Steel vs. Wood

New products on the market make choosing between steel and wood just a little bit more difficult
 
At times, construction can be a confusing industry, with steel seemingly transformed into would-be wood and wood assuming a steely demeanor.

Some wood-based products seek to compete with structural or performance characteristics of concrete, masonry or metal. Alternatively, metal or synthetic construction components are often finished to give the feel or aesthetic of wood and stone.

Canada has been fairly slow to add wooden looks to metal and composite siding. European-inspired composite soffit-like panels, with such a woody appearance, have found their way onto a few Alberta buildings-notably renovations to Edmonton's Clarke Stadium. Other efforts to achieve a woody appearance have entailed "sublimating" or pulling a transparent wood-grain cover over and then re-baking powder-coated aluminum extrusions or other components, such as window frames.

However, the Forest Products Association of Canada (FPAC) is championing new applications that allow wood to reach higher and wider. It could let wood challenge steel and concrete as a structural material-even for large, multi-storey buildings.

In Edmonton, Lenmak Exterior Innovations Inc. is manufacturing a new steel-based NaturClad siding that looks convincingly like wood. Lenmak owner Ray Turner liked the wood look on siding, but felt products on the market were overpriced and unsuited for Canada's climate or required overly complex manufacturing.

Turner searched for alternatives better suited to Canadian budgets and environments and found the inspiration for his company's NaturClad in "printed paint" stencilling techniques, which apply wood-grain patterns to steel furniture and metal garage doors.

In 2008, Lenmak began using printed paint to deliver a weathered copper, zinc and even rust appearance to a steel-based siding. The Morinville, Alta., Civic Hall and Community Library building is among those where Lenmak has supplied such StrataClad panels.

Lenmak manufactures the siding panels at its $4-million, fully automated production line in western Edmonton. The company buys huge coils of print-painted steel product then shapes it into customized siding units to fit clients' requirements. Lenmak plans to offer a variety of shades for NaturClad, which currently comes in a walnut wood grain and in three shades-natural walnut, mahogany and light hickory.

"We're trying to give the option of that real wood look with the 40-year paint warranty," explains Turner.

NaturClad is entirely Canadian produced, from the substrate through the paint system, and finally to Lenmak's custom fabrication. Besides the aesthetic features, low maintenance and durability, NaturClad has a Class 1 fire rating and can be custom manufactured and delivered within days. NaturClad assembles easily and requires no retraining of installation crews.

While expecting NaturClad to find use on residential structures, Turner also foresees it on commercial and institutional structures, as well as condominiums and certain industrial structures. "Architects," he notes, "are looking for products that have some aesthetic punch."

NaturClad is more versatile and more easily customized than competing products originating in Europe, and, Turner adds, costs "half the money or less" and is price-competitive with acrylic stucco.

Steely competition
If wood-like steel siding amounts to the "most sincere form of flattery," the forest industry is returning the compliment by challenging steel and concrete.

Many forest products have faced declining demand in the last decade. Some of that downturn stems from structural changes, like reduced demand for newsprint, and cyclical challenges, such as the U.S. housing collapse.

This prompted Canada's $57-billion-per-year forestry industry, led by FPAC, to seek new ways to utilize forest resources. An FPAC Bio-Pathways initiative examined novel ways to extract chemical, pharmaceutical and food ingredients, as well as energy, from trees.

Of more immediate impact to construction is FPAC's Construction Value Pathways initiative. Released in February, it studied ways that the solid-woods side of the industry might diversify beyond traditional markets and products. The review looked at current and future trends in global construction-including residential, commercial and infrastructure-in North America, Asia and Europe.

The global scan identified 32 promising, emerging products within the following five wider categories:

  1. Multi-functional panels, including sheathing, insulation, water barrier and structural capacity;
  2. Next-generation engineered wood products;
  3. Fibre-based insulation;
  4. Hybrid building solutions with wood added to steel and concrete structures such as floor decks; and
  5. Exterior application of durable, low-maintenance products.

"A lot of them are commercial or fairly close to being commercialized elsewhere in the world-primarily in Europe," explains FPAC vice-president of regulations and partnerships, Paul Lansbergen.

Lansbergen notes the example of a multi-functional, three-in-one sheathing product in the form of an oriented strand board (OSB) panel that already comes with a plastic vapour barrier on the outside and insulated coating on the inside: "You put it up [on] the outside like you would OSB on your structured wall. It's faster to put up than regular sheathing."

Next-generation products could include engineered wood studs geared toward taller walls, or low-density fibre-based insulation panels, several inches thick. Such products might find application in ceiling structures and partition walls in office and commercial buildings.

Construction Value Pathways is also encouraging hybrid building solutions where wood fills in-in the form of walls, ceilings and floors-a concrete or steel structural skeleton.
Finally, lower-maintenance exteriors could improve upon traditional wood cladding and reposition wood siding competitively alongside ersatz wood products such as NaturClad.

"[Forest products] are really small players on the commercial side," Lansbergen concedes, but that could change with slight modifications to traditional products.
Engineered wood beams allow for the longer spans needed for open-spaced commercial buildings. Other laminated products also hold promise.

Moving on up
Helped by the pioneering efforts of CST Innovations Ltd. of New Westminster, B.C., cross-laminated timber (CLT) is gaining traction in Canada. CLT employs techniques originally developed in Switzerland in the 1990s and borrows a page from thin-veneer plywood production. However, instead of combining sheets of veneer, perpendicularly positioned layers of thicker lumber are glued together. This allows for fabrication of panelling of varying thickness of decks, walls and roofs in dimensions 10 feet high or possibly 60 feet in length.

Ledcor Group is placing CLT panels in the roof of a new Fort McMurray, Alta., airport terminal. In Brantford, Ont., CLT is being used on the roof of the new Wayne Gretzky Sports Centre. Another sports venue, the Richmond Olympic Oval, built for the 2010 Vancouver Olympics, provided an international showcase for wood's structural strength and appeal.

By creating perfectly uniform strength properties comparable to those of steel and concrete, CLT opens prospects for wooden structures to reach new heights far exceeding those permitted by the current National Building Code of Canada (NBCC). Canadian codes generally restrict the height of buildings made from combustible materials to four storeys or less.

That, Lansbergen notes, is lower than the six storeys practical for building stick-frame buildings and considerably below what is feasible with CLT. He notes upward mobility for wooden buildings is part of the debate leading to 2015 NBCC revisions.

Even so, already in the works is a six-storey (27.5-metre) all-wood Wood Innovation and Design Centre on the University of Northern British Columbia's Prince George campus. Some architects believe that, with new products and techniques, wooden structures up to 30 storeys are feasible.

Lansbergen concedes that "cash is still king" and would-be ideas won't readily be adopted unless cost-competitive. He believes that may be achieved through cost-effective systems that save time and manpower during installation.

Some of the potential products identified by FPAC, particularly ones that involve new building systems, will take time to reach market. That's partly because of the need for forest-firm investments, which may come through joint ventures, licensing, takeovers or even buy-outs of and by foreign firms with new technologies. It may also require the restructuring of forestry business models. Industry players may have to see themselves less as commodity producers (as with standardized lumber) and more as manufacturers of ready-to-install products.

Moving beyond being hewers (and planers and sawyers) of wood will bring forest products companies closer to end-users-something that FPAC's Lansbergen sees "requiring a more integrated relationship with architects, engineers and designers."


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