What causes shingles to blow off? Do I need to worry about it?

When inclement weather causes shingles to blow off a roof, most homeowners are quick to call someone to r. While this prevents any immediate damage or exposure to the roof deck, it ignores the more important question: why did the shingles blow off in the first place? Answering this question will shed light on the underlying problems that may be affecting your roof.

Most shingles have a wind rating of 110 – 130 miles per hour. This means they are expected to perform appropriately and remain on your roof through severe gusts. The National Hurricane Center places this range in the category 2 – 3 range; these are winds that general accompany moderate to major storms. In short, shingles should only be expected to blow off in the event of major weather events such as hurricanes or tornadoes. If this is not the case, then there is likely a material defect or structural problem.

Below is a video showing what 60MPH wind can do to an old three tab shingle.

Shingles are attached to a roof in two ways. First, roofing nails hold individual shingles securely to the deck. There are different kinds of nails of various sizes and materials, but roofing nails are generally known for having wide, flat heads and short shanks with sharp points. This allows the nail to fasten the shingle without ripping the shingle or damaging the wood. The other method for attaching the shingle is by way of the adhesive strip located on the back bottom side. These adheres to the shingle below it, creating a seal by joining all the shingles together. This provides a strong, water-tight roof.

So what causes shingles to fail and blow off?

There are a number of reasons for shingles to blow off and most require a visual inspection by a qualified roof technician to diagnose. For example:

• Shingles will ultimately fail if installed incorrectly. A common problem is nails being placed too high up on the shingle rather than across the nailing strip. This provides less than adequate holding power as the shingle can be ripped from the nails.
• The average asphalt shingle roof can be expected to last 10 – 15 years, depending on factors including the quality of the materials and exposure to the elements. When a roof is at the end of its lifespan, there are several telltale signs that it is in need of replacement. One such indicator is when adhesive seals no longer join shingles. The shingles effectiveness quickly diminishes and the possibility of  it blowing off increases when the seals no longer hold the shingle in place.
• Loose shingles may also be a sign of significant underlying roof damage. The roof deck is usually comprised of OSB board, plywood sheathing, corrugated metal, or similar durable material. The purpose of the deck is to provide a base for roof coverings and membrane layers to be attached to. If shingles are allowing moisture to penetrate the roof, the deck can become compromised. If it rots or warps, shingle nails can pop, causing shingles to be easily blown off the roof.
• If the roof is new, it is possible that the seal strips have not had a chance to properly set. Depending on the temperature, amount of sun exposure, and quality of the shingles, this can take 4-6 weeks. Most contractors will replace shingles that have blown off of a newly installed  roof at no additional charge. The challenge for the homeowner is to determine if the damage is due to the sealing or because the shingles may have been installed improperly.

It should be clear now that missing shingles are really an indicator of other, more serious problems with your roof. You have two options when it comes to roofs: repair or replace.

Repair: Pros and Cons

Repairing individual shingles or section of roof is a considerably cheaper approach. Damaged shingles can be removed and new ones can be replaced immediately. This avoids the mess associated with a full roof tear-off, and can be completed quickly. Repairing keeps the roof protected but does not significantly affect the homeowner.

While repairing a roof is less expensive, there is often an aesthetic cost. Shingles weather and fade over time. This makes color matching new shingles to old nearly impossible. Patches can be unsightly and obvious when looking at the home. This negatively affects the curb appear. This is especially the case when portions of the roof deck must be replaced, causing large sections of shingles to be replaced as well.

Replacement: Pros and Cons

Let’s face it – if sections of the roof are beginning to fail, it’s an indicator that other areas will not remain secure much longer either. Repairing is essentially delaying the inevitable. A full roof replacement provides peace-of-mind that your hoe is protected. Also, a new roof allows you to take advantage of a wide array of colors, materials, and roofing options that can dramatically change your home’s appearance.

The cost of roof replacement is significant. That is especially the case when there are multiple layers of old roofs. Most building codes only allow for two layers on a home. If you have two, your replacement job will also require a complete tear-off. This adds more cost and time to the job.

Your roof is the first line of defense when it comes to protecting your home for the elements. If you notice shingles blowing off during regular seasonal storms, it may be an indicator of larger problems. If this is the case and you are in the Gaithersburg, Maryland area, we can help. Contact us to have a certified experienced roofer inspect your home.