Is it time to re-roof?

These details can inform your decision to repair or replace.

By David L. Roodvoets

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All roof systems have a finite life and eventually need to be replaced, an expensive project. Roofs need to be replaced when they no longer keep the weather out or are in eminent danger of being blown away by the next breeze.

You might need to use infrared thermography or other moisture-detecting system to find the leak.

– David L. Roodvoets

With good maintenance, most roofs perform well for longer than the manufacturers warrantee. It benefits our communal environment when a roof stays on a building and performs as intended. Keeping the roof in place saves on landfill and the energy embodied in new materials. A well-performing roofing system is therefore the “greenest” roofing system possible.

Facility managers need to be involved with every new roof design or remediation project. Start with the best roofing system for your facility to get the best performance. Although most suppliers will state that their systems can be used on almost any building, there are some considerations that make a big difference. The first is what’s on the roof now.

Figure 1. Most roofs support many air handlers, each of which can be a source of leaks.
Figure 1. Most roofs support many air handlers, each of which can be a source of leaks.

Recent studies have shown that roofs with the fewest penetrations and rooftop equipment require less maintenance and last the longest. However, most facilities use the roof as a platform for much of the building’s air-handling equipment, and that equipment needs to be serviced (Figure 1). Such roofs need to make provisions for heavy and frequent rooftop traffic. Often, pathways of pavers or walk pads connect the equipment to the roof entry. Unfortunately, most designers want rectilinear straight paths parallel to the roof edges to connect the roof entry and the equipment. Most repairmen want to walk the shortest route.

High-traffic roofs are best served by a system that protects the membrane and allows free access for travel. Depending on the loads that might be encountered during maintenance and operation, there are at least three levels of protection to be considered. The most traffic-resistant roof is entirely covered with heavyweight pavers that impose a load of 18 lbs/sq.ft. to 25 lbs/sq.ft. and have concrete compressive strengths of 3,000 psi to 10,000 psi.

Figure 2. Establish and post rules to avoid  initiating roof problems inadvertently.
Figure 2. Establish and post rules to avoid initiating roof problems inadvertently.

Roofs with lots of foot traffic can use lightweight pavers or integrated foam-and-concrete systems. These pavers typically weigh 10 lbs/sq.ft. to 12 lbs/sq.ft. and the integrated systems weigh 4.5 lbs/sq. ft. Finally, there are membrane systems with pavers or walk pads leading to units that will need servicing.

Regardless of the roof system, it’s good to control and record roof access (Figure 2).

The next consideration is roof penetrations. Each roof penetration represents a potential leak. Roofs often have many penetrations to accommodate the activities taking place below. You should group the penetrations into a single stack whenever possible. Heat-weldable membranes such as PVC or TPO generally perform best on roofs with many penetrations.

Build to code

Figure 3. Proper sloping can eliminate ponding.
Figure 3. Proper sloping can eliminate ponding.

Current building codes require that roofs slope 1/4 in./ft. and plumbing codes dictate the required drain sizes. Good roofs have the required slope and drainage (Figure 3). Insulation always is a good investment because it can last as long as the building. Building codes specify the insulation’s R-value. Roofs with inadequate slope to drain can be improved with tapered insulation. Most often the tapered insulation is designed for a roof needing remediation.

Get the right contractors

Although most suppliers compete on the type of membrane or roof covering installed, it’s more important to employ an experienced roofing contractor trained on the membrane and roofing system to be installed. A skilled contractor is the most important factor in getting a long-lasting roof that has few or no problems. Good roof designers and roofing contractors work with the occupants to ensure the roof meets the building’s needs.

Good, bad or indifferent, the roof will need some maintenance. This can be addressed in several ways. The first step is to establish a roof maintenance plan. This can be as simple as setting up a spreadsheet with a checklist, to working with a roofing professional to develop a complete roof asset management plan. Records should include warranties, as-built drawings, modifications, warrantor’s approval letters for modifications and inspection reports. This collection should be stored in an accessible place and remain as part of the building’s permanent documentation.

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