July 30, 2012

Mass timber construction use growing

MCFARLAND MARCEAU ARCHITECTS LTD.

The North Shore Credit Union Environmental Learning Centre utilizes cross laminated timber floor panels over structurally reinforced glulam floor beams.

JEAN SORENSEN

correspondent

Mass timber construction is reaching a critical juncture as contractors are feeling more comfortable using large prefabricated panels for wall, floor and roof construction.

“We have really gone full circle,” said George Rossi, a partner in Surrey’s D.G.S. Construction, whose family started in construction in the 1960s when “everything was wood.”

The difference, said Rossi, is the wood products and their use. There are more composite wood products and more prefabrication to compress construction time. It has been happening in Europe for 40 years, he said.

“We have been slow to adapt them here,” he added.

D.G.S. Construction is the company that built the $5.8 million North Shore Credit Union Environmental Learning Centre, one of three wood buildings being showcased by the forest industry and the B.C. government for use of wood innovation design and products.

The Environmental Learning Centre utilizes cross laminated timber (CLT) floor panels over structurally reinforced glulam floor beams, penetrated to hide ducting. Glulams were also used as roof beams.

The other two are Elkford Community Conference Centre and the City of North Vancouver Civic Centre renovation.

The Elkford Centre is the first in North America to use CLT panels in a commercial application on sheer walls.

The North Vancouver Civic Centre is North America’s first combined concrete slabs and a laminated beam floor system. All three structures include prefabrication.

Rossi recalled when most schools were wood and as recently as a decade ago, his company built four wood schools in the Lower Mainland.

But, wood fell from favor, replaced instead by concrete and steel, deemed a faster mode of construction.

However, the ability to prefabricate wood elements has quickened the construction process and Rossi describes it as similar to tilt-up concrete.

Today, D.G.S. is working on another wood elementary school, near the University of B.C.

Architect John Hemsworth of McFarland Marceau Architects Ltd., who designed the learning centre, said there is a perceivable shift happening with wood.

While contractors tend to stay with what they know, they are now responding to the public’s interest in green building.

“Contractors are becoming more comfortable with wood,” he said, adding this is important in building a team approach to a project.

“The sustainability aspect – and wood is known for carbon sequestering – is a big part of the discussion,” he said.

The three projects are only the tip of the iceberg.

Structurlam Products Ltd., which supplied the learning centre’s floor panels and Elkford’s CLT wall panels, last year opened its new CLT plant in Okanagan Falls.

Its Penticton plant manufactures glulam beams, Parallam, as well as sawn timber. Vancouver branch manager for international sales Colin Chornohus, said that since opening, the new CLT plant has supplied a dozen projects.

Structurlam deals with contractors during the construction phase, he said.

He’s noticed that some contractors are more willing to embrace change.

The Elkford Community Conference Centre is using CLT panels as the shear walls to resist the high wind load for the building, as a valid alternative to concrete and steel.

Glulam and laminated veneer lumber beams were used to support the CLT walls or perimeter columns.

“We supplied the glue-laminated beams and trusses, and the CLT panels,” said Bill Downing, president of Structurlam. These panels were used for the roof and exterior wall cladding because of their insulation properties.

General manager Michael Marshall of StructureCraft, which supplied the laminated strand lumber (LSL) roof panels for the North Vancouver civic centre renovation and the roof panels for Richmond’s Olympic Oval, also sees contractors’ growing acceptance of wood.

There is a re-education of the benefits of wood occurring as more wood is used and misconceptions tumble such as fire concerns, he said.

“Wood performs well in a fire,” he said, adding that it forms a char layer that delays deeper burns.

“A really big part is the environmental aspect,” Marshall said. “We have learned that the total carbon footprint of timber is less than steel and concrete.”

The floor system, within the civic centre renovation joining city hall to the library, consists of glulam post beams, replacing steel, to support the concrete floor slab, a first in North America.

Marshall said there are only three or four companies in the world that combine structural engineering design with construction facilities such as StructureCraft.

“It is so critical to design the way we do,” he said.

Marshall said on the LSL roof panels were built for general contractor Stuart Olson Dominion and the company simply flew them into place on the glulam timber frame using a crane.

“It is one way to compress the construction schedule,” he said.

MCFARLAND MARCEAU ARCHITECTS LTD.

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