Wood rot can jeopardize a house’s structural integrity if not addressed promptly. Fortunately, it’s relatively easy to identify and repair rotting wood before it becomes a major problem. In the video above, This Old House’s general contractor Tom Silva shares expert techniques for spotting and fixing wood rot, helping you maintain a sturdy and well-maintained home.
Top Signs of Wood Rot
Regularly inspect areas prone to moisture accumulation, such as:
- Areas where wood meets the ground
- Fascia boards behind gutters
- Joints in exterior trim
- Window and door sills
Look for discoloration, warping, or any visible fungal growth, as these can be signs of wood rot. In addition to these visual indications, be mindful of a musty smell, as it could reveal hidden rot within walls or beneath floors. A moisture meter can also help identify areas with high moisture levels, enabling you to act before rot becomes visible.
Here are some other early indicators to look out for when identifying wood rot.
Peeling Paint
Peeling paint is often the first sign of wood rot. When water penetrates the wood, it can cause the paint to separate from the surface. As the sun dries the board, moisture pulls through the wood, causing the paint to flake off. Peeling paint can indicate underlying moisture problems that, if left untreated, can lead to extensive wood rot.
Soft or Punky Wood
Advanced wood rot, characterized by soft, punky wood that flakes off easily, often accompanies other issues like carpenter ant infestations. Carpenter ants, attracted to damp or wet wood, can exacerbate existing rot problems.
Soft wood typically occurs in areas frequently exposed to water, such as window sills, door frames, and the bottom edges of wooden siding. If a screwdriver or similar tool easily penetrates the wood, rot has taken hold and requires prompt attention.
When To Replace vs. Repair The Wood
Once you’ve identified rotting wood, you must decide whether to replace or repair it.
Typically, you’ll want to replace wood when the damage is extensive, the area is accessible, or the component is readily available. Common replacements include window and door trim, fascia boards, and decking. When rot has compromised the structural integrity of these components, replacement is usually the best option.
Replacing wood often involves removing and installing entire boards, frames, or sections of a structure. This process can be labor-intensive, especially for large or difficult-to-access areas, but it guarantees that the issue is fully addressed and prevents further deterioration.
Though replacement may require more effort and time, it is often the most effective way to maintain your home’s longevity and safety. Installing new, durable materials prevents future issues and preserves the structural integrity of your property.
When to Repair
Opt for repair if you’re dealing with localized rot or when replacing the entire piece would be a major undertaking. You’ll need to make sure that enough good wood remains to support the repair. Window or door sills are often suitable candidates for repair. Replacing them can be complex and time-consuming, especially if the damage is minimal.
Remove as much of the damaged wood as possible before starting the repair. Leaving even a small amount of rot can cause the problem to resurface, potentially leading to more extensive damage over time.
Use tools like a chisel, scraper, or sandpaper to reach fresh, solid wood. This thorough approach makes the repair durable, leaving the remaining wood strong enough to support the structure.
Tools and Materials for Wood Rot Repair
You’ll need the following tools and materials to repair rotted wood:
- Two-part wood filler
- Primer and paint
- Protective gear (gloves, dust mask, safety glasses)
- Putty knife
- Sandpaper or palm sander
- Wood restorer
Silva recommends products manufactured by Bondo for wood rot repair. However, many other brands offer similar products. Select high-quality materials to maximize the longevity of your repair. When choosing a wood filler, look for one specifically designed for exterior use that is waterproof and resistant to shrinking or cracking.
Repair Rotted Wood in Place
Follow these steps for an effective wood repair:
- Remove as much rotten wood as possible using a scraper, chisel, or sandpaper.
- Clean the area thoroughly to remove any debris.
- Apply a wood restorer to strengthen the remaining wood fibers. This step helps to solidify and stabilize the wood, providing a better base for the filler.
- To rebuild the damaged area, use a high-quality wood filler. Apply it in layers, allowing each layer to cure before adding the next.
- Once the filler has dried, sand the repaired surface until smooth. Use fine-grit sandpaper to achieve a finish that blends seamlessly with the surrounding wood.
- Prime and paint the repaired area to protect it from future damage. Choose a high-quality exterior paint and primer for long-lasting protection.
Prevent Future Wood Rot
After repairing rotted wood, take proactive measures to avoid future damage. Install proper flashing around windows, doors, and other openings, and maintain gutters and downspouts to direct water away from the house. Apply a high-quality, water-repellent sealer to all exposed wood surfaces annually, including the backs of fascia boards, window sills, and trim, to seal out moisture and extend the life of your wood components.
Keep shrubs and plants trimmed away from the house to promote air circulation, and address any plumbing leaks or moisture issues promptly. To enhance durability, use pressure-treated wood for outdoor structures. This wood contains preservatives that protect against rot and insect damage.
In addition, consider using deep-penetrating wood preservatives for extra protection against moisture and insects and regularly repainting or restaining your wood surfaces. Check for proper ventilation in attics and crawl spaces to reduce moisture accumulation and avoid contact between wood and the ground to further minimize the risk of rot.