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Advantages and Disadvantages of Metal Roofing

This morning, a prospective client phoned to request the replacement of her metal roof.

“Replace the metal roof?” I queried. “Yes” the customer replied. She went on to explain that she had purchased the house a year earlier, and was told by the previous owner, that they had replaced the roof with new metal shingles, and that the roof had a 50year, limited lifetime transferrable warranty.

She further commented that the roof leaked near the chimney, and she suspected at the area of one of the house dormers. I asked if she had attempted to contact the original installer. The senior couple that had sold her the home could not recall the company who installed the roof, and they had no reference as to the type of metal shingles that were installed. She had been directed to several “metal” roofing companies, had searched metal roofing websites on line; but none could identify the materials, and were reluctant to try to repair the job.

This was in great part as a result of not being able to source materials. Ball park estimates to repair her job, even if the product manufacturer could be identified, was in the range of $6-10,000, depending on whom she spoke with.

After considerable time and effort to try and resolve the matter; she finally had given up and requested that the roof simply be removed, and that she wanted it replaced with more conventional shingles.

There are a few take aways from this story. The first being that when replacing one’s roof; it is prudent to keep records of who the installer is, and any applicable product and warranty information.

The second take away is to beware of the so-called life time warranty claims made by many manufacturers these days. While most do honour their warranty claims, certain metal roofing manufacturers and installers that have started up in the last twenty years, have failed to remain in business, also for a variety of reasons.

To be clear; metal roofing is a good choice, and has been used for hundreds of years as a water shedding material. The key to a good metal roofing system is selecting the right products suited to the application, and selecting a qualified contractor who is experienced in the installation methods.

The first step when considering a metal roof system, is to understand the details of the structure it will be installed on.

As an example; condensation can be a consideration, if the roof is being installed over an under- insulated attic, or an attic which may have heat loss issues. Under some circumstances a cold roof assembly may have to be specified.

An un-heated garage or barn, would be far less complex, because the exterior and interior temperatures in winter may be fairly similar. It is therefore wise to enlist an engineer that can identify any design requirements, and who may be able to provide specifications for the particular building circumstance.

This further serves to protect the building owner and the installation contractor, because the engineer is providing the solution.

Also to consider are the many types of metal roofing products that are available in the market place.
In broad terms, there are a few common types of metal roofing products that fall into some basic categories.

Architectural Metal Roofing, is often manufactured using copper, leaded copper, zinc ,or stainless steel.
Such roofing is typically hand crafted by artisan copper smiths that possess the skills to custom fabricate panel roof systems involved standing seams, soldering, and roll forming the chosen materials.

Such metal work is usually found on architecturally significant or heritage properties, religious institutions, and governments buildings. With respect to residential applications, such items as bay window roofs, ledges, and even complete roofs are completed using various design profiles. Such work is truly custom designed in nature, and represents the pinnacle when discussing cost. The advantage is that the investment in these types of projects are designed to last in excess of 75 years.

Steel Panel Roofing is very popular historically in rural areas, and on certain commercial building applications. Sheet steel manufacturers produce various profiles using galvanized steel, galvalume, and pre-painted galvanized steel (having a factory applied paint finish or coating).

The advantages for using such products are that the panels can often be manufactured in lengths which match the rafter length of the roof. This helps eliminate horizontal seams. Such steel panels are designed to overlap one another at a prescribed rate. Fastening involves the use of coated fasteners and rubber washers to help seal at penetrations points. Other fastening methods are specific to the particular panel style.

Concealed cleats help secure panels in the field against wind uplift. Such manufacturers provide custom accessory flashings for eaves, rakes, hips, ridges, valleys, walls, and roof penetrations.

Various panel profiles are available to include box battens, standing seams, T-battens, and corrugated designs. Colour choices are extensive, and typically have paint and finish processes that are designed to help the metal roof system last in the range of thirty to fifty years.

Eventual failure points tend to be confined to where fastening screw locations are found.
If not extensive, such roofs can often be successfully repaired.

A third category of metal roofing is commonly promoted to the residential and light commercial sectors.
These products are manufactured as various forms of steel or aluminum shingles, or stone coated steel shingles.

