Age or damage to your roof that causes moisture build-up in the roof decking can lead to rot, decay, and eventually, damage to other parts of your home. If you have moisture issues in your attic, would like peace of mind when buying or selling a home, or have had potential damage to your roof, like a tree fall or ice dam, it’s best to consult a professional roofer who will have the tools and expertise to diagnose any issues, strip your roof, and repair the damage.
What causes roof rot? Roof decking (or sheathing) is the thin layer of wood that spans the roof’s trusses and supports the shingles and other roofing materials. Most roof decking is made of plywood or oriented strand board (OSB). These materials absorb moisture easily, so when either a leak in the roofing material or a build-up of condensation are routinely exposing the sheathing to moisture, eventually, the sheathing may rot or decay. Since the decking is hidden by the shingles, these problems can be tough for homeowners to spot until the damage has become severe.
Severe damage to roof sheathing can affect the entire home. Fungus or mold build-up may affect the air quality in your home. Attic insulation may absorb moisture from the roof, which reduces the energy efficiency in your home. Moisture may even spread to and damage other systems, including the home’s electrical system, and unchecked wet or dry rot can spread to other wood, possibly affecting the structure itself.
So, how can you spot wood rot in a roof deck? Inspect the inside of your attic and pay close attention to the underside of your roof deck: if you see dark spots, black, white, yellow, brown or gray discoloration, if the wood feels soft, spongy, or crumbly, or if you notice a damp or musty smell, you likely have rot in your roof deck. Wet rot tends to make the affected area look discolored or darker than the wood around it. Dry rot often looks like a fungal growth, and the wood may look cracked and dry. A sign of more severe damage is often a visibly bulging or bowing roof, where the sheathing has absorbed moisture and either expanded, pushing the shingles upward on the outside, or it has sagged down between the rafters.
What if you suspect roof damage? A home inspector or a roofing professional can verify the condition of your roof deck. They may be able to diagnose the problem from inside your attic, or they may remove a few shingles to check the condition of the sheathing.
How is rotted roof decking repaired? Repairing a rotted roof deck is a professional roofer’s job. A roofing professional will also be able to resolve the problem that’s causing moisture build-up, like a leaking skylight or damaged or aging shingles.
Your roofers will:
Remove the roofing: A professional roofer will first use a roof removal tool like Shingle Eater to remove all of the roofing material above the affected area. This includes stripping away the shingles, prying away flashing with a special tool like the Shingle Eater Junior, scraping off the underlayment, and removing roofing nails. Roofing materials vary and may include several layers of old shingles. The reinforced Demo Eater allows the roofer to quickly remove all of them, quickly stripping the roof back to the sheathing all around the damaged area. Exposing the sheathing allows the roofer to fully assess the damage to the roof deck and determine how much of the sheathing is rotted and needs to be replaced.
Cut out rotted decking and replace: Your roofers will need to saw a hole in the rotted decking without damaging the rafters below. The may use a Demo Eater to pry up the damaged sheathing and decking and pull the old nails that were securing it. They will then cut new sheathing to fit, ensuring that each replacement piece is supported by preferably 2 rafters. The replacement material should be the same thickness as the original sheathing so that the shingles lay flat. Each piece will be custom cut to fit tightly against the existing material, and will be secured to the rafters with nails or screws.
Replace the roof materials: Your roofer may apply a rot-resistant treatment to the wood surrounding the repair, or apply waterproof tape to seal the seams where old and new decking meet. They will then replace the underlayment, overlapping it with the existing to prevent leaks, and replace the flashing and shingles.
If you suspect your roof deck may have been exposed to moisture from inside or out, consult a roofing professional to diagnose the damage and repair it quickly. A roofing professional will have the experience and the professional grade tools, like the Original Shingle Eater roof stripping tool, to get the job done before the problem spreads.
