Exteriors and Outdoor Design

Design trends for exterior spaces and four-season rooms

By Elena M. Pascarella, RLA, ASLA

There’s a lot to love about the outdoors, and this course will explore ways that architects and designers can make inviting and comfortable outdoor spaces that link the outdoors to the interior. There are a variety of products and materials that provide options for designing patios, decks, and outdoor rooms, and that provide experiences in outdoor dining, animated outdoor activities such as poolside recreation, or just relaxing and taking in the surrounding landscape. In addition, outdoor living spaces and rooms can greatly increase the appeal of a home, restaurant, or hotel, and thus increase its value and marketability.

Viewing the Outside from Within

One of the ways to link the exterior and interior of a project is through glass. Extending an indoor room to the outside by opening views through glass windows or doors helps to enhance the interior. Expansive windows and doors allow natural light to penetrate into interior rooms as well as provide a visual extension to an exterior space. Natural light penetrating into interior spaces can also reveal textures and patterns through shadows and provides cues as to time of day.

Appropriately selected windows and doors can also create a space that can be used through the four seasons, even in colder climates. Designers should consider the following criteria when selecting an appropriate window or door system to create a four-season space:

• thermal and energy efficiency,
• ability of the system to accommodate design creativity (i.e., curved walls, corners, etc.),
• impact resistance to storms and severe weather,
• security options,
• material durability, and
• ease of system operation.

The window and door product options for creating a visual and physical interface with the outdoors include:

• windows and window systems,
• French doors and pivot doors,
• bifold and folding doors,
• operable glass wall systems,
• horizontal sliding wall systems,
• combination lift and slide door systems, and
• multi-sliding doors.

There are a wide range of material framing systems for windows and door product. Two common systems are all aluminum and combinations of aluminum with wood cladding. The aluminum- and wood-clad frame system provides the reduced maintenance of an aluminum clad finish, plus the aesthetic appeal and warmth of wood. The aluminum is bent and folded over the exterior of the door or window frame to prevent weather from penetrating into the wood frame.

Windows and Window Systems

Windows and window systems are available in various styles and sizes and can be customized to fit the project design. Designers have the option of selecting fixed, casement (inswing or outswing), hopper, awning, sliding, and tilt and turn (inswing only) window products depending on the project requirements. One of the key considerations when selecting a style or type of window is energy efficiency. The National Fenestration Rating Council (NFRC) operates a voluntary program that tests, certifies, and labels windows, doors, and skylights based on their energy performance rating. NFRC labels can be found on all ENERGY STAR-qualified windows, doors, and skylight products. Two major categories that are reviewed by the NFRC with respect to energy performance ratings are Sunlight Transmittance and Heat Gain and Loss.

Windows can gain and lose heat via 1) the direct conduction of heat through the glass or glazing, the frame, and/or door; 2) radiation of heat into or out of the room or building; and 3) air leakage through and around the window and door panels. The U-factor, solar heat gain coefficient (SHGC) and air leakage are evaluated by the NFRC to measure and rate the energy performance of windows, glass doors, and skylights. The U-factor is the rate at which a product conducts non-solar heat flow. The lower the U-factor, the more energy efficient the product.

The ability of glazing to transmit sunlight is measured and rated according to the visible transmittance (VT) and the light-to-solar gain (LSG). A product with a higher VT rating transmits more visible light. The LSG provides a gauge of the relative efficiency of different glass or glazing types in transmitting daylight while also blocking heat gains. For example, window glazing with the newer second-generation low-e coatings are able to maintain a low U-factor and are also able to reflect solar near-infrared radiation, thus reducing the total solar heat gain coefficient (SHGC) while still providing high levels of daylight transmission.¹

Another example of an energy-efficient window product is a thermally broken aluminum window. The benefits of thermally broken aluminum windows include warmer winters, cooler summers, and a more comfortable living environment. The design of a thermally broken aluminum window includes a polyamide insulator between inner and outer aluminum faces. The result is a permanent thermal barrier that effectively fights energy transfer between the inside and outside and vice-versa.²

Providing Both Views and Access to the Outdoors Using Door Systems

French Doors and Pivot Doors

French doors can serve as both entry doors and as views to the outside. They are also ideal for creating a smooth flow of pedestrian traffic between the outdoors and indoors. French swing doors using tempered glass can provide panoramic views to the outdoors from inside any home or building.

