There are many factors that can influence the life expectancy of the roof sheathing and covering.
All roof coverings, regardless of materials, are susceptible to additional variables, such as:
We have all seen pictures on the news of homes in “Tornado Alley” — the geographic region that lies between the Rocky Mountains and the Appalachian Mountains — with their roofs blown off, but it is not unusual to see weather damage in all areas of the United States, as well as in various regions around the world. Sometimes, severe weather damage will leave behind ripped shingles and dislodged tiles affecting just one or two areas of a home’s roof but, occasionally, there can be more widespread damage that is easier to spot.
This is very common and most often caused by overhanging tree branches. It can also be inflicted by falling masonry, and cracked tiles and shingles from people being on the roof.
This category of rapid deterioration of the roof covering can be attributed to airborne pollutants that are prevalent in industrial areas, as well as from the acidity of pine needles breaking down on the roof’s surface.
The direction that the roof faces can have a significant influence on the long-term condition of the roof. For example, south-facing roof planes tend to show signs of overheating, particularly those with asphalt shingles. North-facing roofs and those in the shade tend to have more algae- and moss-induced problems, both of which will shorten the life of the roof covering.
Poorly vented roofs, especially those over cathedral ceilings which are hard to ventilate, will show signs of over-heating, and may also show signs of moisture damage.
Inadequately insulated attics will also promote rapid failure of the roof covering due to issues such as ice damming in colder climates.
Both the roof sheathing and framing can sometimes indicate structural issues revealed on the roof’s surface. Such problems may be as apparent as cracked shingles or tiles above a structural defect. More commonly, there will be a wavy look to the roof caused by thin roof sheathing that is over-spanned.
All roofing systems are only as good as the installer, and it is not uncommon to see all types failing due to poor fastenings or other installation problems.