Waterproofing and Insulation

• By Ellen Kollie
• 02/01/08

Waterproofing and insulation affect a building from the roof down to the foundation. In between the roof and foundation are walls, windows, doors, and joints.

It’s especially critical for schools to have high-quality waterproofing and insulation because they’re designed to perform for a long period of time. In addition, many schools today also serve as community centers, offering such amenities as adult education and recreational facilities after school hours, so high use demands high quality.

Naturally, keeping a school dry goes hand-in-hand with the facility’s long-term performance, as most building materials either degrade or don’t perform well once exposed to water or water vapor. Compounding the situation is that failure often occurs in areas where it isn’t recognized until it’s well advanced, like a leak in the roof seeping so deep that a ceiling shows a water stain or even drips.

“It’s a constant challenge for architects and engineers to keep buildings waterproof and insulated,” says Will Kaly, project manager for Dayton, OH-based Lorenz Williams, Inc.

In the Beginning

The best time to make sure a school is waterproof and well insulated is during planning for new construction. “It has to start very early in the process,” insists Kaly, “all the way out to the analysis of the building location itself.”

Consider the climate — is it wet or cold? Will it be a long and narrow facility with southern exposure from the sun? Will it be hit with strong winds from one direction? “These considerations may not seem very obvious,” Kaly points out, “but they have a very large impact on the overall building systems.”

Similarly, the interior has to be considered during planning. “What are the uses of the interior spaces, and what do you require of them?” asks Kaly. For example, a natatorium is a different design challenge than a library, yet you want to keep water out of each.

Finally, give thought to the systems you’re considering installing relative to the interior aesthetic, finishes, and budget, as they also lend themselves to one strategy or another for keeping water out.

Undoubtedly, it’s more challenging to improve a school’s water seal and insulation once it’s occupied. “In new construction, you’ve got the ability to install appropriate systems with little delays and according to use,” Kaly points out. “It’s more of a challenge when you have maintenance and repairs and you’re trying to keep the facility operational.”

For example, a leak can be a real challenge to diagnose because it’s rarely easy to access a wall cavity or the underside of a roof. Is the water coming from a failed joint? A flashing detail? Maybe it’s even a broken waterpipe in the plenum above the ceiling.

Sustainability Is Here to Stay

Ensuring schools are waterproof and insulated comes with a bonus — contributing to sustainability. One reason is that they require less repair and maintenance, so there are less materials going to landfills. Another is that such facilities use less energy. “Buildings result in 48 percent of greenhouse emissions and use up to 75 percent of energy generated at power plants,” says Kaly. “They have a large impact on the environment, so reducing energy consumption is important.”

The general public is behind school districts in moving toward sustainability. Anything administrators can do to improve a facility’s sustainability wins public support and kudos. “We see the designers, owners, and end users coming to the table and working collaboratively toward sustainability,” Kaly notes. “That’s a good thing.”

Weatherizing Your Facilities

When it comes to providing for your building envelope, attention must be paid to some specific areas, and high-quality products must be chosen.

Roofing: Roofing insulation can be either on top of or beneath the roofing membrane. Which is chosen will depend on what you’re comfortable with, the region in which the facility is built, and what the contractor is comfortable with.

Insulation is often installed on top of the popular single-ply membrane-type roofing system. If a leak occurs in this type system, it’s relatively easy to locate.

Insulation can also be on the bottom of the inverted roof membrane system. “I feel it’s a better system,” says Monica Armstrong, project manager for Atlanta-based The Facility Group. The drawback to this system is that leaks may be more difficult to find.

One insulation option is polyisocyanurate, used in both new construction and renovation, and adaptable with a variety of roof systems. The high-thermal, closed-cell foam plastic insulation is available in a range of sizes and offers a high thermal value per inch.

“Because polyisocyanurate is closed cell, it has attributes that other insulation materials don’t have,” says Jim Whitton, national sales manager for Portland, ME-based Hunter Panels, which manufactures polyisocyanurate roof insulation panels. As a result, the product qualifies for LEED certification credits.

Finally, when it comes to roofing, it’s critical to prevent ponding water at penetrations where items are mounted to the roof. An excellent method is to use a curb that’s at least a foot high and that runs up the side and over the top of the mounted item.

