Friday, August 5, 2016

The Making of Engineered Wood (Glulam)

Study tour to the Mill: Between the Forest and Frame!

Date of Visit: August 5th, 2016
Type of Event: Study Tour
Topic: The Making of Engineered Wood (Glulam)
Organization: Zip - O - Log Mills, Inc
Location: Eugene, Oregon
Host: KayCee Hallstrom/ Sales/Scheduler at Zip-O-Log
International Fellows: Abiodun Solanke (Nigeria), Adam Wasiak (Poland), Karishmaa Pai (India), Samantha Kwan (Malaysia), Yu Lei (China)
WFI Staff: Shadia Duery/ International Fellowship Manager, Chandalin Bennett/ Sr Programs Manager

The Pacific Northwest is well known for its forestry and lumber industry which are the mainstay of its construction industry. A prominent part of the supply chain is the processing of these logs into timber products needed for all types of building projects. Our study-tour goal was to gain firsthand knowledge in the processing capacity and handling of logs to dimensional lumber.

Zip-O-Log Mills is a 3rd generation family-owned business founded in 1944 based in Eugene Oregon (2hrs south of Portland). The company has made its great reputation producing high quality products and on-time delivery. The tour was conducted by KayCee Hallstrom, a fourth-generation family member, daughter of one of Zip-O- Log's current owners.


The Mill prides itself in its zero – waste, fully automated production line, capable of processing up to 52 feet long logs. The logs are sourced from SW Washington and NW to Central Oregon throughout the Willamette valley, mostly from private forests. When selecting the logs, ring count and aesthetics matter the most.
Dimensional Lumber ready for shipping

The logs (timber) are delivered to Zip-O-Log log yard where they are scaled and graded by the Columbia River Log Scaling & Grading Bureau (a third party). 

The sawn lumber is graded by Zip-O-Log graders following The Pacific Lumber Inspection Bureau (PLIB) grading guidelines (third-party). Grading allows to segregate boards according to their overall quality: grain direction, length, width, knots presence and defects as well as general appearance.

The logs are singly picked and loaded by a giant grapple machine into a log in feed deck. Each log is milled using scanners and optimization software to determine the most efficient way to cut the log for pre-ordered dimensional lumber.

Through a series of chain conveyors, the log is rolled into step feeders into the de-barker where it is first sprayed with water to remove of dirt and debris as well as to help cooling the debarking machine. After debarking, boards are cut by laser cutting blades. The process is repeated further through four other laser cutting blades until the desired lumber size is achieved while cutoffs are rolled over into the grinder for biomass fuel.

The lumber is trimmed by length and size for final grading and rolled over through a 16 level sorter based on length and grade. Then detailed measures of quality controls are involved. With the forklift the lumber is stacked according to its size and tag. The grading is based on three broad categories: Green, rough and surfaced. Some of the lumber is kiln dried.


Picture showing Finger Joint Timber
‘Glulam’ as is popularly called is manufactured by finger joining lumber along its length and applying adhesive among the ply/members either liquid to liquid or liquid to powder under high pressure. The 'glulam' then undergoes various quality checks and standard testing for strength.


Understanding the processing of a log to dimensional lumber was very intriguing. This adventure left me with the following thoughts:
  • Zip-O-Log milling process is very efficient resulting in a zero – waste operation
  • As the push for environmentally friendly product advances, engineered wood continuously give architects and engineers one less thing to worry about in creating structurally stable and aesthetically alluring designs (innovative mass timber buildings).
  • Developing countries should embrace the unlimited possibilities of engineered wood in creating environmentally friendly designs as well as be open to continuous research in surmounting the inherent challenges in the use of local resources for construction.

Abiodun Solanke is an architect from Nigeria promoting the adaptation of timber framed buildings in his home country. For more information contact him at or after ending the fellowship program in November 2016 at

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