What Can Cause Waves In A New Roof?
After all of the time, expense and trouble of having a roof installed, you may be disappointed to see that the new shingles are curling and deforming, creating a wave pattern across the roof. Besides being unattractive, this problem can also shorten the lifespan of your new roof and leave it more vulnerable to leaks and missing shingles in the future. There are a few probable causes behind a wavy roof, and with the help of professional roofing contractors, you should be able to both diagnose the issue and begin considering solutions.
Shingling Over Wet Felt
Even when shingling in summer, the felt that rests beneath your roof can be contaminated by moisture. This most frequently occurs when felt is installed and allowed to sit overnight, exposing it to dew and humidity in the morning. Once the shingles are put in place, the water within the felt tries to escape, making the shingles warp and bulge into a characteristic wave. Allowing the roof to settle and dry out can sometimes solve this issue, but it may also require starting over in the affected areas.
Installing a Roof in Cold Weather
It is never a good idea to install a roof near freezing temperatures, both due to the likelihood of precipitation and for the potential of the building materials to expand and contract later. Without leaving enough room to accommodate this, your roof will bend and flex with the changing seasons, and the shingles will not seal properly. It may be possible to correct this in a few localized spots, but widespread damage may require tearing up all of the old work and starting over.
Using Thin Plywood
The industry standard for roofing plywood has varied between 3/8- and 1/2-inch thickness over the years, depending on cost, quality and the contractor in question. Generally, however, 3/8-inch-thick plywood is considered to be the bare minimum to achieve acceptable results. If your felt and shingles are too heavy or the plywood is exposed to moisture, thinner boards are more likely to deform and sag, leading to wide, subtle waves that are nonetheless noticeable on a large roof.
Skimping on Nails
Nails are a major factor in roofing costs, and less scrupulous contractors are often tempted to use as few as possible. Of course, those nails are vital for holding your shingles in place, and without that extra support they may dislodge, warp and buckle even under regular environmental conditions. If you suspect that your roof is in need of a few more nails, this problem can be resolved relatively easily by going back over each shingle and hammering in the proper amount. By taking care of the underlying trouble beneath wavy shingles as soon as you notice them, you may add decades to your roof's lifespan.