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Douglas-Fir Optimised Engineered Lumber (OELTM) Trial

By Doug Gaunt, July 2016.

Download SWP-T007 (pdf)

Executive summary

The OELTM (Optimised Engineered Lumber) technology produces structural products with known, uniform and reliable properties. There is financial advantage derived from the fact that all the merchantable OELTM production output is certified structural grade (no downfall products), this compares with the output from traditional sawmilling where not all production achieves certification as structural grade product.

Wood Engineering Technology Ltd (WET) hold patents of the OELTM process and are currently inthe process of commercialising the OELTM product. WET was sub-contracted by Scion to undertake this Douglas-fir trial for the Special Wood Product Partnership.

The intention of this project was to complete a scoping only study that took Douglas-fir thinning material through the OELTM process followed by an assessment of the mechanical properties with the high level OELTM economics developed.

Ernslaw One supplied 3m3 of Douglas-fir thinning’s logs these were young with an average age of 15 years, small end diameters (over bark) ranged from 19.5 – 36.5cm. large end diameters (over bark) ranged from 27.0 – 42.0cm, with an average Hitman value of 3.3km/sec. Wood Engineering Technology Ltd (WET) processed these into 71 pieces of 90x45x2930mm OELTM and these were then supplied Scion for mechanical testing.

The results of the mechanical testing showed that the Douglas-fir OELTM achieved the strength and stiffness properties of the New Zealand structural grade SG8. SG8 is the common grade used in house framing.

The economic comparisons indicated the superior results of using OELTM technology in converting 15-year-old average age production thinning Douglas fir logs into SG8 structural lumber (glulam), when compared with a saw log from full thirty-year rotation Radiata pine. This comparison applies to both Douglas fir logs that would normally be graded to saw logs or to pulp logs

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