With nearly $30 billion spent each year on school construction, according to the American Architectural Foundation, it makes sense to ensure that stakeholders - from students to taxpayers - get high performing schools that create a good learning environment, embody good, sustainable design principles and above all, protect those investments.
Most school designers appreciate how well masonry fills all those roles, if properly detailed and constructed. That means paying attention to some key considerations, including materials selection and methods that impact initial, life cycle and operating costs. Through it all, the top issues are performance and aesthetics.
Let's start on the outside. The exterior building envelope serves as both structure and enclosure.Its major functions are to handle the dead and live loads, while also controlling air leakage, moisture, vapor diffusion and heat transfer.
Moisture is the worst enemy in any wall system. Here are some ways to fight it:
Specify full head and bed joints in the masonry veneer, as the first line of defense.
Pay special attention to where masonry meets a dissimilar material.This can be the brick / mortar interface, or window jambs and heads.Materials with different coefficients of thermal and moisture expansion are natural source for cracks to occur.
Two strategies to evaporate the moisture are draining the water and ventilating the system. Most masonry wall systems or rain screen systems utilize a drainage plane, or cavity behind a veneer.The recommended minimum cavity dimension is 2" for the open space between the back face of the veneer and the face of the insulation.This is for appropriate drainage around any blockages, but also to promote air flow in a cavity system.
Venting and weep holesIf the strategy for the cavity is to promote air flow, the choice of weep vents is critical.Rope wicks will not allow air flow.Open head joints, or open joints filled with a weep vent or mesh type insert will both provide drainage and vent the cavity.Placing weep vents at the bottom of a wall and towards the top of the cavity will promote air flow also.
Controlling air flow is important, too. Up to 40% of energy consumed to heat or cool a building is due to air leakage into and out of buildings.
Think of air barriers as a system, not a single material. Air barriers are specified by performance, and this performance is effective only when all the details are considered.
Take extra care where different components of the building envelope meet.The wall to roof interface needs extra attention since multiple trades are involved.
Try to have a single contractor taking responsibility for as much of the envelope as possible.The coordination issues between separate contractors can be problematic.
Pay special attention to small openings, as huge amounts of air can flow through relatively small openings.
Sustainable Design is more a freight train than a mere trend. As designers seek to maximize their sustainability strategies, masonry materials and systems are valuable assets, with advantages for durability, low maintenance, energy efficiency and good indoor air quality.
Perhaps the greatest benefits come from looking beyond simple material selection to overall outcomes. Cost-effective design measures start by looking at the building envelope, particularly when it comes to the U.S. Green Building Council's (USGBC's) Leadership in Energy and Environmental Design (LEED). For the building envelope, green building performance is based on five concepts: thermal resistance, thermal mass, air infiltration and exfiltration, moisture penetration, and sustainable details. Systems include mass materials (e.g. brick, block, stone, tile, and terrazzo), insulation, air barriers, vapor barriers, and flashing and weep materials, with each system uniquely contributing to one of the five building performance concepts.
Performance and Good Looks
Designers continue to explore masonry for its versatility, durability, and yes, fun.Those are all important considerations for budget-conscious school projects. "We find ways to make it work," says Bruce Wujcik, Senior Architect at Svigals + Partners Architects in New Haven, CT. "We look to do modern design and have more visual impact. It makes it easier to sell to the owner. They're more surprised sometimes with what we came up with."
That was certainly the case for the award-winning John S. Martinez Elementary School, where "sails" and "flags" were created by clever use of angled and curved walls, diagonal expression of joint pattern, and Norman brick with three-course running bond. "We went to masonry for the durability" but got a lot more, says Wujcik.
For their Columbus Family Academy, they drew inspiration from modernism pioneer Alvar Aalto, using different brick sizes and shapes, distinctive bonds and walls moving in and out of plane to make light and shadow an integral part of the design.
For Bryant University's new Interfaith Center, Gwathmey Siegel & Associates gave traditional masonry materials like brick and stone the most modern of looks, thanks to innovative applications that included a rain screen wall system and reinforced lightweight limestone panels, which joined wide sweeping arches, radial walls and brick veneer to create a dramatic statement.
There are a lot of ways to use traditional materials in contemporary design.The flexibility of unit masonry construction and stone or composite panels makes it compatible with innovative design -- as long as everyone on the project team, from designer to installer, knows what he or she is doing.
Not all installers are created equal.Be sure to specify appropriate skills and upgrade programs in the building envelope and its functions.
Sample panels showing all the components of a building envelope are always a good idea.Designer expectations for color, texture and the level of workmanship are agreed on before work begins, and all parties have a physical reference during the job.Panels should either be a part of the structure or stay on the job site.
Working closely with the contractor is critical to achieve high performance by ensuring that all parties have the same understandings. The mason contractor should attend pre-job meetings.For the Bryant University project, contractor Grande Masonry also relied on IMI details that helped to reduce thermal transfer and project costs, in part because they were able to take the lead on the entire exterior envelope.
It's all in the details.At the end of the day, a school has to be durable, multi-functional, flexible and cost effective... and again, look good doing it.The many individual materials that make up a functioning building envelope need great care in design and construction.
The International Masonry Institute has many tools to help designers achieve the best performing school buildings, including the Masonry Detailing Series (http://imiweb.org/design_tools/masonry_details/index.php), Sustainable Solutions (http://imiweb.org/design_tools/sustainable_masonry/index.php), the LEED Checklist for Masonry, and educational opportunities (http://imiweb.org/education/index.php). IMI offers free consultation for plan review, material and system selection. Call 1-800-IMI-0988 or go to www.imiweb.org.
David Sovinski is IMI National Director of Industry Development. IMI represents an alliance between the International Union of Bricklayers and Allied Craftworkers (BAC) and union masonry contractors. His experience includes masonry project manager, estimator, and architecture and technology teacher at Indiana University Purdue University, Indianapolis.
PHOTO CREDITS
John S. Martinez Elementary School - Woodruff/Brown Architectural Photography, courtesy of Svigals + Partners Architects
Christopher Columbus Academy - Robert Benson, courtesy of Svigals + Partners Architects
Bryant University Interfaith Center - IMI
