Your roof is a major investment in your home and especially an asphalt roof can last you 50+ years. Before discussing the lifespan of a roof, American Construction provides a list to help you understand the anatomy of a roof, discuss its parts and what function they perform in the overall scheme and how they balance each other’s role.
Here are the layers that make up your home’s asphalt roof:
The uppermost layer of your roof is, of course, the multiple layers of asphalt shingles.
Aside from providing an aesthetic cover for homes of most architectural styles, asphalt shingles provide an excellent cover to repel water, absorb the damaging ultraviolet rays and protect the underlying structure from extreme heat or cold. The shingles are mostly composed of a tough fiberglass sheathing underneath that holds together a shingle, the asphalt and the granules made from crushing a specific type of hard rock.
The underlayment lies under the shingles. There are a number of materials used for underlayment. But, the most common one used is called ‘Felt.’ Felt is a thick durable paper which has been soaked and saturated in asphalt. ‘Felt’ provides a secondary, although temporary protection against rain or wind, in case a shingle comes loose or gets torn away in inclement weather. It also acts as a temporary measure to keep the wood underneath it dry during the time the shingles are being added on top of it. The underlayment is rolled horizontally on the roof when installed from the bottom edge. During the installation, significant overlap is allowed to ensure that no water seeps into the wood structure below the underlayment.
The drip edge is an angled aluminum strip that is nailed onto the underlayment at the edge of the roof before installing the shingles. The drip edge, also known as ‘Eave Flashing’ are put in place to guide water to easily flow into roof gutters without getting absorbed at the edge of the roof and building up, especially during winter months.
The flashing does exactly what the drip edge does for the edges of the roof. The flashing is a piece of sheet metal usually made from aluminum or galvanized steel that is placed over joints between a roof and outcropping wall construction on the roof. Objects such as chimneys, plumbing vents, fan vents and other items that stick out of the roof are surrounded by flashing. The purpose of flashing is to use the gravitational force to keep the water from seeping under the shingles via the gap between the roofing and the outcropping object. If properly installed, flashing directs the water away from the joint and down the roof either reaching the ground or the gutter system surrounding the roof. The aluminum or galvanized steel is used for flashing largely because of its durability and the ability to withstand major temperature fluctuations causing it to expand and contract and still maintain the seal it provides to repel the water from seeping in. The metal used usually have a lifespan of over 100 years and can withstand temperature fluctuation of 50+ degrees.
This is the foundation of a roof upon which all the other protective layers are placed. The decking is normally plywood boards attached to the rafters of a house, however, with the changing technology, these could be anything from OSB (oriented strand board), polystyrene, metal or even concrete. The function of all the roofing material from shingles, to underlayment to flashing and drip edge, is to protect the wood decking underneath.
Now that we understand the anatomy of an asphalt roof let’s discuss the factors that impact its longevity:
Whether your house is topped with the affordable asphalt roof shingles or fancier tile or cedar shingles, these shingles and their health ultimately decide the life and longevity of your roof. Please understand that the roof as a whole is a system with essential components that work together to protect your home against outside elements and the system as a whole needs to work, but shingles ensure the overall safety from it all. It is like an armor that protects more sensitive parts inside it.
The asphalt shingles normally have a lifespan of 50+ years, but various factors can make a big difference in it.
Type of asphalt shingle used:
- 3-tab shingles are the least costly of the asphalt shingle family. They are an acceptable choice for a more temperate climate but, they are not suitable for any area that suffers from extreme weather, like high winds, high heat or rapid temperature changes. The shingles themselves can withstand winds of up to 60 – 70 miles per hour. Anything above that and you are risking major roof damage. They are also very sensitive to extreme heat or rapid temperature changes and are not recommended for areas with strong direct sunlight or arid areas with the high heat index.
- Architectural / Dimensional Asphalt shingles are made of thicker material and hence are more durable. They can also withstand stronger winds and are rated for wind speeds up to 110 miles per hour. They can also withstand high heat, direct sunlight and rapid temperature changes.
- Premium Shingles are similar to architectural asphalt shingle with even sturdier construction. They can withstand the winds similar to the architectural asphalt shingles, however, they may have added features such as being better able to reflect sun’s rays (also known as Cool Roof) and better impact resistance capability to sustain damage caused by a hail storm.
Aside from the material used for your roof, the installation of that material has a great impact on its lifespan. Here are some important installation issues to discuss with your contractor:
- Ventilation: A well-vented roof and attic can add or subtract as much as 5-10 years from your roof’s life. In addition, a properly vented roof can help reduce your energy bills, keep the snow from melting prematurely preventing the formation of ice dams on your roof and keep the excessive moisture in the attic from rotting out the decking of the roof.
- Meeting Specific Regional Installation Requirements: Installing your roof correctly for where your house is located and the weather conditions it would encounter makes a big difference in getting the most life out of your roof.
- Correctly Managing the Airflow: As we discussed above ventilation and airflow around your roof is of great importance. Having the correct airflow management using vents, soffit, and other good ventilation routing tools. Good airflow and ventilation are also part of the manufacturer’s warranty requirements.
In conclusion, before answering the question about the life expectancy of your roof, it is essential to understand how a roof anatomically functions and how to protect it from an early demise. This is also true for making your new roof last as long as physically possible with good maintenance, ventilation, and care.