French doors operate by swinging out or by rotating on standard hinges. An optional multi-point locking mechanism allows the door panel to operate easily even when the panel is oversized and heavy. French doors are available with standard hinges or pivot hardware. As the panels are high-capacity in terms of weight and endurance, there is an opportunity for a large swing door that may exceed 70 square feet in a single panel. These systems are chosen often for curb appeal as main entry doors to residences but may also be used in virtually any other application that calls for a large pivot or French door.

Bifold and Folding Doors

Glass folding doors provide an opportunity to gain open views to the outdoors while maximizing the opening in situations where there is insufficient space for wider swing doors. Folding doors can stack or swing and stack to the interior or exterior.

They can be used along a single-track system and can be constructed of multiple panels with up to 10 panels in one direction. The weight of a folding doors’ panels is carried along the header, which allows for ease of operation, even with large groups of folding panels. Typical folding doors are available in heights varying up to 144 inches and widths up to 42 inches. Most manufacturers do not limit the number of panels that can be designed for a system configuration. Thus, a system of folding doors has the potential to provide an expansive panoramic view of an outdoor space. Folding doors that offer a recessed U-channel track can provide a seamless transition from the interior to exterior spaces that is also compliant with the ADA. To ensure security, designers should look for doors that also utilize completely integrated locking and operation mechanisms.

Glass Folding Doors

Glass folding doors provide an opportunity to gain open views to the outdoors while maximizing the opening in situations where there is insufficient space for wider swing doors. Where there is available space in the design, folding doors can be pocketed into the side and completely hidden from view when open, providing an expansive connection to the outdoors.

Pocketing door systems are very popular, as being able to completely hide the door increases the experience of bringing the outside inside, and it also helps to prevent any damage that could occur to the door system while it is closed, such as from children running into it with their bicycles.

Horizontal Sliding Walls and Operable Glass Wall Systems

Multiple panel door systems that operate along a single recessed channel track system are termed horizontal sliding wall systems, and in the case where they are either framed glass or frameless glass, they are sometimes named operable glass wall system. The tracking system uses multiple panels to span large openings without having to stack the tracks, thus eliminating large jamb widths. Additionally, where there is room, these systems are often pocketed inside a closet, providing a fully open expanse when not closed.

Horizontal sliding wall systems allow the designer to create an “operable wall” system that can span oversized openings, while allowing the panel storage in the open position to be minimal. Configurations include independent panels that all stack together when the system is open. They may also be connected similar to a bifold system, however, the hanging wheel sets are then in the center of the panels to more evenly distribute the weight of the panels. Horizontal sliding wall systems also provide designers with the opportunity for panoramic views to outdoor spaces. Some systems offer panel heights up to 144 inches and widths up to 60 inches per panel without any limits on the number of panels. Some systems can accommodate panel weights in excess of 1,000 pounds.

Combination Lift and Slide Door Systems

Lift and slide door systems incorporate a specially engineered design and hardware set that allows the user to both lift and slide the door system. By using a large leverage handle, the operator engages a double v-gasket seal at the top and bottom of the door to both open and lock the door. The panels in this type of system use their own weight to compress the double v-gasket seals, which creates a completely weather-tight system when in the “down” position. When in the “up” position, the panels, which can weigh 200 pounds or more, can be easily moved with a few pounds of pressure. Track options can include recessed tracks, which come either with or without a drain channel, and the only visible track is a ³/₁₆-inch rail protruding from the finished floor. Thus, the track is “bare-foot friendly”. This system is the perfect design choice for very large openings. The framing is sturdy aluminum construction that allow the large, heavy panels to operate smoothly and securely. Lift and slide door systems are available in a variety of profiles and styles. For example, they can be installed on curved walls and can be designed to disappear into a pocket, thus providing unobstructed panoramic views.

Glass window and door products provide a variety of options in the design of indoor and four-season rooms, allowing designers to transition from inside to outside. The range of materials and panel sizes as well as the variety of available systems provide great flexibility toward creating an interior-exterior interface that capitalizes on views while creating architecturally exciting designs. Outdoor rooms and four-season rooms provide users and property owners with spaces to relax and support mental restoration as well as places to meet others and support social interaction, such as at art museums, restaurants, hotels, and other large public spaces.

