While an important factor in choosing roofing shingles is the color and design, how well they will protect our home from the elements cannot be understated. High winds can loosen shingles and cause them to lift from and/or blow off of a roof, and this can compromise your roof system by allowing moisture to infiltrate into the building materials below the protective layer of shingles.
So, what measures are taken to resist high wind and keep the shingles on the roof? Let’s begin by ‘looking’ at a shingle.
If you were to hold a conventional roofing shingle in your hand you would notice one or more lines marked across the front of a shingle. These markings indicate the nailing strip, which is the area designated for nailing by the manufacturer.
Just as significant as proper nailing is the strength of the shingle – particularly a factor known as pull-through resistance. Pull-through resistance is a measurement of the force required to pull a shingle over the head of a roofing nail holding it in place. This is why the quality of the components that make up a shingle are so vital, and why manufacturers mention the industry standards their products meet and the independent laboratory tests that their products go through in order to verify the durability of their shingles.
Further inspection of a shingle would reveal a self-sealing adhesive asphalt strip, either on the face or the back of the shingle, which is applied during the manufacturing process. Whereas roofing nails secure the shingles to the roof substructure (typically sheets of plywood called ‘the roof deck’), this adhesive strip secures the shingles together. Shingles are installed in overlapping layers, and the adhesive strip is placed on the area of the shingle which comes into contact with other shingles. Once the shingles are installed, the adhesive strips become thermally activated by the warmth of the sun and create a cohesive bonding of each shingle in a roof system.