Yarrow EcoVillage: a community living and working in
harmony with neighbours and nature

Located in Yarrow, Chilliwack, in Southern BC, Yarrow EcoVillage is a co-operative with 25 acres of property. Organic farmland forms 20 acres of the site while the remaining 5 acres has been zoned as an ‘ecovillage’. The philosophy behind the whole development is "A community living and working in harmony with neighbours and nature". To achieve part of this goal, the buildings are designed to be as sustainable as possible within the limits of current knowledge and technology.

The ecovillage, when completed, will have businesses, cottage industries, a learning centre, guest ranch cottages, and a mix of
multi-family and live/work accommodation, all centred around an organic farm.

Yarrow Ecovillage under construction

Other features of the development include a solar aquatic wastewater treatment facility along with solar and wind energy generation.

Associated Engineering is responsible for the structural engineering components of this development and has worked closely with both the other designers and the owner to achieve the goals.

Phase 1 of the proposed development of Yarrow EcoVillage is two duplex residential homes which form part of the village. Because of the innovative approach, the buildings were treated under Part 4 of the British Columbia Building Code rather than the general guidelines of Part 9.

The duplex building is a two story, timber frame building on 1.2 metre high concrete walls. The concrete walls form a crawl space underneath the main floor and also lift the ground floor to a level stipulated by the development permit. The main external walls will be constructed in cordwood. Cordwood is essentially the use of 40.6 centimetre (16 inch) lengths of timber logs stacked and placed on mortar to provide a 40.6 centimetre thick wall. Because of the unusual nature of this construction, it was important to the client to expose the ends of the logs on both faces of the wall. The structural challenge was to provide both a gravity force resisting system and a seismic / lateral force resisting system that allowed the use of timber framing and cordwood to the satisfaction of the end users. Other issues that had to be considered were the use of a relatively heavy roof covering (recycled tire ‘shakes’), detailing of the shrinkage from the timber frame, and high flyash content within the concrete.

The final adopted structural system is as follows:

• Gravity loads are carried through structural timber rafters and joists to heavy structural timber beams and posts framed in a traditional manner to allow for shrinkage effects. Wall and column loads are taken into the concrete foundation walls and hence into the spread footings.
• Lateral loads, where seismic force is critical, are carried through diaphragms at roof and floor levels into shear walls formed
  within the depth of the heavy timber framing. To restrain the cordwood infill, ‘key’ details have been formed to allow for shrinkage, but to retain the infill panels under lateral forces. All timber framing is secured to the concrete foundations with proprietary anchors.

Project Manager, Mark Porter advises, “Construction is currently underway and the first phase of the project is scheduled for completion in early 2009. The next phase of the work will involve additional units and the rehabilitation of existing buildings on the site, including an historic dutch barn.”