Sustainable Wood for Exterior Projects

When considering materials for exterior applications and outdoor environments, wood from the western red cedar has long been revered for its natural durability and beauty. The botanical name for the western red cedar is Thuja plicata. The name is derived from thujaplicin, which is a chemical substance that is found in mature trees and serves as a natural fungicide, thereby preventing the wood from rotting. Hence, its durability lies in its natural resistance to rot, decay, and insects.

Western red cedar is also a sustainable, resilient tree species, as it has one of the widest growth ranges on the West Coast. It grows in lush forests and mountainsides as well as in many forested swamps and stream banks within its range. According to the U. S. Department of Agriculture’s Plant Guide, “western red cedar is one of North America’s great renewable resources. The range of western red cedar is essentially in two segments: a Coast Range-Cascade Range segment from southeastern Alaska to northwestern California and a Rocky Mountain segment from British Columbia and Alberta to Idaho and Montana.”³ Although the species is slow growing, it is naturally durable and has one of the longest life spans of any North American softwood. According to U.S. Forest Service, this species tolerates shade very well and can thus survive in forest understories. In addition, U. S. Forest Service predictions indicate that this species’ growth rates are likely to thrive as accelerated climate change occurs.

Western red cedar also has a broad range of aesthetic qualities, making it a popular choice in design applications. It is pitch and resin free, which means that it accepts and holds a variety of finishes. It provides both color and texture to projects, as it is naturally imbued with rich tonal properties, and the knotty grades of decking and siding add textural enhancements to designs.

Paul Mackie is known as “Mr. Cedar” in the building industry and is an expert in the properties of western red cedar. In his opinion, “Western red cedar is simply one of the world’s most beautiful woods. No man-made material can duplicate western red cedar’s naturally luxurious appearance.”

Environmental Certifications for Western Red Cedar

Climate change and impacts made by development are adversely affecting the environment, and in turn our communities and our health. Design teams can significantly reduce these impacts by specifying products that have been verified for improved environmental life-cycle impacts. Products whose manufacture or harvesting reduce negative environmental impacts can be certified as environmentally friendly. Cedar is third-party-certified environmentally friendly in the way it is harvested and its forests are managed. Over the past 15 years, the green building industry has invested a significant amount of resources to responsible procurement of forest products. The U.S. Green Building Council (USGBC) encourages the use of construction products and materials carrying environmental product declarations (EPDs) that are calculated through a life-cycle assessment (LCA). LCA is included in LEED v4. EPDs contribute to LEED points. They are created according to internationally harmonized standards and are third-party verified, ensuring that the results for the product are valid. Products with third-party certification (Type III), including external verification, are valued as one-half of a point for credit achievement calculation through LEED. According to its website, the USGBC recently developed a new pilot alternative compliance path (ACP) credit for its LEED rating system. The ACP is designed to further advance environmentally responsible forest management and helps to remove the use of illegal wood by promoting responsible wood sourcing and chain of custody.

Cedar in Outdoor Design Applications

Aesthetic considerations and human interaction are not part of the protocols for life-cycle assessments of products, but these qualities are important considerations in design projects. Aesthetic qualities contribute to what people find attractive about a place.

“People who like being outdoors on a deck usually like being part of their natural surroundings,” says Paul Mackie of the Western Red Cedar Lumber Association (WRCLA), articulating the appeal of natural products as compared to the synthetic character of some composites. “If that’s the case, choosing a natural product like cedar is the way to go.”

Cedar is used on a variety of projects from small residences to larger commercial and institutional buildings, and it has been specified as a preferred material on balconies, rooftop decks, and exterior facade cladding. Some examples include the following case studies.

Designing Outdoors with a Rooftop Deck

One of the ways to expand interior spaces into the outdoors is through a rooftop deck. Rooftop decks can provide outdoor rooms for relaxation, entertaining, and dining on both residential and commercial projects. Products used in combination for designing rooftop decks include pedestal systems and modular wood tiles.

The pedestal systems provide the designer with options for creating level decks over sloped surfaces. They can also elevate and support modular wood tiles, pavers, and other surfacing materials over existing surfaces that may be unattractive or that may not be ADA accessible. Pedestals that are manufactured in the United States and made with 20 percent post-industrial recycled materials meet LEED and SITES criteria for recycled content.

Wood tiles that qualify for LEED credits should be commercial grade, constructed from sustainably harvested hardwoods, and available with Forest Stewardship Council (FSC) certified species. Those pedestals and wood tiles that are modular and have interchangeable components provide flexibility with the design composition. Modular systems also provide ease of maintenance, as individual units are easily removed and replaced should any unit become damaged.

