There are all kinds of surprises. Receiving an unexpected compliment? Good. Finding out your roof needs structural repairs? Not so good. The trouble with roofs is that problems aren’t always obvious from the ground. Sometimes a roofer or inspector has to get up on a roof—or even tear off the shingles and asphalt—before they can fully diagnose problems. And by that time, you may already be committed for several thousand dollars of work.

Like most home improvement projects, roof replacements and repairs go best when you prepare for the worst and expect the best—at least budget-wise. Here are a couple of common roofing “surprises,” and what they’ll cost you to fix.

roofing surprise

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What Kinds of Problems Might Roofers Find During a Tear-Off?

Your roofer should send over an inspector before they make you a project estimate—and a good roofer will offer this service free of charge. But even a great inspector can’t predict every roofing issue. Once your roofing team pulls off the shingles or tiles under your roof, there’s a chance they might find damaged underlayment, like one of the following conditions.

  • Rotten decking. The number one issue roofers uncover during a tear-off is rotten or soft roof decking. Decking—in other words, the plywood sheathing that sits below your roof’s shingles—doesn’t always get replaced in every roofing project. In fact, if the decking seems to be in good shape, an honest roofer will usually leave it alone. However, if the roofer finds rotting or soft plywood when they tear off your home’s shingles, they’ll need to put in new sheathing first, before adding the roof on top of that.
  • Inadequate decking. If the roofer starts walking on your roof and finds that the decking is springy or bouncy, they’ll also recommend new sheathing. Modern decking is made from half-inch-thick plywood or OSB panels. But at one time, some local building departments didn’t require anything thicker than ⅜-inch. This thin plywood is now considered inadequate, so a roofer will usually replace it when they find it.

How Much Should I Expect to Spend to Replace Roof Decking?

Your roofer should charge you only for the labor and materials used for a roofing project. A standard piece of plywood roofing sheathing measures 4 x 8 feet, and anywhere from ¼ of an inch to ⅝-inch thick. The thicker the plywood your roofer uses, the more expensive the job will be. Your price could vary depending on how much the roofing company charges for labor, but generally you can expect to spend between $70 to $100 for each sheet of plywood.

A 4 x 8 sheet of plywood covers about 32 square feet of roof area—and the average roof measures about 3,000 square feet. That means new decking could potentially add several thousand dollars to your roofing project.

missing roof shingles

Avoid Problems By Having Your Roofing Inspected Regularly

The National Roofing Contractors Association recommends that you have your roof inspected twice a year—once in the fall, after hot weather has subsided, and once in the spring, after the danger of ice and snow is behind you. You should also have your roof inspected after a big storm, hurricane, or other potentially damaging weather event.

The inspector will get up on top of your roof, and from that vantage point, they’ll be better able to see any issues that need correcting. An inspector can point out the smallest issues to ones that may have grave consequences—everything from cracked shingles to mold. A roofing repair is much more cost-effective than a complete re-roof, so anything you can do to locate issues early will save you money in the long run.

Problems Commonly Uncovered by Roofing Inspectors

Occasionally, a roofing inspector will stumble across a bigger issue, one that warrants a major repair. It can be difficult to notice these kinds of repairs from the ground—and unless your roof leaks, or you find shingles blown off in your yard, you might not realize there was anything going on with your home’s roof at all. Here are the most common larger issues found during roofing inspections.

  • Storm damage. While you’ll probably notice if a branch or other debris piles onto your roof, hail damage can be much more insidious. Your roof shingles are probably rated to protect your roof from the worst hail damage—but small hailstones can still cause problems. Tiny holes in your roof can expose your underlayment to rain and other moisture, which will cause mold, rot, and leaks. An inspector will notice hail damage right away, so you can get your insurance on the case to repair or replace your roof. That’s why it’s so important to have an inspector visit after a big storm. A claim that’s filed too long after the initial weather event may not be covered by insurance.
  • Drainage issues. Another issue you might not be able to detect from below is whether your roof’s drainage system is working properly. A blocked drainage system can result in ponding water on your roof’s surface, which an inspector can see when they get up on your roof. That’s a good thing, since pooling or ponding water can result in eventual leaks or even roof collapse.

The cost to fix these issues depends largely on the scope of the damage. However, an average roofing repair costs between $300 to $1,000—a lot less than a total replacement. When it comes to extending your roof’s lifespan, seeking out and fixing problems early is the best way to go.