By: Kevin Duffy
In our previous articles on roofing systems, we discussed single ply, roll roofing, liquid applied, asphalt shingles, clay tile and slate roofing. This final article on steep slope roofing provides an overview of metal roof systems.
There are variations of metal roofs. Corrugated metal roofs, often seen on industrial buildings, are well secured but may not be visually pleasing. Sheet metal tiles can be decorated to look like clay or stone tiles. While considered more aesthetically pleasing, these lightweight tiles can blow away during heavy storms, if not properly secured. The most popular metal roof is the standing seam system. The standing seam refers to the ridge that is formed by the interlocking of metal sheets at intervals ranging from 12a to 36a. This ridge creates a seal and prevents water from constantly running along the joint.
Standing seam roofs are popular in colder climates. Metal panels are extremely slick and shed snow very easily. In northern climates where average yearly snowfall can reach 10 feet or more, it is important to reduce the weight of snow build up.
Given the fact that they are inherently fireproof, Metal roof systems tend to have good fire ratings. In fact, their rating is less dependent on the inherently fireproof metal roof than the composition of the deck underneath. Metal roofs are also extremely light and do not require additional structural support the way clay and stone tiles might. Metal roofs are also environmentally friendly since up to 65% of the system can be made of recycled materials.
Contrary to popular belief, metal roofs often reduce energy costs. In the warmer months, the metal tends to reflect more heat than other roofing products, thus keeping cooling costs down. Heating costs in colder months are lowered because the metal reflects the buildingas internal heat back into the building. Most experts agree that the average energy savings is approximately 20% over an asphalt roof system.
Initial cost is the biggest disadvantage of a metal roof system. Due to the costs of metals such as aluminum and copper, metal roofs can be significantly more expensive than other steep slope roof systems. Another drawback of a metal roof system is that, unlike asphalt shingles, they cannot absorb the impact of hailstones and are susceptible to denting during hailstorms.