Roof Deck Products: Modular Wood Tiles

Modular wood tiles come in a variety of sizes and are fabricated from wood planking. The wood tiles can be fabricated from domestic as well as imported woods. To meet LEED criteria, these woods should be responsibly harvested and FSC certified. Several species of South American (Brazilian) hardwoods, including ipê, cumaru, garapa, and massaranduba, are popular for the fabrication of wood tiles because these woods are so durable. FSC-certified (FSC-C13454) ipê, cumaru, garapa, and massaranduba wood tiles could contribute to LEED points under Materials and Resources Credit 7 (MR Credit 6 for CS). They could also meet SITES Section 5.9 – Support sustainability in materials and manufacturing.

It is important to note that these wood tiles are constructed from premium-grade remnants from the flooring and furniture industries. These remnants are the waste materials and shorts purchased from other industries so the wood planks are repurposed content. Thus, these wood tiles comply with strict regulations regarding extraction, milling, and transport. In addition, it is important that the imported woods used in fabrication of these wood tiles comply with the U.S. Lacey Act and meet the Brazilian Institute of Environment and Renewable Resources (IBAMA) requirements that show proof of origin and legal harvesting.^7,8

Tropical hardwoods are among the preferred woods selected as a source for many modular wood tiles because these tropical hardwoods contain a rich variety of graining and coloration, are exceptionally dense, and are resistant to insects. Modular wood tiles fabricated from tropical hardwoods can be ideal for blending the warm beauty and upscale appearance of real wood with the durability and low maintenance of the tropical hardwood species, thus providing a product that requires minimal maintenance. If maintaining the wood color is desired, wood tiles can be periodically cleaned and sealed. Left to weather naturally, the wood tiles will develop a silvery-gray patina.

Because of their modular characteristic and flexibility, wood tiles can be installed over a variety of surfaces and are adaptable to a variety of sites. Wood tiles can be used to create large roof deck surfaces on top of buildings as well as decks at ground level. Weighing one-fourth as much as 2-inch-thick concrete tiles, wood tiles are a good alternative when surface material weight is a major consideration.

Wood tiles can be laid in a parquet or linear pattern or mixed with other materials, such as pavers, stone, plank decking, or other options, to create unique aesthetics. When used as the sole surface material, modular wood tiles are ADA compliant, as the surface texture and spacing between the units meet ADA criteria. Also, the modular tiles can be removed for routine maintenance, for repairs to the roof, or to gain access to other systems.

The modular wood tiles meet industry standards and certifications for wind uplift, fire ratings, slip resistance, weight-bearing capacity, and seismic. To ensure adequate weight bearing in support of heavier loads, it is recommended that more pedestals be used above the standard 1:2 ratio of pedestals to wood tiles.

Roof Deck Products: Pedestal Systems

Wood deck tiles supported by pedestal systems can be integrated seamlessly to create a rooftop deck that is as simple as it is beautiful. Pedestals have precise integrated spacer tabs that ensure accurate spacing, lock the surface materials in place, and allow water to drain.

Typical pedestal systems have a threaded design, making the leveling process during installation a simple turn of the pedestal base. This allows contractors, designers and installers to accurately plan, precisely align, and uniformly install level decks with a combination of ease, speed, and accuracy. Also pedestals that have a broad footprint provide stability and are usually impervious to freeze thaw cycles.

Pedestals can contain 20 percent post-industrial recycled material and could contribute to Materials and Resources Credits Section 4 as a single product contributing to multiple LEED points. This also meets SITES Section 5.3: Design for adaptability and disassembly, Section 5.5: Use of recycled content materials, and Section 5.9: Support sustainability in materials manufacturing.

Products that enhance outdoor views while meeting safety and sustainability requirements are of benefit to the aesthetics and function of a project, as they can provide the user with a closeup experience of outdoor spaces while ensuring user safety. Railing systems that minimally obscure views are one such product.

Railing Systems to Enhance Exterior Views

Many exterior spaces, such as decks, patios, and roof gardens, require safety rails to meet code and occupancy requirements. Railing systems with glass panel or stainless cable infills framed in an all stainless steel support structure offer options for providing safety while minimally obscuring views. No other commonly used material can match the timeless beauty and durability of a stainless steel railing system. Custom stainless rails enhance the overall beauty of both the indoor and outdoor living spaces, as custom rails can be considered “functional artwork.” Whereas an original painting or sculpture can enhance a living space, custom rails are not only beautiful, but they also provide a functional use within the space. In addition, cable rail, glass rail, and bar rail infills minimize obstruction of the surrounding view, thus allowing greater enjoyment of landscape views and the environment.

