Metal Roofing

First, let’s take a look at the benefits of metal roofing. Choosing the right metal roof is critical but, even before that, you must know why you’re choosing metal in the first place. As we discussed, it is often (though not always) a higher investment than more common roofing materials. Why are tens of thousands of homeowners choosing metal each year?

Weather Resistance And Other Benefits

The roofing industry is driven by extreme weather. Whether strong winds and storms, hail, snow, ice, or brutal sun, the weather is what makes roofing materials break down. Chances are you have experienced this and that is what has driven you to investigate metal as an option. Let’s look at how metal stands up to weather extremes.

Heat and Sun

While particularly damaging in southern exposures and at high altitudes, heat and sun play huge roles in the degradation of most roofing systems. Ultimately, most roofing systems fail because the dry out, become brittle, and crack with age. Metal roofing systems are completely impervious to this type of damage. They will not curl, crack, or become brittle when exposed to sun and heat. Additionally, today’s coating technology offers a variety of finishes which maintain their integrity and color very will when exposed to heat and sun.

Wind Resistance

Recent devastating hurricanes in our country have brought a lot of press to this subject in recent years. We have all see the video footage of roof damages. Fact is, in these extreme weather events, the roof is a terrible place to be, for all product genres. Does metal really perform better than other products? Let’s take a look at the issues involved.

It’s important to understand that, in a hurricane or other windstorm, there are many things that happen which affect the roof. Of course, you have actual physical windspeed blowing into the roof from some angle. This wind puts strain on the metal panels as it hits them but, sometimes even to a greater degree, it puts uplift pressure on the backside of the roof. Next, you can often have structural movement occurring which will impact roof performance – some homes are built better than others to withstand this. Structural movement can cause roof panels to disengage, particularly if they were not designed to allow for it. Additionally, improper attic venting can cause attics to literally explode. No roof covering will be able to handle that. And, of course, windblown debris striking the roof can compromise its performance as well.

In order to verify their wind resistance, metal roofing products are subjected to uplift tests which simulate actual wind occurrences. This is done through what is called the “bag test”. With some variations, a section of roofing is installed in a laboratory with plastic bagging between the metal and the roof decking. This plastic bagging is then filled with air pressure to determine at what point the metal roof panels disengage. The point of disengagement can be used to approximate a failure point in terms of windspeed.

Some metal products have actual mechanical interlocks between the panels. These products, if properly designed and installed, will often perform better in uplift test than will overlapping panels or panels with a “slip lock” rather than a true interlock. Some products with overlapping panels, though, will have fasteners driven right through the overlap and that can make them perform very well as well.

One important factor to remember when considering the wind performance of any roofing material is aging. Many roofing materials soften or become brittle with age. As that happens, their ability to withstand extreme winds lessens. Metal products, on the other hand, retain their strength and wind resistance very well as they age. A 30-year-old metal roof will likely withstand wind the same as a brand new metal roof. That is nowhere even close to the case with most other roofing materials. For all of these reasons, property owners in wind-prone areas are increasingly turning to metal as their roof system of choice.

 Snow and Ice

Many people may not think about it but snow and ice are among the worst that mother nature can throw at a roof. They cause degradation of materials, failure of sealants, and ice damming can cause severe home damages.

Metal roofing is known for its ability quickly shed snow loads. Typically this happens when the sun comes out and radiant heat passes through the snowload, warming the metal a bit. In some cases, it may be advisable to have snowguards on the roof which are small protrusions designed to hold the snow a bit and break it up into smaller chunks when it does slide. This can be a good idea particularly over doorways and delicate shrubbery.

Homeowners are cautioned that, while metal roofing tends to shed snow quickly, it still doesn’t make up for the lack of attic insulation and ventilation which can result in ice damming on the roof. Generally speaking, snow and ice on a metal roof will not cause damage but if ice damming occurs over the eaves and water starts to pool and freeze higher up on the roof, it can be a challenge for any roof system. When replacing your roof, it is a good idea to ask your contractor whether you need any additional or improved attic ventilation to guard against winter damages.

Lightning

It is common for homeowners to wonder whether a metal roof might attract lightning. Fact is, metal conducts electricity but it does not “draw” it. There is no evidence that metal roofing puts a home at greater risk of a lightning strike. Typically, lightning will hit the highest object around and rarely is that the top of the house. Just the same, metal roofs can be grounded by a lightning protection specialist if desired.

Hail

Metal roofing is widely respected for its hail resistance. While there can certainly be storms from which no roofing material will escape unscathed, metal roofing offers good protection from leaks even if aesthetic damages do occur. The most widely-accepted test of hail-resistance is Underwriters Lab (U.L.) 2218, a steel-ball drop test that simulates the effect of hail impact on roofing products. Metal roofs pass U.L. 2218 at Class IV, the highest rating. As a result, homeowners in many hail-prone states can obtain discounts on their insurance premiums. Additionally, unlike other roofing materials, metal roofing resists hail damage even as it ages. This is another big advantage for metal.

Fire Safety

Most metal roofs are approved for Class A, B, and C fire ratings. In some cases, a special underlayment may be required to meet certain code and fire classification requirements. However, metal roofing is widely recognized for its resistance to airborne sparks and burning debris. Particularly if you have a wood shingle or shake roof currently, you may enjoy a lower insurance premium with a metal roof. Additionally, in the event of a fire inside your house, the low weight of metal roofing minimizes the possibility of roof cave- in as the structure weakens. This can help save your home and belongings, providing firefighters with greater opportunity to put out the fire.

Earthquake Resistance

With weights from 45 pounds for aluminum roofing up to a maximum of about 125 pounds (per 100 square feet), metal can be as little as 1/20th the weight of other roofing materials. It is generally the lowest weight roofing available. This can help protect the structure in the event of seismic activity when oftentimes homes are destroyed under the weight of heavy roofs. Additionally, metal’s low weight can be a positive for older structures as well.

The Bottom Line

The industry is seeing a rapid increase in the use of metal roofing in areas prone to severe weather. This is because the “proof is in the pudding.” People are seeing metal systems out-perform other roofing systems on a regular basis during weather occurrence of all types. Products that perform well in severe weather will also, naturally, do very well in more moderate weather, too.