Roof Decking

Jan 21, 2019 | Roofing

What is roof decking?

Roof decking is the foundation of your roofing system that connects the roof to your house. It’s the base that lays on top of the structural trusses—the “bones” of your attic—to cover the rafters and support the weight of the roofing shingles.

Most roof decking is made from plywood or a plywood composite known as OSB (oriented strand board).

Although you can’t see it, roof decking is very important to the structure of your home. And if a home’s roof decking is rotting and unable to support the weight of the roof, it can cause some very serious structural issues. In fact, one of the most common issues found during a roof tear-off is soft or rotted roof decking.


What causes roof decking to rot?

Water is your roof’s number one enemy. Since roof decking is made from wood and wood composites, it is particularly susceptible to rotting and water damage when continuously exposed to sustained or excess moisture.

Water seeps into your roofing system in many different ways. Old and worn out roofing shingles, overflowing roof gutters or spouts, torn flashing around chimneys, ice dams or snow accumulation during the winter season, excessive humidity and rising heat in the attic, and inadequate roof ventilation can all allow water and moisture to slowly make its way into your roofing system and lead to rotted roof decking.

What are the signs of rotted roof decking?

One of the most common signs that a roof’s decking is damaged is a roof leak.

Water leakage can lead to ceiling spots or leaks, stains on interior walls, cracked paint, or peeling wallpaper. A quick inspection of the attic might uncover dark water stains on the rafters or in the insulation, or even light passing through holes in the roof. If left undetected, mold and mildew will develop in the walls, ceilings, and insulation.

A sagging ceiling or roof line is another clue that there are major problems with a roof’s decking and the roofing structure. Soaked or waterlogged decking can warp, which can lead to a bowed or wavy roof line and ceiling.

Because your roof is so important and yet, so vulnerable to exposure and weather, 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.

Repair or Replacement?

Thinking about trying to extend your roof’s shelf life by doing a quick patch job? Think again.

Rotted roof decking can’t be repaired. It must be fully replaced.

While replacing a roof is an expensive undertaking, it’s certainly less costly in the long run than replacing stained drywall, waterlogged framing and joists, or water-damaged electrical systems.

Think you have rotted roof decking?




It may be time to replace your roof. When you need a new roof, contact Greenawalt Roofing at 717-898-6000 or visit us online to request an estimate.

Related Posts

Schedule Your Free Roofing or Exterior Estimate Today

Our team is ready to provide a free and transparent estimate for your next exterior project.