Timber Curtainwall Makes its Move in the North American Market

By Ellen Rogers

North America is shelling out big bucks in energy costs, with the built environment accounting for nearly half. According to the U.S. Department of Energy, in the U.S., commercial and residential buildings account for approximately 40% of the nation’s total energy demand, costing more than $380 billion in energy annually. It seems that everyone is looking for the means and methods to reduce these escalating costs. Even New York Mayor Bill de Blasio weighed in when on Earth Day he suggested “banning” the use of glass in buildings (See articles “Bronx Cheer from Bill D.” and “Gridlocked” on pages 6 and 60 of the May 2019 issue of USGlass magazine, respectfully).

The answers, however, aren’t necessarily about banning a certain product. Instead, using alternative materials could be the key to a high-performance, sustainable built environment. And one possibility is wood.

In January of this year the International Code Council (ICC) approved a set of proposals that would allow tall wood buildings—up to 18 stories—as part of the 2021 International Building Code (IBC). The state of Oregon also passed similar legislation that would allow for mass-timber high rises.

Earlier this year code consultant Thom Zaremba said this change will bring “… a dynamic shift in the next decade in tall wooden buildings … A shift in aesthetics involving glass inside and out because of the [move] toward tall wood buildings.” He noted that windows will fit into this move well because they won’t just be for views out of the building, but also for viewing in the building.

While the code changes don’t directly impact curtainwall and glazing systems specifically, they indirectly create a friendlier design environment for wood and wood curtainwall.

“The codes allow for larger mass timber structures, a trend that we see especially strong in the Pacific Northwest and in Boston and the surrounding areas,” says Renee Ewing, commercial sales manager for Reveal Windows & Doors, a division of Pacific Architectural Millwork (PAM) located in Brea, Calif. “The growing acceptance of timber as a viable and sustainable building material is helping to change the aesthetics of these buildings and bringing more attention to the benefits of wood for larger commercial buildings. This influences how design teams approach the buildings as a whole.”

Timber curtainwall is more common in Europe compared to North America. Viviane Chan, director of sales and marketing for Unicel Architectural in Quebec, says North America is often behind Europe.

“Timber curtainwalls have been used in Europe for probably the last 30-40 years and they are still not well-known products here in North America,” she says. “There’s still a lot of getting used to these types of systems.”

But market awareness is changing and more manufacturers are bringing products to market—for a lot of good reasons. Timber systems provide aesthetics, as well as high-performance and sustainability attributes—important details in light of increasingly stringent energy codes and building requirements. Bringing a new product to market, particularly one that comes at a premium cost, isn’t easy. The opportunity is there and manufacturers say education will be key in increasing awareness.

Reasons for Wood

Wood building products, windows in particular, aren’t new. In single-family homes, for example, wood is one of the most appealing window options, especially given the warm aesthetic environment it creates. The same can be said of commercial construction and new developments in timber innovations. This is helping drive traditionally residential window manufacturers into the realm of wood curtainwall for commercial, as well
as high-end residential applications.

Ewing sites aesthetics as one of the top reasons architects are becoming more and more interested in wood curtainwall. It’s also sustainable and environmentally friendly.

“The life-cycle effects of timber curtainwall on our environment are a fraction of those from aluminum,” she says. “Also, wood, unlike aluminum or steel, has natural insulating capabilities that promote better interior comfort and temperature control.”

Reveal manufactures a timber curtainwall system with wood interior. From the exterior, it resembles aluminum, while the wood interior can be milled out of any species, and is engineered according to the structural and performance needs of the opening. The company has partnered with the German company Raico to create these curtainwall systems.

Unicel manufactures traditional aluminum curtainwall systems, as well as wood ones. Last year the company acquired all the assets of IC2 Technologies Inc., which specializes in the fabrication of high energy-efficiency timber curtainwalls. It also works with Raico. Chan agrees that wood provides many performance benefits, especially given its thermal performance attributes. “[Our wood curtainwall] is a highly energy efficient system that reduces heat gain/loss and wood is one of the most thermally efficient [building products] in the world,” she says, adding that it also uses a lot less energy to produce.

“The amount of energy used to produce an aluminum extrusion to fabricate traditional curtainwall requires mining, extraction, melting, etc. There are a lot of steps to get to the final product,” she says. “Wood is a renewable resource and it requires a lot less energy to transform from a tree to a curtainwall in a building. That means you’ve polluted the environment less, and also by choosing wood, you remove some carbon dioxide from the atmosphere instead of emitting some more,” Chan says, adding that another feature of timber curtainwalls is that they can be load bearing.

“This results in a much more efficient use of material for any kind of project. Timber curtainwalls can also act as the structure of a building. You can build with much longer spans without the need for steel reinforcement or additional support structure compared to aluminum curtainwalls,” she says.

Greg Header, president of Solar Innovations in Pine Grove, Pa., agrees that wood curtainwall offers a number of performance and aesthetic benefits.

“It can give you great thermal performance; it can tie into a building design better, especially if it’s being used in a timber frame/wood building, where it can create a unified statement.”

He adds that its use is not recommended in applications where wood is on the exterior due to exposure to the elements.

“You have to be aware of that as a design consideration,” he says. Wood or aluminum caps are available as an option for the exterior, and some projects do opt for unfinished wood exterior caps to weather over time.

