There's a thin sheet of wood between your roof shingles and the rest of your house called the roof deck, and when it's exposed to moisture, it may develop wood rot. Left untreated, this rot can damage the structural integrity of the wood over time, which can lead to roof leaks and water damage.
Ensuring proper attic ventilation and using rot-resistant building materials can help prevent wood rot. Once it's identified, however, it's important to replace the roof sheathing as soon as possible to avoid further damage. Read on to look at roof deck wood rot more closely, including how to identify the signs of an issue, what to do next, and tips for prevention.
Understanding Wood Rot
Wood rot is caused by several species of fungi that grow and feed on wood in the presence of moisture. This causes wood to lose its structural integrity and strength, often accompanied by discoloration. There are three main types of wood rot: wet rot, dry rot (also called brown rot), and white rot.
Wet Rot
Wet rot often appears as black discoloration in locations exposed to excessive moisture (hence the name) and may feel soft or spongy to the touch. If the area has dried out, the wood will crack and crumble when touched. Wet rot can also cause paint to bubble and crack.
Dry Rot
Dry rot, also called brown rot, is typically characterized by brown discoloration and can cause cracking and splitting. As the name implies, the damaged area is dry—not wet—and the wood may have a powdery appearance. You may also notice a white or yellowish residue, the remains of the fungus growth.
White Rot
White rot appears as white spots or streaks and gives wood a spongy feel.
Signs of Roof Deck Wood Rot
The signs of wood rot include:
- Soft or spongy texture
- Sagging
- Cracking or crumbling
- Discoloration
- Growths or powder
- Musty odor
The most common cause of wood rot is moisture, either from a roof leak or condensation in the attic. To get to the roof deck, moisture must come through the roof's shingles and underlayment. This typically occurs when debris or inclement weather damage the roof. Susceptible areas include seams, edges, and around flashings and penetrations.
The attic is the best place to look for signs of wood rot. From there, you can safely inspect the bottom of the roof deck. Roofers may also notice soft spots or dips in the roof deck when they're walking on the roof during inspections or routine maintenance.
Preventing Roof Deck Wood Rot
Of course, as with most things, it's best to prevent wood rot from occurring in the first place. Here are some tips to help proactively prevent wood rot.
Ensure Proper Ventilation and Moisture Control
Attic and soffit vents help maintain both the temperature and moisture content below the roof deck. Ensuring that your system has the proper amount of ventilation for your roof's size is key to preventing damage and leaks from ice dams. If you aren't sure how much ventilation you need, call a professional roofer for an assessment.
Schedule Regular Roof Inspections and Maintenance
Have your roof inspected by a professional roofer at least once a year and after storms or other weather events. You'll also want to get an inspection when you're buying a home. Maintenance may include clearing gutters and downspouts, removing debris, and inspecting the roof's surface for missing or damaged shingles, damaged flashings, or soft spots. Addressing issues early on can help prevent future damage and save money on large repairs.
Choose Rot-Resistant Woods and Building Materials
Some species of wood are naturally more resistant to rot, such as cypress, cedar, juniper, white oak, and redwood. You may also consider composites, which are a mixture of wood and plastic.
Rely on a Professional for Wood Rot Repair
If you already know you have wood rot on your roof deck, consult a professional. While you may be tempted to cut costs with a DIY approach, contacting a professional roofer to repair wood rot is ultimately a cost-effective decision. Mistakes can lead to significant damage down the road. When it comes to the integrity of your home and roofing system, their expertise can save you time and money in the long run.
Professional roofers have the training, experience, and knowledge to accurately assess the extent of damage and determine the required scope of repairs. You'll know exactly how much work needs to be done, how long it will take, and what it will cost before the work begins. Roofers also have access to specialized tools and construction techniques that help streamline repairs, provide quality installations, and keep workers safe. Safety is a primary concern when working off the ground, and contractors have the necessary equipment and knowledge to mitigate these hazards.
Finally, by hiring a professional, you get a warranty on labor and materials. You also get peace of mind knowing the repair was done correctly and according to local regulations.
Common Steps to Treat Wood Rot
Here are the steps a roofer will typically take to repair wood rot.
Identify the extent of the damage. First, they'll remove the shingles and underlayment around the rotted area to determine the extent of damage. If flashings are in the affected area, they'll remove them as well.
Remove the rotted sheathing. Next, they'll cut out and remove the rotten sheathing, leaving the rafters below intact.
Replace the roof sheathing. They'll then install new plywood or oriented strand board sheets and secure them to the rafters with nails or screws. They may also add a wood sealant or preservative to help protect the sheathing from moisture intrusion in the future.
Install remaining roof system components according to code and local climate requirements. The roofer will then install the remaining components of the roof system over the new decking, making sure there are no gaps or seams where moisture could intrude.
Keeping Structural Problems at Bay
Roof deck wood rot can be damaging, leading to roof leaks and potential structural problems—especially when it's not addressed promptly. Regularly inspect your attic space for signs of wood rot, and schedule annual roof inspections. If you have any concerns, contact a GAF-Certified* contractor to get ahead of bigger issues. They can let you know exactly what to expect before work begins.
*Contractors enrolled in GAF certification programs are not employees or agents of GAF, and GAF does not control or otherwise supervise these independent businesses. Contractors may receive benefits, such as loyalty rewards points and discounts on marketing tools from GAF for participating in the program and offering GAF enhanced warranties, which require the use of a minimum amount of GAF products. Your dealings with a Contractor, and any services they provide to you, are subject to the GAF Contractor Terms of Use.
