Why We Love and Hate Metal Roofs

Michael O’Bryant Comments
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Let’s face it: The self-storage industry has a love-hate relationship with metal roofs. We love them because metal roofs can usually be built at a lower initial cost. They provide fire resistance, are easy to maintain and, when installed correctly, can provide many years of trouble-free service.

We hate metal roofs that leak. They wear out, or maybe weren’t installed correctly in the first place, and require continual maintenance to keep out water.

Fortunately, there is a solution for owners to rekindle their romance with metal roofs. Retrofitting offers many benefits to satisfy the needs of self-storage operations. But first you must identify and understand the causes of your roofing problems.

Leaking

Leaks are the enemy of metal roofs. To guard against them, know the likely causes:

Expansion and contraction. Expansion and contraction of the metal panels due to temperature change or wind create opportunities for leaks. In through-fastened systems, this movement makes fastener holes become slotted, compromising the seal and water-tightness. In addition, it may cause aged sealants and caulks to fail around stacks and other penetrations.

Roof traffic. Foot traffic on metal roofs can lead to failure of lap seals and may crack light-gauge metal, allowing moisture to enter.

Rust and corrosion. Snow, rain and pounding water combined with rooftop contaminants will eventually lead to rusted, corroded panels. In addition, condensation on the inside of the building mimics a roof leak. If not corrected, condensation can eventually cause failure from the inside out.

Drainage. Ice dams in winter and other debris such as grass, balls and rags can block drains and force moisture through roof seams.

Transitions. Movement between roof sections at valleys, transitions and interior gutters tends to weaken soldered or caulked seams, resulting in moisture infiltration.

Fixes for Leaky Roofs

While metal retrofitting is the right choice for many building owners, numerous factors should be considered before selecting your system:

  • Activity inside the facility 
  • Current system-failure mode 
  • Building-code requirements 
  • Weight and structural limits 
  • Service-life expectations 
  • Chemical-resistance requirements 
  • Budgeting 
  • Selection of the proper roofing contractor

Coatings

Coating systems address surface corrosion and improve the roof’s overall appearance. Reflectivity of a white coating helps reduce thermal-heat gain resulting in lower interior temperatures. If the existing roof is sound with minimal or controllable movement, and loose fasteners can be tightened or replaced, a liquid-applied system can correct leaks at panel laps and fasteners. A variety of coating systems, featuring different properties and prices, is available.

Sprayed polyurethane foam (SPUF) can be applied over an existing metal roof of sufficient gauge, that otherwise meets manufacturer requirements. Since the system is somewhat rigid, a SPUF system doesn’t accommodate movement well but has the distinct advantage of adding R-value. This also virtually eliminates damage from expansion and contraction because metal panels are now insulated from daily temperature changes, a primary cause of movement. It’s not necessary to apply reinforcing fabric over the laps and at fasteners.

During the application of foam and coatings, changes in weather, humidity and temperature can adversely affect installation quality and long-term performance. In some geographic areas, the ideal application window is limited. A trained and trusted contractor is required for proper application.

In some cases, you might consider replacing the roof with a new metal system, an expensive option that disrupts facility activities. A new metal roof also can be installed over an existing low-slope, metal-roof system, but the existing building structure must be sufficient to withstand the added weight. This system can be installed with minimal interruptions to the building’s interior activities and contents.

With a single-ply metal retrofit system, a new roof is installed directly over an existing metal roof. It requires minimal maintenance, reduces energy expenses through increased insulation and can be installed while business operations continue.

Installation

In the installation process, the appropriate insulation (polyisocyanurate, extruded or expanded polystyrene) is cut to fit in the flutes and fitted between the standing seams of the existing metal roof deck.

A cover board or insulation board providing additional R-value is then mechanically fastened over the top to provide a consistent and flat substrate to which the roof membrane will be adhered. In the final step, a single-ply membrane is laid out and fully adhered or mechanically fastened to the existing deck and structure.

If aesthetics are an issue and you like the look of a ribbed metal roof, consider ribbed single-ply systems, which have a similar appearance. Check with a roofing contractor to decide which roofing system is right for you.

Michael O’Bryant is a Western regional manager for D.C. Taylor Co. He has more than 35 years experience in the roofing industry. For more than 50 years, D.C. Taylor Co. has delivered expert roofing, repair and preventive maintenance services nationwide. For more information, call 800.876.6346; e-mail michael.obryant@dctaylorco.com; visit www.dctaylorco.com.


Six Steps to Rooftop Safety

Whenever you hire a contractor to perform work on your property, you take a risk. Make sure your next roofing project is a success by considering the following safety factors before you begin.

1. Culture: Does the contractor just talk about safety, or does he incorporate safety into every part of the work process?

2. Management Commitment: Does your roofing contractor financially support safety programs and enforce safety policies?

3. Training: Are ongoing training programs provided to the contractor’s employees?

4. Risk Analysis Process: Is there a process in place to identify hazards and develop countermeasures to reduce the risk?

5. Proactive vs. Reactive: Does your contractor identify risks or hazards before they happen? Or does he react only after a problem has occurred?

6. Safety Record: What is the contractor’s safety record?

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