This category of roofing products has recently been increasing in popularity among those property owners that are willing to pay more for the concept of a “lifetime” roof. The fact is however, that many manufacturers of such products have come and gone in the past twenty years. While in many instances the products have been good; costs to operate production and inconsistent demand, have not allowed for some to survive in business.

A certain percentage of such products have had technical failures, and or a lack of service options to repair such issues.

When considering such products; it is important for the purchaser to do extensive research to verify the history and financial stability of the company manufacturing the product, and the installation contractor representing the specific metal product type.

In Canada, there are proven national vendors like Vic West and Ideal Metals that are examples of safe and proven manufacturer choices for panel steel and siding products.

Where forms of metal shingles are concerned, products such as Decra (stone coated steel shingles); have successfully been on the market for a number of years.

While many metal shingle products are good, some inter-locking products can have concerns if they are walked on, resulting in “foot- fall” damage. Such products can be crushed down in the surface of the shingle, forcing side locking mechanisms to become vulnerable to water ingress.

As with any type of roofing installation, correct detail work is critical to insuring a proper and lasting project.

Common failure points include terminations at chimneys, dormer side walls, valleys, and transition areas.

What is often promoted in the metal shingle industry; is the method of installing a metal system over an existing asphalt roof. This can possibly be successful however; as a building owner, one should consider the following:

– What if damaged wood decking or dry rot in decking is covered over?
– How does leaving preceding roof layers impact the load capability of the roof moving forward; particularly in regions which receive a lot of snow?
– That it limits the ability to correct sags or undulation of the roof deck.

In general terms for any metal roof system, the building owner should also consider the following:

– Are replacement or repair materials readily available in the future if service is required?
-How will shedding snow or ice accumulation be handled? Items such as snow rail systems, snow birds, and strong guttering products may also need to be factored into the design of the roof assembly.
– Is the roof system designed with proper insulation present, air leakage remediation, and ventilation considerations factored in,to avoid potential perils such as condensation?
– Does metal roofing fit the character of the home, building or neighbourhood?
– What complications are involved, or special flashing requirements will be required ,to accommodate appliances such as skylights or other roof penetrations?
– How will the metal roof system tie into adjacent alternative roof systems such as flat roof areas?
– Will the roof require strapping, and or modifications to perimeter fascia details?

To satisfy these questions in the design stage, it is often suggested to enlist the services of an engineer whom has experience and expertise in the field of metal roofing, and or consulting with the technical divisions of metal suppliers; whom can supply valuable advice. The result will be a well thought- out design, and materials selection, which will result in a durable metal roofing system designed to last for decades.

Among the most popular questions asked by consumers on the subject of metal roofing is cost.

It is important to understand that metal roofing and particularly architectural metals are a commodity driven product, so pricing can fluctuate based on market conditions. It is also to consider that each individual building may require differing specifications based on existing building envelope conditions.

Price will also be influenced by the complexity of the roof design, steepness, and working access surrounding the building, and the height of the building. As an example; the erection of scaffolding may be necessary to complete such a job in compliance with health and safety regulations.

When comparing metal roofing in general terms, to traditional fibreglass laminate shingles; the installed cost should be typically two to three times greater for metal.

Initial installation cost is only one consideration. To properly consider the value of one roof system versus another; it is prudent to consider the life-cycle cost of each roofing product in comparison.
As an example; a standard fibreglass laminate shingle may supply a reasonable life-span of 20 years, where a premium tri-lamiate, designer fiberglass shingle may provide a 40 year lifespan.

In comparison to a specific metal system; the premium fibreglass shingle may still be more cost advantageous, particularly if the roof design is cut up or complex with many details. The opposite could also be true.

In the context of a new build project; a metal roofing system may well prove to be a more cost effective solution under similar design circumstances.

In summary; traditional metal roofing systems remain a proven and enduring option for new build and re-model projects alike. What it does boil down to is budget, perceived value, and aesthetic taste of the purchaser.

To learn more about roofing and related building envelope services; visit www.avenueroadroofing.com

Certainteed
FIRESTONE
VELUX
RAIN PRO
IKO
Heritage Contractors
BBB
Cadar Shake & Shingle Bureau
Select Shingle Roofer
ACMO
WSIB
Canadian Condominium Institute