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It is easy to understand the allure of attractive metal roofs that often last a half-century or more. Aesthetically, they convey value and even elegance because of their crisp, clean lines.
Metal roofs offer numerous advantages. They are:
- Durable - highest quality metal roof systems offer legendary durability - some copper roofs are still intact on 19th-century buildings. Such roofs offer much of the durability of tile and slate roofs, but often at a lower cost. Generous manufacturer warranties of 30 years or more provide further evidence of their durability.
- Lightweight - Compared to many residential roof alternatives, metal roofs are much lighter. In fact, steel panels may weigh as little as 1/20 the weight of tile or slate. Lightweight roofing reduces the long-term strain on the structure of a building, particularly when snow or ice add weight in the winter.
- Wind-resistant - Interlocking metal roof panels are more resistant to high winds than traditional asphalt shingles and cedar shakes.
- Stylish - The type of metal used in such roofing systems varies greatly from thin-gauge steel to upscale copper. Aluminum, zinc alloy and stainless steel roofing are also available. Metal roofing can be fabricated to mimic the look of cedar shakes, shingles, slate or tile. Since they are among the most fire-resistant roofs available, insurance discounts may apply.
- Environmentally friendly - Metal roofs are also environmentally friendly and energy-efficient. Green building trends favor metal because it is often fabricated from recycled material. At the end of their life cycle, most metal roofs are fully recyclable, which limits the debris going into landfills.
Given their many attributes, it is not surprising that the market share of metal roofs has quadrupled over the past decade.
Common Metal Roof Repairs and Their Cost
Metal roofs last a long time, and often with minimal maintenance. Periodic roof inspections provide timely alerts when repairs are necessary. When the need for a significant repair arises, it is often because of one of the following:
Leaks - Metal roofs are sometimes vulnerable to leaks along seams and where protrusions occur, like skylights and vents. Leaks sometimes develop in the valleys and along the ridges where different planes of the roof meet. For example, end enclosures that are improperly designed may lead to leaks when gutters overflow or ice dams develop. Water also migrates underneath where it meets ridge vents or wall masonry. Early detection of roof leaks may limit cost repair costs to as little as several hundred dollars.
Roof leaks are often due to installation errors:
- The omission of required sealants at roof penetrations and joints
- Failure to install tape sealant under screw heads
- Failure to add an extra sealant strip at the eve connections and where panels meet
- The misapplication or omission of required sealants along longitudinal seams
- Caulking is also essential between any extra trim and the underside of panels
Roof inspectors may use a special super-thin tool that allows them to determine whether sealant was properly applied under the panels at installation. When missing sealant is detected, it is possible that the panel will have to be removed, new sealant applied and the panel reinstalled. This more complicated repair increases labor costs, often calculated at about $40-50 per hour.
Splits, Cracks and Gaps
Damaged panels are repaired by first cleaning the surface and making sure it is completely dry. A 1/2 inch thick layer of appropriate metal adhesive is troweled over the cracked or damaged area. Next, a metal fiber membrane is laid over the area and additional adhesive is troweled over the membrane to create a uniform, repaired surface. Smaller cracks and splits can be repaired with special rubberized tapes, although the surface must still be carefully prepared to promote proper adhesion.
Rust and Corrosion
Sometimes, older metal roofs are subject to surface corrosion which usually appears as pitting. Severely corroded panels need to be removed and replaced. Surface rust must be dealt with, or a more expensive full panel replacement awaits in the future. The affected area should be sanded, scraped or wire-brushed prior to the application of a rust-inhibiting primer coat. A final coat of an approved metal roof compound is then applied.
Storm Damage
Because metal panels are typically well-supported by the substrate, they are usually quite hail-resistant. However, it is still possible for large hail to distort interlocking seams or flashings. When this occurs, it is possible for moisture to get under the panels and to enter the roof's inner structure. Large hail may also decrease wind resistance. Wind damage is more likely if there are missing or poorly-installed roof edge components or missing fasteners. Then, high winds can lift and bend metal panels.
Functional damage caused by hail, high winds or other severe weather is usually covered by a homeowner's insurance policy, less the deductible. Cosmetic damage is either not covered, or the insurer will pay a percentage of the full replacement cost - usually 50 percent of less.