Windows: Windows are a penetration in a building’s exterior, so it’s critical to seal the joint between the window system and wall system. “Don’t depend just on caulking or sealants to provide that barrier,” says Bob Gunning, AIA, project architect with The Facility Group. “Use a flashing.”

Skylights: If you’re installing skylights, do your research to make sure you choose a system that’s tested to withstand wind pressure and the elements. Seal it with flashing and caulk. And, because it’s a roof penetration, be sure it has a curb that’s high enough to keep ponding water from getting into the joint.

Doors: Doors can be protected from inclement weather with weatherstripping, which doesn’t reduce energy costs so much as it increases comfort. Fortunately, it’s inexpensive and quick to install. Gunning advises using a compressible weatherstripping around the door frame to create a tight seal. Combine this with a sturdy sweep attached to the bottom of the door itself and/or threshold weatherstripping.

In older facilities, consider replacing the factory-installed weatherstripping that’s pressed into channels in wood door frames and slipped into channels on aluminum door frames.

Also, consider installing steel doors, which are well known for their ability to keep out poor weather. In addition, they’re long lasting and recyclable.

Building exteriors: Water repellents applied to a building’s exterior substrate to create long-lasting protection from the negative effects of weather are becoming more popular. They can be applied to either existing or new construction, and they work to reduce damage caused by rain, frost, and pollutants, thus decreasing maintenance costs.

Water repellents can be applied to a variety of surfaces — brick, concrete, natural stone, sand limestone, split face block, and stucco/plaster.

Below-grade drainage: A sure-fire way to keep a building waterproof is to keep below-grade water away from the foundation. A drainage system must be well thought out during new facility planning. When done correctly, it prevents leaky basements and structural damage.

“A drainage product, while not contributing to the creation of a pretty facility,” notes Jason Covington, general manager of Wylie, TX-based CCW’s Waterproofing Division, which manufactures a drainage system, “lends itself well to the green movement in that it increases a building’s lifespan.”

Above-grade waterproofing: Both air and vapor barriers are above-grade waterproofing products designed for new construction. When properly designed and installed, they seal a building from air and moisture.

Specifically, a vapor barrier prevents moisture from entering the cold portions of a building’s envelope, thus reducing the potential for condensation, which causes both mold and building deterioration. An air barrier stops mass airflow into and out of exterior walls, thus preventing water vapor from entering the building envelope.

Barriers are made in a variety of materials and come with a variety of applications. For example, Some are a spray-on, rubberized asphalt emulsion that creates a monolithic membrane around a cavity wall’s exterior, providing either a polyethylene or plastic barrier. When sealing a building with either a vapor or air barrier, be sure to seal joints between materials, as well as windows, doors and corners.

Exterior wall systems: There is much to choose from in today’s exterior wall systems. Manufacturers have developed systems that offer low maintenance, energy efficiency, and durability. For example, precast wall systems offer a wide range of cladding materials, such as EIFS, brick, metal, and granite, and are delivered to the job site for immediate installation.

Another example is an insulated concrete form offering energy efficiency and construction speed. These systems feature concrete that is sandwiched between EPS foam and usually come  in 8-ft.-long by 18-in.-high sections. When choosing an exterior wall system, compare initial cost vs. maintenance cost vs. energy savings of several systems to find the best fit.

Words of Wisdom

Naturally, choosing the right building products is important to constructing waterproof and well-insulated schools. But the experts all agree that there’s more to the equation.

For one thing, getting involved early in the design process and communicating well during that process, ensures success. “During design, let’s re-evaluate some of the products we’re putting in or on our facilities,” says Whitton. “Ask questions, like why did we pick that tile? Why are we leaving the gym roof exposed?”

Also, be sure to look at long-term costs as opposed to just construction costs. Covington notes that the cost of oil is only going to continue to rise, so administrators have to consider products that reduce a facility’s overall energy consumption now and in the future.

Whitton agrees, pointing out that the money spent upfront on a higher R-value is soon recouped through long-term energy savings.

Finally, the experts say, once the facility is built, maintain it. “Administrators probably hear that all the time,” says McGettigan. “And, while most educational facilities are made of sound building materials like brick, they still require maintenance.”