Finding a dark, soft, or crumbly spot on your home’s exterior can be alarming. “Wood rot” is a common fear for any homeowner in our damp Pacific Northwest climate, and for good reason—if left unchecked, it can lead to serious structural damage. The key to dealing with it is to understand what causes it, how to identify it properly, and to know the difference between a simple fix and a problem that requires a professional.
This guide will empower you with the knowledge to identify, prevent, and understand the proper treatment for wood rot, helping you protect your home.
The #1 Cause of All Wood Rot: Uncontrolled Moisture
Wood rot is not a natural aging process; it is decay caused by fungi that consume the components that give wood its strength. But these fungi have one critical requirement to survive and thrive: water. Wood that stays dry will never rot. Therefore, every case of wood rot is, at its heart, a moisture problem. The most common sources are:
- Clogged gutters overflowing onto fascia and siding.
- Cracked or failing caulk around windows and doors.
- Leaking roofs or improperly installed flashing.
- Poor ventilation in crawl spaces or attics, leading to condensation.
- Siding that is too close to damp soil or sprinkler systems.
Is It Dirt, Mildew, or True Rot? A Simple Field Test
Not every dark spot on your wood is a catastrophe. Here’s how to tell the difference:
- Try to Clean It: If the spot wipes away with a damp cloth, it’s likely just dirt or algae.
- Look for Surface Discoloration: If you see black or green spots that seem to be on the surface of the paint, it’s likely mildew. Mildew indicates a moisture problem but has not yet compromised the wood itself.
- Perform the “Screwdriver Test”: Gently press the tip of a screwdriver or a key against the suspect area.
- If the wood is firm and resists the pressure, it’s likely sound.
- If the wood feels soft, spongy, or crumbles easily, you have true rot. The fungus has already damaged the wood’s internal structure. For a deeper understanding of the types of decay, see our guide on Dry Rot vs. Wet Rot.
Wood Rot Treatment: DIY Fixes vs. Professional Solutions
- When DIY Can Work: If you have a very small, purely cosmetic spot of decay (e.g., the size of a quarter on a non-structural decorative trim piece) and you have already fixed the moisture source, using a DIY epoxy filler or wood hardener can be an acceptable cosmetic patch.
- Why DIY Fails for Significant Rot: Epoxy fillers do not restore structural strength. Using filler on a rotted window sill or deck post is dangerous because it masks the underlying weakness. Furthermore, if any fungal spores remain in the surrounding wood, the rot will simply continue to grow around the epoxy patch, hidden from view.
- The Professional Solution: The only correct and permanent treatment for significant wood rot is the complete surgical removal of all decayed wood and replacement with new, treated material. This is the foundation of our professional dry rot repair service.
(H2): How to Stop Wood Rot Before It Starts: A Prevention Checklist
- Clean your gutters at least once a year.
- Inspect and maintain the caulk around all windows, doors, and other exterior penetrations.
- Ensure your crawl space is dry and well-ventilated.
- Keep sprinklers from spraying directly onto your siding.
- Trim back shrubs so they are at least one foot away from your house to promote airflow.
- Consider a professional dry rot inspection every 3-5 years to catch problems before they become severe.
When to Call a Wood Rot Specialist
It’s time to call a professional if you find any wood that is soft or crumbly, if the affected area is larger than your fist, or if the rot is on any structural component of your home. If you suspect you have a rot problem, it’s always best to get an expert opinion.
If you’re in the Seattle area, contact a local dry rot specialist for a thorough assessment.