Suitability of Stainless Steel Railing Systems for Outdoor Applications

Ornamental rails add beauty to exterior living spaces, and they should be incorporated into the design at the onset to provide a complete project aesthetic. There are a number of railing styles available in the marketplace, including:

• stainless steel cable railing systems,
• stainless steel glass railing systems, and
• stainless steel horizontal bar railing systems.

Stainless steel is well-suited for railing systems because of its chemical composition. Alloys not found in regular steel, such as chromium and nickel, give stainless excellent corrosion resistance. The origin of the name “stainless steel” comes from the fact that it ‘stained less’ than it parent metal.

The two most common grades of stainless steel for applications like railing, sculptures, and facades are 304 and 316. While similar, the amounts of chromium (Cr) and nickel (Ni) vary slightly (8 to 11 percent Cr, 18 to 20 percent Ni for 304; 10 to 14 percent Cr, 16 to 18 percent Ni for 316). The presence of molybdenum in 316 makes it the best choice for more severe conditions, such as marine, pool, and industrial environments.

Prefabrication of Custom-Made Stainless Rails vs. Local Fabrication

When it comes to visual appearance, stainless steel provides a sleek, modern look and can be installed both indoors and outdoors. Creating a beautiful, custom-made stainless steel railing system is not an easy undertaking though, as it requires tungsten inert gas (TIG) welding: a welding skill that requires a fairly high degree of precision and expertise on the part of the metal fabricator. TIG welding is an arc welding process that uses a nonconsumable tungsten electrode to create the weld. In addition, building a custom stainless railing system requires a degree of sophistication and a contractor familiar with the materials. Usually the general contractor subcontracts this work out to a local metal fabricator who estimates, designs, fabricates, and installs the rails. The local metal fabricator will fabricate much of the railing system in its shop, and then, to ensure that everything fits precisely, field adjustments are performed via on-site cutting and welding.

There is an advantage with ‘prefabrication’ in that the railing prefabricator will build out the entire railing system “on paper” first. The prefabricator will adjust all the measurements (down to a ¹/₁₆ of an inch) in CAD, identify and number the system components, and then perform all of the cutting, welding, grinding, and polishing required to build the railing system. When custom rails are prefabricated, the entire railing system ships to the jobsite ready to be installed. Self-installation by the contractor can result in shorter railing installation times and lower installation costs. Additionally, because prefabricated custom rails are built in a quality-controlled environment, the metal fabricator does not have to deal with on-site challenges and other environmental conditions when fabricating the rails.

Stainless Steel Cable Rail Systems

Stainless steel cable railing systems are a good solution when designers are looking for modern and virtually transparent railing systems. These stainless steel cable rail systems provide a linear horizontal aesthetic through the use of thin, highly durable stainless steel cabling. These rails can be used for stairways and to secure outdoor living areas. The railing systems are available in standard 36-inch, 42-inch, and custom heights for residential and commercial use. Local codes will dictate the required heights. There are options to powder coat the rails in a choice of colors should clients prefer something other than the brushed satin (#4 finish, 80 grit) stainless steel finish. Top rail styles are available in various geometric shapes and treatments, including elliptical, flat, round, round with lighting, and wood. Mounting options for the posts include top mount on a deck, stringer or flat surface, fascia mount (on the side), or core drill for concrete installations.

Although there are numerous configurations for the structure of the cable, referred to as “the lay,” the most common lay for cable infill is 1×19. This means that one strand of cable is wrapped by 19 strands of cable. This diameter allows for minimal visual obstruction, and the lay (1×19) minimizes stretch. Although both A304 and A316 stainless are commonly used for cable infill, A316 is recommended, as it provides greater resistance to corrosion. A316 is better suited for coastal environments, areas around pools, and heavily salted roadways.

Electro-polishing the cable will provide an even greater level of corrosion resistance. There are a variety of fitting options available, with both adjustable and nonadjustable components, that will accommodate most cable-anchoring scenarios. In most cases, the cables are tensioned at the ends by tightening a nut onto a threaded fitting. This allows for a clean, sleek line.

