Have you noticed that your shingle roof has a “wavy” appearance? You might think it’s just an indication that it’s time for a roof replacement, but even brand new roofing can have this problem. If your roofing contractors don’t keep a careful eye on the plywood sheathing beneath the shingles, new shingles could actually make a wavy roof all the more noticeable.

So what causes wavy roofing?

Shingles are attached to sheets of plywood sheathing. This plywood spans the gaps between the trusses, or the roof’s wooden framing. If your plywood sheathing is too thin, warping can occur. Moisture combined with weight from snow buildup (a common occurrence for Nashville winters) can gradually cause the sheathing to sag over time. The roof will not sink where there are rafters or trusses, but in between them, where the plywood is weakest. This alternation between sagging areas and trusses results in the unsightly wavy appearance.

How can wavy roofing be avoided?

The thickness of the plywood used for sheathing plays the biggest role here. To avoid sagging during the lifetime of your shingle roof, a minimum thickness of 5/8″ is recommended. This might mean that you’ll also need to replace your sheathing the next time you’re in need of a residential roofing job. If replacing the sheathing isn’t an option, thinner plywood can be reinforced with 2×4 boards between the trusses within the attic. When walking or standing on a roof with thin sheathing, you can also lay a sheet of plywood down to distribute your weight more evenly, hopefully helping you to avoid a wavy roof.

At Sparks Roofing, we don’t just perform roofing work that looks good when it’s finished. We also make sure our Nashville and Clarksville area customers are fully aware of roofing problems like this that may occur in the future, allowing them to make informed decisions. Contact us today for a free estimate!