If you’ve noticed sagging, leaks, or musty smells from your attic or roof area, you may be facing a serious issue: rotting wood under your roof. Not only is this a structural hazard, but ignoring it could lead to catastrophic damage—and a costly full-roof replacement.
At Litespeed Construction, a leading Knoxville, TN roofing company, we’ve seen firsthand how untreated wood rot can compromise roof safety, energy efficiency, and home value. We wrote this comprehensive guide to help you understand how to identify, remove, and replace rotten wood—safely and professionally.
Key Takeaways
💡Rotten wood under a roof is usually caused by leaks or poor ventilation, and must be replaced immediately to avoid spreading.
💡Roof decking and structural components are the most commonly affected areas and require precise removal and replacement.
💡Licensed professionals like Litespeed Construction are equipped to do this work safely and to code.
💡Learn the step-by-step process, red flags to watch for, and how to protect your home long-term.
What Causes Rotten Wood Under Roofs?
Rotten wood is typically the result of prolonged moisture exposure, which leads to fungal growth. Common causes include:
| Cause | Description |
|---|---|
| Roof Leaks | Often caused by missing shingles, flashing damage, or old age |
| Clogged Gutters | Causes water to back up and pool near the roof edge |
| Poor Ventilation | Creates humidity in the attic, perfect for wood rot |
| Storm Damage | Heavy rain and hail can compromise waterproof barriers |
🔍 Fact: According to the U.S. Department of Energy, poor attic ventilation is one of the top causes of hidden roof moisture and wood rot (Energy.gov).
Signs That You Need to Replace Rotten Wood
Before any repair begins, knowing what to look for is critical. Below are the most common red flags:
- Spongy or soft decking under shingles
- Water stains or mold in the attic
- Visible sagging on the roof
- Shingles that curl or buckle
- Musty odors in upper floors or attic
Tip: Regular roof inspections by a certified Knoxville roofing contractor like Litespeed Construction can prevent expensive repairs later on.
The Dangers of Ignoring Rotten Roof Wood
Failing to replace rotten wood in your roof can lead to:
- Structural Collapse – Support beams and trusses can fail
- Pest Infestation – Termites and rodents are drawn to decayed wood
- Mold Growth – Increases allergy and respiratory risks
- Insurance Denials – Most policies exclude damage from poor maintenance
👉 According to FEMA, mold can begin growing in as little as 24–48 hours on wet surfaces (FEMA.gov).
How to Replace Rotten Wood Under a Roof: Step-by-Step
The process to replace rotten wood under your roof involves several critical steps. Here’s how a professional like Litespeed Construction handles it:
1. Inspection & Assessment
- Full roof inspection to identify affected areas
- Moisture readings with specialized equipmentw
- Check for structural integrity
2. Roof Decking Removal
- Remove shingles and underlayment
- Cut out affected decking, rafters, or fascia
- Proper disposal of rotten wood (per EPA guidelines)
3. Replacing the Wood
- Use pressure-treated lumber or OSB decking
- Install to code with nails/screws rated for exterior use
- Apply waterproof membrane over new wood
4. Reinstallation of Roofing Materials
- Replace underlayment
- Reinstall or upgrade shingles
- Seal flashing and vents
5. Final Inspection & Cleanup
- Ensure structural soundness
- Clean up job site
- Provide warranty and maintenance plan
✅ EPA Note: All wood waste, especially mold-contaminated wood, must be disposed of according to EPA construction waste guidelines.
Roofing Material Considerations for Replacement
When replacing roof decking, the type of roofing system you have matters:
| Roofing Type | Replacement Wood Considerations |
|---|---|
| Asphalt Shingles | Plywood or OSB decking common |
| Metal Roofing | Requires exact screw alignment with decking |
| Tile Roofing | May require reinforced decking to handle weight |
FAQs about Replacing Rotten Wood Under a Roof
Signs include sagging areas, mold in the attic, and soft spots when walking on the roof.
It’s not recommended. This is structural work requiring safety gear, permits, and experience.
Most jobs take 1–2 days, depending on how extensive the rot is.
Typically OSB (oriented strand board) or CDX plywood is used, depending on roof pitch and weight.
Most policies do not cover rot caused by neglect, but may cover damage from a storm or sudden leak.
Costs range from $300 to $1,500, based on square footage and labor rates.
Only if the source of the leak is also fixed—flashing, shingles, and gutters must also be inspected.
Ensure proper ventilation, clean gutters regularly, and get annual roof inspections.
Yes—Tennessee’s humidity, storms, and seasonal changes make it a high-risk region for wood rot.
We’re Knoxville’s most trusted roofer with fast service, expert techs, and transparent pricing.
Litespeed Construction: Knoxville’s Trusted Roofing Experts
With 12+ years serving Knoxville and East Tennessee, Litespeed Construction brings:
- Licensed and Insured Roofers
- Same-Day Emergency Roof Repair
- Drone Roof Inspections
- Long-Term Warranties
Our team doesn’t just patch leaks—we replace rotten wood with precision and build roofs to last.
📞 Call (865) 297-3286 for a free inspection or quote!
