Keeping the Lid On
Jun 1, 1999 12:00 PM, Stephen R. Mulvihill
When the topic of school roofing is discussed, administrators often make the same three statements to architects and roofing specialists:
-"We want a roof that lasts the longest possible time." Unfortunately, a "but" usually follows this statement, as in "...but we don't want to spend much money." In reality, saving money on a new or replacement roof ultimately can generate the most expensive maintenance item in the budget.
-"Give me a roof that won't leak." The reality is that all roofs leak at some time. And water that appears to be coming from the roof can actually be a wall or window leak.
-"I like a roof that's easy to patch." This is poor logic. A well-designed and installed roof should require minimum repairs.
To resolve roofing concerns and save money, it is wise to learn the basics of roof design, maintenance and purchasing. Five-year plans and budgets for roof acquisitions and management also should be developed.
Design considerations In architectural design, the roof is an integral part of the building's plan and requires the expert skills of a professional that specializes in roofing. In new school construction, the roof may account for only 7 percent of the budget, but an improper design or poor installation can add up to years of major expense.
Replacement decisions are impacted by:
-The school's structure, walls and windows, mechanical systems and interior-space usage.
-Roofing market conditions.
-Contractor availability.
-The school's past roofing history. The geometric footprint of the roof should be simple, avoiding complex areas and compound valleys. A flat roof often is more appropriate for a complex building shape, but there are many things to consider when deciding between flat and steep roofs. Schools often change, adding or removing roof equipment; a flat membrane roof is easier to adapt to changes, while a steep roof is not flexible. A flat roof costs less initially and can be repaired easier; however, a properly designed steep roof will have a longer life.
If administrators prefer a steep roof, they should be aware that steep roofs have a significantly higher first cost and require underdeck ventilation. Avoid installing large, roof-mounted equipment on any roof, but especially on a steep roof.
Do not accept roof details with horizontal surfaces. In the roof's field area, all surfaces must drain at least 1/4-inch per foot and 2 inches per foot on the edges. Interior roof drains tied to a proper storm-sewer system always keep the roof draining in cold weather.
Do not necessarily apply the same roof to all the schools in a district, since each school requires an individually planned roof system. In selecting a roof, consider the following criteria:
-Intended longevity.
-Flexibility for installing new equipment.
-Need for an effective vapor retardant.
-Amount of potential damage from roof traffic.
-Availability of experienced local contractors.
Long-term plans As long-term propertyholders, schools need five-year maintenance, repair and replacement roof programs to manage roof systems with long life cycles. For example, if properly maintained, even a traditional, flat membrane roof can give 30 years of performance. The five-year plan should be reviewed annually, and adequate funds should be budgeted consistently. To develop a five-year plan:
-Inventory all roofs. For each roof area, develop a measured CAD drawing and locate the equipment; identify and tag each area; and document the construction and repair history. Record warranties and the names of contractors who know how the roof was installed.
-Assess the condition of roofs. Obtain an independent, professional opinion of the current condition and projected remaining life of each area. Hire a professional roof consultant to conduct nondestructive moisture tests using nuclear, infrared and capacitance techniques, supplemented with "test cuts."
-Inspect building condition. This includes each building's contiguous walls and windows, curtainwalls and roof-mounted HVAC equipment, because many leaks are from these sources and not from the roof.
-Estimate appropriate repair for each roof area. Should the roof be replaced? If so, when should it be replaced? What will the cost be? Does it require a capital investment to prolong its life for 10 years? Or should it be replaced within five years, inputting no major investment and letting it survive on limited repairs? Perform the same analysis on contiguous walls and windows.
Under the five-year plan, bring roofs and walls up to a maintainable standard. Realize that school roofs suffer continual abuse from workers and roof traffic. Install permanent metal ladders to all roofs so they are accessible for maintenance. Do not use in-house personnel for repairs unless the employees are experienced with sophisticated institutional-roofing techniques.
Exercising caution If a replacement roof is necessary, investigate exactly why the existing roof needs to be replaced. Identify the underlying causes of prevailing leaks, and correct those particular problems in the new roof, such as installing needed expansion joints. Repair or replace leaking contiguous walls and windows. Keep in mind that roof-mounted HVAC ductwork is a constant source of internal water damage.
It also is important to understand which materials and installation techniques work best under the weather conditions prevalent in your part of the United States. For example, in the southwest, the main issues are energy conservation and high UV levels. In the southeast, energy conservation, high humidity and wind resistance are important factors. High winds, moderate UV levels, snow and ice impact roofs in the northeast United States. Midwestern roofs face moderate UV conditions, extreme snow and ice, and hail storms.
Do:
-Choose a simple roof design.
-Make decisions from a five-year plan.
-Use proven roofing systems and materials.
-Select a tough, walkable surface.
-Accept "roof failure"-the need to replace a roof.
-Hire an objective, experienced roofing consultant.
-Check roofing contractors' references.
-Understand important roofing concepts.
-Consider residual life beyond the guarantee.
-Know what you are buying.
-Have all contractors bid on the same design and system.
-Expect eventual building leaks.
-Budget enough funds to meet projected expenses and "worst-case" situations.
-Maintain and plan to reduce the impact of roof leaks.
Don't:
-Make decisions based solely on design trends.
-Buy odd or unique roof systems.
-Purchase a roof based on guarantees alone.
-Succumb to sales gimmicks and vested-interest advice.
-Install large equipment on steep roofs.
-Apply one roof system to all buildings.
-Believe that replacing a roof will stop all leaks.
-Expect a recovered roof to have the same life span as a new roof.
Oak Lawn High School, a large suburban school in Illinois, has 42 separate roofs. At one time, the school had 12 different systems ranging from single-ply to traditional built-up roofs.
The challenge was organizing a logical roofing-management program for 42 roofs needing either preventive maintenance, a capital investment for major repairs, or replacement. Another problem was identifying all of the school's non-roof leaks, such as wall and window leaks.
Each of the 42 roofs required an individual design solution. The architect/roofing consultant analyzed the roofs and catalogued problems, identified the separate roof's current status, and developed specific solutions to develop a multi-phased repair and replacement plan.
In-house staff should perform the following maintenance tasks on a regular basis:
-Keep roofs clean.
-Remove all debris, leaves, balls and other items that can clog drains and gutters.
-Keep the roof draining-"free up" roof drains whenever necessary.
-Avoid chopping ice and digging snow off the roof, unless it is an emergency, because roofs are easily damaged by well-intentioned snow removal.
-Ensure that HVAC workers do not leave trash or drop corrosive materials on the roof.
-Thoroughly inspect the roofs at least twice a year, and have a trained roofing professional inspect them annually.
