cross section. Part 2: Machine grading; additional requirements for initial type testing. EN 14081-2:2010 + A1:2012. European committee for standardisation, Brussels, p 26.
17.
CEN. 2012c. Timber structures—structural timber and glued laminated timber—determination of some physical and mechanical properties EN 408:2010 + A1:2012. European committee for standardization, Brussels, p 38.
18.
CEN. 2018. Structural timber-determination characteristic values of mechanical properties and density. EN 384:2016 + A1:2018. Brussels: European Committee for Standardization.
19.
Grading reports (confidential):
20.
Ridley-EllisD, Gil-MorenoD.2018a. Derivation of Viscan Compact and Viscan portable with balance grading machine settings for Douglas fir (IE & GB, C classes), TG1/201804/14rev1 (approved grading report).
21.
Ridley-EllisD, Gil-MorenoD.2018b. Derivation of Viscan Plus machine settings for Douglas fir (IE & GB, C classes), TG1/201804/15rev1 (approved grading report).
22.
Ridley-EllisD, Gil-MorenoD.2018c. Derivation of Viscan and Viscan portable without balance grading machine settings for Douglas fir (IE & GB, C classes), TG1/201804/17rev2 (approved grading report).
23.
Ridley-EllisD, Gil-MorenoD.2018d. Derivation of MTG grading machine settings for Douglas fir (IE & GB, C classes), TG1/201804/25rev (approved report).
