Expanding 2×4 into Large Span Commercial Buildings

Two prominent wooden warehouses were recently designed and built by platform frame construction (total floor area for each building is approximately 1,400 m²) in an economical and environmentally friendly way in Fukushima Prefecture. The large warehouses, both 20 m wide and 70 m long, were built with structural wood product members (composite double beam girders, i.e. box beams) in order to construct a roof span of 20 m, while the walls were assembled using dimension lumber. The volume of wood used in these two warehouses, including plywood sheathing, is about 550 m³, in which 350 m³ of this amount was Canadian SPF dimension lumber. This project was initially proposed to be constructed in steel, but it was redesigned and constructed in wood to reduce the foundation construction cost, and in order to realize a shorter construction period. The warehouses are owned by Ichiro Co., Ltd., designed by Sasaki Architect Office and the wooden structure was engineered and supplied by Japan Kenai Co., Ltd. The warehouses are a great example and highlight the possibilities of large-scale wooden commercial buildings requiring longer spans. Construction cost for these buildings was 495,000 yen per tsubo – a Japanese unit of area equal to approximately 3.31 m². In COFI’s recent market research into non-residential construction, logistics centres, warehouses and manufacturing facilities were identified as the most promising in terms of untapped market potential for wood construction.

Exterior and interior photos of Ichiro Warehouse in Fukushima Prefecture

Japan Corona Virus Update

By mid-May the Coronavirus outbreak is showing signs of receding in Japan. The number of new cases nationwide peaked at the 650 level in mid-April. By mid-May, Tokyo has consistently reported less than 10 new cases daily. The state of emergency has now been partially lifted in most prefectures but remains in place in Tokyo and Hokkaido. The economic impact is starting to take a toll. Foreign arrivals to Japan plunged 93% in March and 99.9% in April with the nation virtually locked down to international travel. Consumers and businesses are plunging. Current forecasts estimate that Japan’s annual GDP may shrink 5% in 2020.

The Aesthetic Appeal of Wooden 2×4

Manten Social Welfare Corporation builds another senior home using platform frame construction. This is the third 2×4 elderly care project the owners, Mr. & Mrs. Yamada, have built in Japan since participating in COFI/Canada Wood Japan’s Elderly Care Tour Mission to Canada ten years ago. Their latest project was constructed in Nagahama City, Shiga Prefecture and opened on April 24, 2020. It is a two-storey 2×4 building with a total floor area of 1,240 m², in which about 170 m³ of wood products were used, and to keep construction costs down, the building’s design is straightforward and clean. The concept for this care home is to relax and unwind in “the warm feeling of wooden 2×4” and “the aesthetic appeal of nature supporting wellness,” for not only the residents but staff as well. The benefits of living in a 2×4 home are something the Yamada’s know first-hand, as they live in a three-storey custom 2×4 home that they had built in Osaka in 2014. It is lovely to see the passion they have for 2×4 and moreover, how they enjoy sharing it with others. If you are interested in reading past blog articles on their other 2×4 endeavours, please visit links below.

Two, Three & now Four-storeys . . . (February 1, 2016)



Proud New Home Owners (April 1, 2014)



Wood Nursing Home Opens (September 5, 2012)



Exterior photo of Community Nursing Home Menten Takatsuki


NLT Technical Project Report Published

This past year COFI/Canada Wood Japan worked with the Japan 2×4 Home Builders Association to facilitate the spread of large-scale wooden buildings using Nail-Laminated Timber (NLT) in horizontal diaphragms such as roof and floor structures. One of the goals was to confirm 1-hour quasi fire-resistive performance for floor assemblies and 30-minute quasi-fire resistive performance for roof assemblies. Regarding structural performance, the research required NLT configurations with butt joints to evaluate and compare performance versus NLT without butt joints to ensure all potential structural weaknesses are fully understood. COFI and the Japan 2×4 Home Builders Association jointly worked to conduct a series of bending tests. These were the 4-point loading bending test to 2×12 and 2×8 Canadian SPF. After collecting the data, we confirmed that our numerical modelling works accurately on the rotational rigidity at the butt joints. Those test results were compiled in a 508-page report booklet. This report has recently been completed and released and will serve as a resource for structural engineers designing NLT diaphragms.

Japan Housing and Non-residential Starts: Jan&Feb 2020

January’s total housing starts dropped 10.1% to finish at 60,341 units for the seventh consecutive monthly decline. Owner-occupied housing declined 13.8%, and rental housing fell 2.5%. Wooden housing fell 11.2% to 33,849 units. Post and beam starts fell 11.1% to 26,055 units. Wooden prefab fell 17.9% to 781 units. Platform frame starts posted a 10.8% decline to 7,013 units. By housing type, the breakdown in platform starts is as follows: custom ordered homes dropped 14.5% to 2,092 units, rentals declined 7.3% to 3,939 units and built for sale spec homes decreased 15.5% to 967 units.

February total housing starts continued to trail year prior results with a 12.3% drop to finish at 63,105 units. Owner-occupied and rental housing fell 11.1% and 18.9%, respectively. Wooden housing fell 10.4% to 35,824 units. Post and beam starts fell 10% to 27,778 units. Wooden prefab ventured further into niche territory, falling 12.2% to 761 units. Platform frame starts dropped 11.9% decline to 7,285 units. By housing type, the breakdown in platform starts is as follows: custom ordered homes declined 9.8% to 2,153 units, rentals declined 12% to 4,109 units and built for sale spec homes decreased 13.3% to 1,007 units.