Remedies for Common Metal Roofing Problems
Labor costs are often significantly higher for steeply pitched and/or intricate metal roofs. Short of a full roof replacement, there are remedies for common problems:
- Re-coating the Panels - The lifespan of an aging metal roof is often increased by the application of an approved metal coating, typically at a cost of approximately $1,500 to $2,500. Thorough surface preparation is vital, including the removal of all loose paint, rust, dirt and other contaminants. Contractors typically use grinders, sanders and wire brushes to thoroughly clean the surface. High-pressure water blasting is an alternative when surface damage is not too pronounced. For a manufacturer’s warranty to be valid, the special coating must be applied to an approved thickness.
- Re-sealing - Over time, caulk and sealants may shrink or get hard and brittle, allowing for unwanted moisture penetration. Newer formulations of metal roof caulks better maintain their elasticity. Special rubberized tapes can be used to complete some repairs. For example, EternaBond is a four-inch-wide tape featuring embedded primer and sealant. When properly applied over a clean, dry surface, the rugged micro-sealant compound will eliminate leaks at seams and where cracks or splits appear.
- Fastener Repair and Replacement - A sufficient number of fasteners and the proper use of sealants are critical for long-term moisture resistance. Leaks often occur where fasteners are missing or corroded. The cost of fastener repairs consists primarily of labor expense, often calculated at about $40-60 per hour.
- Sealant Application - An inadequate application of sealant around fastener heads is another common problem. The solution is to caulk all exposed fasteners with a proper long-life sealant.
- New Panels and Components - When entire panels or sections require replacement, costs escalate. Metal roof panels run $2-3 per square foot for thinner gauge steel to $3-5 per square foot for higher grades of steel. Zinc alloys and copper materials are the most expensive of all, at $10-15 per square foot. Partial replacements can easily run into the thousands of dollars.
Metal Roof Maintenance
Periodic pressure washing will maintain the appearance of a roof and flush away contaminants. Although high-quality metal roofs outlast most other types, they still require periodic inspections and maintenance. Some roofing contractors will offer to combine an annual pressure washing with a roof inspection.
Certified roof inspectors look for evidence of:
- Cracks, holes and other damage
- Deteriorating gaskets
- Movement/stress of panels
- Ice and snow damage
- Storm damage
- Compromised surface coatings
- Debris clogging drains and gutters
When a severe storm sweeps through the neighborhood, it is often wise to be proactive by scheduling a roof inspection. If falling branches, large hail or wind-blown debris have compromised seams, metal panels or flashings in any way, it is far better to catch a problem early. If the inspection reveals that there is no damage, the resulting peace-of-mind is more than worth the time and effort.
It is important to ensure that trees and bushes are not rubbing against the roof's surface. Tree and shrub growth can initiate a cycle of constant abrasion that may compromise coatings or damage panels. Impacted panels may require repair, re-coating or replacement.
Full Metal Roof Replacement
When a metal roof nears the end of its life cycle, or earlier installation problems lead to extensive damage, a full roof replacement may be required. Metal panel roofs often cost $9-12 per square foot installed, while metal shingle roofs cost approximately $7-10 per square foot installed.
Property owners that have endured a series of roof repairs over time may find that the band-aid approach is no longer cost-efficient:
- Estimated repair costs to a severely corroded or damaged roof approach the cost a full roof replacement.
- Undetected leaks may cause structural damage that requires major work on the sub-roof.
- Existing roofing must be removed before structural repairs can proceed.
By contrast, a new metal roof will typically come with a lengthy manufacturer's warranty that provides real peace-of-mind.
Concerns over roof leaks and potential structural damage become a thing of the past with a properly installed, new roof. There are some things that will impact the cost of a metal roof replacement:
- Sometimes, metal roofing can be installed right over an existing roof, which may reduce labor costs. Figure on labor costs of approximately $40-60 per hour when structural repairs are necessary before the roof installation can proceed. Materials costs can escalate if timbers, plywood or other components have to be replaced.
- In general, a slightly pitched roof will be replaced in far less time than a steeply pitched one. The intricacy of the roof design is also an important factor.
- Roofs with numerous dormers and other protrusions require added labor. A highly pitched, intricate roof may increase labor expense by a factor of three to five times or more.
Conclusion
Although a metal roof may cost more upfront than many other roof systems, its excellent appearance and long life usually make the investment more than worthwhile. A properly installed metal roof will last for decades. Protect your investment by scheduling periodic inspections. When a problem is detected, a prompt repair is often far less expensive than one that is delayed.
