Accessibility

Ease of access to the plenum throughout the service life of a ceiling is a priority for building owners and facility maintenance managers, particularly as the equipment overhead is becoming increasingly complex. In addition to the routine cleaning and servicing of many separate systems, such as lighting fixtures, ductwork, plumbing, air diffusers, and fire protection, there are new demands requiring easy accessibility; for example, the need to install wireless access points, or change out old for new generations of cable or lighting technology.

Suspended ceilings with flat panels either completely or partially concealing the space above, with “hook-on” installation providing removal of panels for full downward accessibility, are among the easiest to install and most economical wood ceiling types. More complex wood ceilings can also be designed for efficient access, including custom flat, radial, curved, and torsion spring ceilings. Accessibility is another area where manufacturers have developed complete, preengineered installation systems, featuring the same range of options discussed throughout the course, in visual effects and performance.

Tested systems and careful attention to details will avoid common problems with some accessible ceilings, such as surface scratching, corner damage, and most important, potential physical injury to the worker.

To design an accessible wood ceiling that works safely and efficiently and provides all the other benefits of wood ceilings, there are a number of important basic questions to consider in the early stages of design:

• What is the anticipated frequency and type of access needed?
• What is the overall weight of the ceiling? Veneered wood panels can weigh up to 3 pounds per square foot. Heavy panels will require special design to make sure they can be removed safely.
• Is there a need for a special tool for downward accessibility?
• Will the accessible ceiling comply with all other relevant codes? For example, the overall system may need to be tested in accordance with IBC for use in your seismic category. The type of access permitted can also be a factor in fire ratings.
• How will trim (e.g., upturns or perimeter trim) be used to hide suspension elements?
• Where ceilings are continuous with walls, how will veneer be coordinated?
• Does the manufacturer have a program in place to train facility and building managers on removal or replacement of panels?

The Botanical Research Institute shown in Figure 4 is an excellent example of many aspects of wood ceiling design, including a high level of sustainability as discussed below. In addition, it uses a new preengineered integrated system to provide plenum access, streamline installation, and deliver its performance attributes and design appeal. In fact, accessibility was an important part of the building’s sustainable design. The building uses a geothermal HVAC system, so no large air-handling units are needed. Instead, numerous air handlers much smaller in size are installed above the ceiling. The preengineered wood ceiling system included patented hook-on panels to provide maintenance crews safe, efficient access to the units.

Moisture and Humidity Resistance

All wood panels are hygroscopic, meaning they respond to changing humidity levels by expanding or contracting. This natural response is accounted for in all furniture design and construction, and should be considered in the effective design of wood used in walls or ceilings.

According to the U.S. version of the North American Architectural Woodwork Standards (NAAWS) 3.0 published by the Woodwork Institute: “The space in which architectural woodwork is to be installed needs to be engineered with appropriate humidity controls to maintain its optimum relative humidity.” Virtually all wood ceiling and wall manufacturers have the same requirements to ensure this. The conditions to be maintained are in a range achievable with normal HVAC in operation:

• Temperature: 50 to 86 degrees Fahrenheit (10 to 30 degrees Celsius)
• Relative humidity: 25 to 55 percent

Proper manufacturing of wood panels is important to this aspect of performance as with almost every other, and thus has a direct effect on the ceiling’s long-term durability. For example, dimensional stability in a veneered panel is achieved by matching the species of the face veneer and back veneer. This is similar to a bar joist: the strength is in the top and bottom chord. If the veneer species on the face and back do not match, they will react differently to humidity, and this can cause warping of the panel.

Sustainable Spaces

Solid wood and bamboo veneer are inherently sustainable materials, made from renewable resources, and with documented low-life cycle costs and a low carbon footprint. The ability to reclaim and repurpose wood materials is another factor in its positive environmental impact profile.

The Botanical Research Institute shown in Figure 4 illustrates how wood materials are used to express a deep commitment to environmental excellence through inventive design and carefully selected products. For example, several types of wood and plant-based materials, including rapidly renewable, FSC-certified bamboo, were chosen for the LEED-NC Platinum project for both environmental and aesthetic reasons.

In the Lawrence University-Richard and Margot Warch Campus Center (Figure 9), FSC-certified wood in the ceiling systems contributed to a LEED-NC 2009 Materials & Resources Credit 7.0 (Certified Wood). The facility was awarded LEED-NC Gold, the first higher-education building in Wisconsin to achieve this level of recognition.

The wood industry has focused intensely in recent years in improving, measuring, and documenting the outdoor and indoor environmental performance of wood products. Some of the important certifications and guidelines to be aware of when comparing the sustainability of wood ceiling and wall products include:

Forest Stewardship Council (FSC) Certification: This ensures that products come from responsibly managed forests. Independent certifiers with third-party verification assess forest management and chain of custody using FSC standards.

Rainforest Alliance: This is a founding member of the FSC and a third-party certifier of wood products sourced from forests managed to protect endangered species, forest areas with high conservation value, and their workers and communities. Look for the Rainforest Alliance Certified seal to ensure compliance.

U.S. Department of Agriculture BioPreferred: This program works to assist development of markets for biobased products derived from plants and other renewable agricultural, marine, and forestry sources. More than 2,500 products in 100 different product categories have been certified to date. Products that are part of the BioPreferred program are listed on the USDA website. Look for biologically based, rapidly renewable, and high recycled content in acoustic fleece, backing, and panels, and solvent-free lacquers for surface finishes.

California Air Resources Board (CARB): This maintains a comprehensive production standard for formaldehyde emissions from composite wood panels. CARB Phase 2 certifies compliance with stringent formaldehyde emission levels that particleboard panels, MDF panels, and hardwood plywood panels must meet.

Environmental product declarations: An EPD for a specific product is a standardized, internationally recognized, independently verified, and comprehensive way of identifying the product’s full environmental impact, including many aspects of life-cycle cost, energy use, environmental impact, and global warming potential, from material extraction to end-of-service recycling or disposal.

LEED: Because of the variety of natural substrate and veneer materials available and the relative cost of these systems, they can make a significant contribution to LEED credits. (Note that wood veneers applied to metal panels do not deliver the same credits because the value of the veneer is well under 10 percent of the overall panel cost and represents less than the 70 percent of the panel’s composition required by LEED).

Although specific products and projects will vary greatly, in general, veneered wood panels contribute in these ways:

LEED 2009

• Recycled Content (MRc4)
• Regional Materials, dependent on project location (MRc5)
• Rapidly Renewable Materials (MRc6)
• Certified Wood (MRc7)
• Low Emitting Materials – Composite Wood (EQc4.4)

LEEDv4

• Regional Materials, dependent on project location (MR credits)
• Building Life Cycle Reduction, Interiors Life Cycle Impact Reduction (MRc BD&C, MRc ID&C)
• Building Disclosure and Optimization – EPD (MRc BD&C, MRc ID&C)