The Pros and Cons of Metal Roofing

By Frank G. Ross

Recently I inspected a cabin for a client who asked about the metal roofing.  She was unfamiliar with it and wondered about the positive and negative aspects of a home with a metal roof.  Fortunately I was able to tell her that there are many more benefits than drawbacks. 

Long life expectancy, resistance to hail, wind, insects, rot and fire, light weight, speedy installation, and energy efficiency are some of the positive factors.  Negatives include cost, denting, possible trouble matching color, and perhaps noise.  Also because metal will expand and contract with the temperature, newer roof products have fastening systems which take that into account.  Without that, fasteners may tend to work loose over time.

When properly installed a metal roof can last as long as the house.  Durable enough to protect the home from water, wind and heavy snowfall, they are also low maintenance and not susceptible to insects which could destroy other roof systems. Due to the fact that metal is noncombustible; this roof type receives the highest rating for fire safety.  Many manufacturers offer 20 to 50 year warranties.

In terms of load, metal roofing is very light.  Compared with tile or concrete tile which weighs 750 to 900 pounds per square (an area equal to 100 square feet) or asphalt shingles which weigh in at about 240 to 400 pounds metal weighs a mere 50 to 150 pounds per square depending on the type of metal used.  Because of this metal roofing may be applied over an existing roof saving the time and expense of a “tear-off.”  Also, since the metal comes in large sheets it is quicker and easier to install than other types of roofing which must be installed one small piece at a time.

Metal roofs have the added advantage of reflecting the sun’s radiant heat.  Keeping the attic cooler in this fashion may also reflect a savings in the homeowner’s bank account due to lower air conditioning costs.

The biggest drawback with metal roofing is the cost which will be roughly equivalent to other premium roofing products.  But since the roof may never need to be replaced during the life of the home, it pays for itself over time.

One of the properties of metal is that it is malleable or bendable if hit with enough force.  So it is possible that a metal roof could be dented if hit hard enough with a golf ball or with a large enough hailstone.  A loose piece of roofing could also be caught and bent by a very strong wind.  In that case replacing the damaged section is more than just a simple repair since the whole sheet would need to be changed out.

An additional concern people may have with a metal roof is the possibility of noise.  Won’t it be noisy in a rainstorm?  Yes, it would if all you had covering the home was the metal.  However, the metal will likely be attached to some type of roof decking and if the attic is also insulated, the noise will be deadened further.  My own home has a metal roof and excessive noise has never been a problem.  In fact we may not even know that it is raining unless we see the lightning and hear the thunder because the sound of raindrops is so muted.

One other factor that could become an issue if the home is added onto could be matching the color of the roof.  If the roof has been exposed to the sun for a number of years, the color could have been altered and it may be difficult to match a new roof to and old one.  This would also apply to situations when a section of the roof needs to be replaced due to damage.

Having satisfied my client’s curiosity about metal roofs, I ascended my ladder to take a closer look at her roof.  But since metal roofs are slippery, wet or dry, I did not climb onto it. Instead, I did as thorough a check as I could from the roof edge and with binoculars.  And on this cabin the roof checked out fine.

Frank Ross is a Certified Utah Home Inspector for Pillar to Post Professional Home Inspection and a full member of the National Association of Certified Home Inspectors and a member in good standing with the Utah Better Business Bureau.  Readers may contact Mr. Ross at (435) 867-6400 or frank.ross@pillartopost.com