Retrofit Roofing for Standing Seam Metal Roof Systems

There are basically two types of standing seam metal roofing systems for commercial facilities.

Architectural systems are intended to be visible from ground level, providing an attractive look that complements the building’s appearance. Structural standing seam metal roofing systems are intended to be more functional than aesthetic and are common on low slope buildings where the rooftop is not visible from the ground.

Metal roofing is practical and economical to install at the time of construction, provides reliable weather protection, and if properly installed will provide excellent service for many years. Billions of square feet are in place, with an estimated two billion more installed every year.

Metal Roof Issues

Although structural standing seam metal roofs perform well for many years they eventually deteriorate, and leaking will develop. Left untended, leaking metal roofs may damage building contents and pose a risk to occupants, but could cause structural damage as well. Spring is a good time to inspect roof systems, when snow and ice are melting off and exposing problems that may have developed during harsh weather conditions.

Here are some issues experienced by all metal roofing systems whether structural, corrugated, low or steep slope:

Thermal Forces

Perhaps the most significant cause of damage to metal roofing is the constant movement due to changes in temperature both daily and from season to season. The constant expansion and contraction inherent to metal causes seams to open and cracks to develop at fasteners, penetrations or at changes in plane at a parapet or peak.

Because standing seam roofs are made of rigid metal sheets fastened together, thermal forces inevitably begin to wear and damage a metal roof over the course of time.

Corrosion

The long-term effect of moisture on metal is well known. Water in the form of dew or precipitation combined with chemicals from air pollution or from industrial or manufacturing operations cause corrosion or rust that eventually develop into perforations. Damage to metal roof finishes from hail, roof top traffic or rooftop work can also contribute to rusting or perforations.

Interior Condensation

Cold outside temperatures can cause moisture to form on the underside of metal roofs that are not properly insulated. This could be due to insufficient insulation, gaps between insulation runs or insulation damage. Warm interior air carrying moisture vapor rises and collects as water or frost on the bottom of metal roofing panels.

This condensation can cause drips, even when the outside weather is dry. Real problems develop when the metal oxidizes, and rust forms on the roof deck interior or other exposed metal interior structures.

Addressing Metal Roof Problems

There are numerous possibilities for repairing or reroofing a metal roof system, some highly effective, others classified as short term or repairs.

Sealing and Coating

This is an economical method that seals seams and adds a waterproof coating. But it is only a temporary fix, because weather variations will continue to affect the roof deck. The metal will continue to expand and contract, and the new seals and coating will split at seams or flashing points where metal movement continues.

Coatings are often demonstrated to show elasticity. Initially they perform well but fail due to constant flexing and stress.

Spray-on Foam with Coating

With this relatively low-cost option, the metal roof is sprayed with urethane foam and then has a coating applied to protect the foam. This approach helps protect against precipitation and interior drips, but foam coatings typically are irregular on the surface when applied and collect water.

The downside to foam roofing is the difficulty in removing it down the road should it become saturated.

Replacement with a New Metal Roof

This may seem the most logical solution, given the existing roof served well. Replacing the metal roof with new metal is costly and can disrupt normal building operations.

Metal replacement will require the building to be open to the outdoor environment during the job, allowing weather, contaminants, and wind into the operating facility, putting operations, contents, and staff at risk.

The Best Choice: PVC Retrofit Roofing

We believe there is a better alternative. Aging structural standing seam roofs are excellent candidates for a single-ply PVC metal retrofit solution, professionally installed by our courteous and competent crewmen.

A Sentry membrane retrofit installation on your metal roofed commercial facility is simple and non-disruptive. We will install insulation between the metal ribs to create a level surface, then overlay with another layer of insulation to provide a uniform, flat surface.

The new PVC membrane is rolled out over the insulation and mechanically attached to building structure or the metal roofing, depending on the exact type of metal system. Vents, stacks and other penetrations are made watertight with custom made prefabricated flashings, the same material as the deck membrane.

We measure every detail on your rooftop and flashings are manufactured to fit by Duro-Last, in-house under ideal factory conditions, saving rooftop labor. The installation will be backed by up to a 30-year manufacturer warranty, depending on the re-roofing options selected.

Benefits of a PVC Retrofit Solution

• It will be installed over your existing metal roof, without an expensive tear-off.
• Insulation will be added, improving building energy efficiency.
• The Duro-Last membrane is highly reflective, also adding to energy efficiency and will help keep the building cooler on hot, sunny days.
• Added insulation can help eliminate moisture condensation on the interior of the metal roof.
• The membrane system is not affected by expansion and contraction in the metal roof, providing an excellent service life.
• Avoid the failures common to coatings or sprayed foam roofing.
• Less expensive and disruptive than replacing the roof with a new standing seam roof.

Sentry Roofing is one of Duro-Last’s most experienced authorized contractors, with 35 years’ experience installing Duro-Last and successful installations in 40 states.

Whatever your commercial roofing need, we would welcome the opportunity to inspect the existing roof system and offer a high-quality, cost effective and long-lasting solution. Let us know how we may be of service!