Andrea White is the director of architectural sales for Sierra Pacific Windows, a division of Sierra Pacific Industries located in Red Bluff, Calif. She says the structural capabilities of wood are also a benefit that’s sometimes an afterthought.

“With a large span of traditional curtainwall, some type of structural support (typically steel) would need to be added. The glulam timbers can become the structural support, so no additional steel is needed,” she says, adding, “Wood is the only building material we can grow, so it hits the bullseye on the sustainability target, with the additional benefit of sequestering carbon.”

Resistance to Change?

New products don’t always have an easy time entering a new market and in many cases are faced with resistance, especially when they cost more compared to what’s already readily available.

“There will always be a scare factor [with something new] and that drives
the cost up because [the industry isn’t yet] familiar with it,” says Chan.

According to Header, the more suppliers, architects and installers understand the products, the more costs come down.

“When we first started we all needed to be able to do more cost effectively;
at the time the cost per square foot was probably double that of aluminum
curtainwall. A lot of that was due to not everyone understanding the most efficient, effective design of it …” he says. “Now we’re seeing the manufacturing processes being improved and wood curtainwall manufacturers and wood suppliers becoming more competitive.”

Collaboration and communication upfront, he explains, are essential to ensuring market acceptance.

“If [a contract glazier] is doing its first wood project the company needs to understand the architect’s intent, and collaborate with the fabricator to work together and make changes while there’s time in the interest of cost, installation, etc. Having collaboration upfront is the most important thing. And if you’re getting involved, you need to own it and truly understand it because that leads to a better project in the end. If it’s a beautiful finished project it tends to be something people will embrace.”

Kapiloff ’s Glass is a contract glazing company in Adams, Mass., that’s had some experience working with wood curtainwall. Dante Birch, senior project manager, says for installers, when working with an organic material, specific attention is required throughout the quality control process.

“Raw material costs and consideration of the product’s material and finish during installation add to labor cost,” he says. “There is no touch-up paint to fix a 14-inch white oak beam.”

Speaking of wood vs. aluminum, Ewing says wood poses unique considerations compared to aluminum. For example, mullions can be milled from many different species of wood and with a variety of finishes. “Every single mullion is custom,” she says.

Another challenge, Chan says, is that a lot of glaziers already distribute their own aluminum systems, so the timber systems compete directly with what they already offer. “And because they’re more familiar with aluminum, they tend to push for that instead. They have comfort in working with what they know and so wooden curtainwalls tend
to be eliminated.”

She adds that fire ratings are also sometimes questioned.

“There are some projects that require fire-rated curtainwalls and there’s a misconstrued notion that wood curtainwalls will burn [quickly]. That’s not true,” says Chan.

According to the American Wood Council’s publication, Calculating the Fire Resistance of Wood Members and Assemblies, “The superior fire performance of timbers can be attributed to the charring effect of wood. As wood members are exposed to fire and the wood begins to burn, a char layer is formed. The char layer acts as an insulator and protects the core of the wood section. Thus, wood members can be designed so that a sufficient cross section of wood remains to sustain the design loads for the required duration of fire exposure. A standard fire exposure is used to calculate the fire resistance.”

Learning Curves

For many contract glaziers, working with wood will be a new scenario. Others may transition easily. Ewing says she’s been surprised at how comfortable contract glaziers have been with the system, because it’s similar to what they’re used to.

“The biggest thing is getting the initial information—the wood species, and how to tie in the curtainwall with the rest of the building,” she says. Ewing says that working with a wood system is a much longer process from start to finish.

“I’ve been working on some projects for over a year. Even once they’re under contract, it will be another nine months before we start manufacturing,” she says. “It’s another dimension to the complexity that the glaziers go through. Lead times do take longer.”

Birch says from the start, the design process and required attention to detail take a front seat as the driver of the project.

“This is due to the tactile nature of the material and that the end result is often a central design focal point of the architectural experience,” he says. “[That brings] a heightened attention to detail, making the submittal and shop drawings process longer than that of an off-the-shelf product.” In addition, he says the product’s ability to be customized adds further design options that may take longer to coordinate.

“Because the system has more opportunities for custom design and unique accessories, there’s more flexibility and, as such, it’s more of a collaboration-focused process compared to other aluminum off-the-shelf options,” Birch adds.

Chan points out that suppliers will definitely need to educate both architects and contract glaziers to help get them comfortable with these products.

“Our system is factory-fabricated and assembled and delivered in modules so it’s easier to install,” she says.

Header says his company also takes steps to make the process simple for the installers.

“We pre-assemble and make things as modular as possible so it’s easier for the customer and we do video mock-ups. Also depending on the design, we’ll bring architects into our facility for testing and approval of visual mock-ups.”

The move toward wood also could mean new opportunities for contract glaziers. Chan says, in some cases, wood curtainwall installations are handled by carpenters or trades accustomed to working with wood.

“Glaziers traditionally work with aluminum and glass, so it can be an uncomfortable shift for them to work with these products,” she says.

Header has seen this as well, and says when working with contract glaziers they’re often teaching them the fine details of what a carpenter does.

These experts all agree that early collaboration and communication are important on these projects.

“Partner with a provider and really look at what [this job] takes up front … and work together to understand what it will take and totally comprehend the whole scope,” says Header.

Ellen Rogers is the editor of USGlass magazine. Follow her on Twitter @USGlass and like USGlass on Facebook to receive updates.

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