Stainless steel cables are very strong and can usually withstand 1,900 pounds of force without breaking. Because of this, it is important not to overtighten the cable runs during installation, as this can damage the posts.

Stainless Steel Glass Infill Railing Systems

Glass infill railing systems provide a clean, refined look for designers requiring a virtually transparent railing system. With glass infill railing systems, there is the added safety and strength of tempered safety glass. The glass infill in these systems can also provide a windbreak benefit. When specifying glass rails, the railing manufacturer typically provides all the stainless steel components, with the glass panels supplied by a glass installer local to the project. As with the cable rail systems, these railing systems are available in standard 36-inch, 42-inch, and custom heights for residential and commercial use.

All railing infill products have strengths and weakness. For example, cable and bar infills tend to perform well in areas subjected to the wear and tear of severe winds, storms, excessive heat, and weather. This is due in part to the fact that their cables and bars are fairly thin, allowing the wind, rain, and snow to easily pass through them. Glass infill, while doing a great job at keeping the line of sight clear, tends to collect dust, dirt, and fingerprints, and it will thus require frequent cleaning.

Bar Rail Systems

Until now, installing bar rails required on-site welding and fabrication. Issues could arise with the quality of the on-site “finishing” of those welds. There is a new system available that is a predesigned and prefabricated component-based bar rail system. As with the other custom railing systems, the component-based bar rails are available in standard as well as custom heights. There are also options to powder coat the railings in a choice of colors other than the brushed satin (#4 80 grit) stainless steel finish, as well as numerous options for top rail styles, post styles, and options for post mounting. Designers can select from the various options to achieve the aesthetic affect and best installation for their project.

Solar-Powered LED Accent Lights for Railings

Solar-powered LED accent lights are an available lighting option for any deck or outdoor living space. These lights are solar-powered and are designed for sustainability and ease of installation. Housed in a stylish yet sturdy marine-grade stainless steel shell, this exterior lighting accessory nicely complements any outdoor railing system by offering sleek, long-lasting elegance at an affordable price.

Created as a lighting accessory for a wide array of exterior settings and both residential/commercial applications, there are a wide range of display possibilities for these LED accent lights. They can be mounted upon deck posts within outdoor living spaces, on second-story rails to create depth, on front walkway pillars to create a welcoming visual effect, or attached to any building’s exterior to accentuate focal points.

This LED accent light is made up of predrilled, A316-grade brushed stainless steel for durability and ease of installation; it also features light channels and an open bottom for a beautiful down-lighting affect. It can provide up to 10 hours of lighting without electrical wiring, as it is powered via one rechargeable AAA NiMH battery. The battery gets recharged during daylight hours via the 1.5-by-3-inch slim solar panel.

This light “is designed to enhance practically any call-out area—outdoor living spaces, grand entryways, second-story railings, you name it,” explains Kevin T. Harris, Director of Sales and Marketing at AGS Stainless. “It is so simple yet elegant, it quite literally lights up any space needing a bit of light.” As this LED accent light is an easily mountable, solar-powered light, it is an ideal energy-saving lighting solution when an electrical supply is neither wanted nor available.

Maintenance Requirements for Stainless Steel Railings

When installed in an outdoor environment, all commonly used railing materials require some ongoing maintenance. This is especially true in high-impact environments near saltwater and/or heavy industry. Although stainless steel is corrosion resistant (particularly A316 stainless), it bears rementioning that this material is known as “stainless” steel, not “stain-free” steel. In many locations, the cleaning routine for an A316 (known also as marine-grade) stainless railing system is a periodic soap and water bath. The railing manufacturer will provide details on the proper care and cleaning of the railing system.

Cable Railings and Code Compliance

Cable railing systems (cable as an infill) are subject to building code requirements. These requirements include minimum loads to be resisted and maximum openings between cables that cannot be exceeded. The load requirement is a 50-pound horizontal force applied on a 12-inch square area. The opening size is governed by a 4-inch sphere not being able to pass between 2 cable rails.

As cable rail is still a relatively new railing solution, not all local building departments have approved its use. The most common argument against using cable rail is that the horizontal orientation of the cable creates a potential safety hazard for young children. The rationale is that the cable can create a potential ‘toe hold” or “ladder effect,” allowing children to climb up on the railings and place themselves at risk of injury.

The use of horizontal stainless steel cables as a railing infill is not prohibited by either the International Building Code (IBC) or the International Residential Code (IRC). Although language to this effect appeared briefly in the code some years ago, it was quickly removed. However, some local building officials are using the older code language as a basis for denying cable rail on projects.

Also, local jurisdictions do have the authority to edit or amend the model versions of the code. This means that, even though the use of cable rail is not restricted by the IBC or the IRC, its use can still be prevented or controlled by more restrictive local building codes. For example, cable rail is specifically banned in Chicago while Oakland allows it, but Oakland has a maximum cable spacing of 2.5 inches on center.

If your local building officials are concerned about the use of cable rail on your project, the railing manufacturer can assist you in working with them. The railing manufacturer should be able to provide you with additional documentation including architectural drawings and engineering calculations for your railing system. Having additional documentation as to the safety and stability of your railing system may help to ease the concerns of your local building officials. If your local building officials still reject it as an infill for your project, you can consider using a railing system with “vertical” cables or bars instead of “horizontal,” or consider spec’ing a system with glass or another panelized infill product like wire mesh panels.

LEED Criteria and Certification

The U.S. Green Building Council’s LEED certification system promotes design and construction practices that enhance the environment, promote sustainability, and benefit user health and well-being. LEED certification is obtained based on a point system and includes many areas related to choice of materials. These include recycled content, potential for product reuse, impact on energy and water consumption, the likelihood of product or coating emissions, impact on indoor air quality, thermal comfort, durability, maintenance requirements, and impact on indoor light.⁹

Stainless steel contributes to LEED certification through its high recycled content and high salvage rate at end of life. In addition, stainless steel has the potential to influence other LEED points based on how it is used in a specific application. Some related points for stainless steel railings include:

• Maintenance requirements: Stainless steel railings are easy to clean and thus require no environmentally hazardous chemicals.
• Indoor air quality and outdoor emissions: Stainless steel is ideal for outdoor applications because of its corrosion resistance. Thus, it requires no protective coating. This eliminates the adverse environmental impacts associated with coatings, such as out gassing volatile organic compounds (VOCs).¹⁰

End Notes

¹“Window Technologies: Low-E Coatings.” Efficient Windows Collaborative. 2000–2017. Web. 23 June 2017. www.efficientwindows.org/lowe.php.According to the publication, “Low-e glass coatings can have an emittance as low as 0.04. Such glazing would emit only 4 percent of the energy possible at its temperature, and thus reflect 96 percent of the incident long-wave, infrared radiation. Window manufacturers’ product information may not list emittance ratings. Rather, the effect of the low-e coating is incorporated into the U-factor for the unit or glazing assembly.”

²A polyamide is a type of plastic having high heat resistance.

³Nesom, Guy. Plant Guide: Western Red Cedar. USDA NRCS National Plant Data Center & the Biota of North America Program. Web. 23 June 2017. plants.usda.gov/plantguide/pdf/cs_thpl.pdf.

^4,5,6The Cedar Book: Volume X, First Edition. Western Red Cedar Lumber Association. 2017. Web. 23 June 2017. www.realcedar.com/wp-content/uploads/2014/05/wrcla-cedar-book-v10-final-web.pdf.

⁷The Lacey Act is a 1900 United States law that bans trafficking in illegal wildlife. In 2008, the act was amended to include plants and plant products, such as timber and paper

⁸IBAMA is the acronym for the Brazilian Institute of the Environment and Renewable Natural Resources, which is the Brazilian Ministry of the Environment’s administrative arm. The IBAMA supports anti-deforestation of the Amazon and implements laws against deforestation where the government ceases to implement.

⁹Houska, Catherine. Sustainable Stainless Steel Architecture. Nickel Development Institute. Web. 23 June 2017. www.nickelinstitute.org/~/media/Files/NickelUseInSociety/Architecture/SustainableStainlessSteelArchitecture.ashx?la=en.

¹⁰Houska, Catherine; P.G., Stone; and Cochrane, David J. Timeless Stainless Architecture. Nickel Development Institute. Oct. 2001. Web. 23 June 2017. www.nickelinstitute.org/~/media/Files/TechnicalLiterature/TimelessStainlessArchitecture_11023_.ashx.

Elena M. Pascarella, RLA, ASLA is a practicing landscape architect, continuing education presenter, and consultant engaged in a private practice based in Rhode Island. The firm’s portfolio can be viewed at www.landscapeelementsllc.com.