The presence of wet roofing felt during a re-roof project raises crucial questions about safety, durability, and long-term performance. This article explains why roofing over wet felt is generally discouraged, outlines how to assess moisture, and provides practical steps for a proper replacement that protects the roof structure and interior spaces. It covers common scenarios, moisture risks, and when a temporary overlay might be considered, with emphasis on long-term integrity.
Why Wet Felt Paper Is a Concern
Roofing felt acts as an underlayment, offering a secondary barrier against moisture and a surface for shingles to grip during installation. When felt is wet, its strength decreases, and its dimensional stability worsens. Wet felt can trap moisture in the roof deck, leading to rot, mold, and accelerated deterioration of plywood or OSB sheathing. Moreover, shingles installed over damp material may not seat properly, creating gaps and wind uplift vulnerabilities. The bottom line is that moisture in the underlayment undermines the roof’s long-term performance.
Assessing The Extent Of Moisture
Before deciding on a roofing strategy, conduct a careful moisture assessment. Visual cues include damp or darkened deck areas, musty odor, and visible water stains on interior ceilings near the attic. Use a moisture meter to measure the wood’s moisture content; readings above 15 percent typically indicate a need for caution and further inspection. Inspect roof framing for soft spots, cupping, or sagging. If any structural damage is found, professional evaluation is essential. Document findings for insurance and permitting if applicable.
Options When Roofers Encounter Wet Felt
In most cases, the recommended approach is to remove wet felt and replace with a dry, new underlayment. This secures a sound base for shingles, reduces future moisture risk, and preserves warranty terms. However, there are limited scenarios where roofing over existing underlayment or minor dampness might be considered, typically only as a temporary measure in controlled conditions. Any overlay decision should be made with caution and a clear plan for drying and replacement.
Primary Recommendation: Tear Off And Replace
Removing old shingles and underlayment allows full inspection of the deck, ensures dry surfaces, and supports proper ventilation. After removing the existing layers, replace deck boards if damaged, install new underlayment, and reattach flashing and drip edge. This method delivers the most durable and code-compliant result, particularly on aging roofs or those with visible moisture issues. It also reduces the risk of hidden rot that could appear after the new roof is installed.
Temporary Or Limited Overlays (When Absolutely Necessary)
In very specific circumstances, a temporary overlay might be considered if the deck is dry and in solid condition, and weather conditions are favorable to allow rapid completion. This approach is not a substitute for proper drying and replacement and is generally not advised for long-term maintenance. If used, ensure the existing felt is dry, the roof is properly ventilated, and a high-quality underlayment is installed over the existing layer to minimize moisture entrapment.
Step‑By‑Step: Safe And Correct Re-Roofing Over Wet Felt
If the decision is made to proceed with a tear-off or to manage damp conditions effectively, follow these steps to ensure a high-quality result and minimize moisture-related risks:
- Secure The Site: Protect the interior with tarps, cover landscaping, and set up fall protection for workers. Ensure the attic is ventilated to monitor moisture levels.
- Remove Damaged Materials: Strip existing shingles and underlayment. Examine the roof deck for rot, soft spots, and fastener pull-out. Replace any compromised boards with matching thickness and structural capacity.
- Dry The Deck: Allow the wood to dry completely before any new layering. If conditions require, use heaters or dehumidifiers in the attic to accelerate moisture removal while maintaining safe temperatures.
- Install A Fresh Underlayment: Use a high-quality, weather-rated underlayment appropriate for the climate. Ensure proper lapping, nailing patterns, and alignment at eaves and valleys to prevent moisture intrusion.
- Attach Proper Flashing: Replace or repair all flashing around chimneys, vents, skylights, and transitions. Use corrosion-resistant fasteners and sealants designed for the chosen roofing material.
- Install Roofing Material: Follow manufacturer guidelines for shingles, metal, or tile. Maintain appropriate ventilation and attic insulation to reduce future condensation.
- Inspect After Completion: Check for gaps, nail pop-throughs, and proper sealant application. Ensure water sheds properly at all valleys and edges.
Moisture Management And Ventilation
Ventilation is a critical factor in preventing moisture buildup beneath roofing materials. A well-ventilated roof assembly helps regulate temperature, reducing the risk of condensation and timber decay. In the attic, ensure soffit and ridge vents are clear and sized to promote continuous airflow. In colder climates, consider extra insulation to prevent warm indoor air from meeting cold roof decks, which can cause condensation on the underside of the roof felt.
Common Mistakes To Avoid
- Ignoring Dampness: Proceeding with a new roof without addressing damp or rot can trap moisture and shorten roof life.
- Inadequate Deck Repair: Failing to replace rotten sheathing creates a weak foundation for the new roof.
- Inconsistent Fastening: Skipping recommended nailing patterns or improper staple use can compromise wind resistance.
- Improper Overlays: Roofing over damp felt or damaged underlayment can void warranties and invite leaks.
Permits, Codes, And Warranty Implications
Most U.S. jurisdictions require building permits for re-roof projects, especially when structural work is involved. Inspections may verify deck integrity, underlayment installation, and ventilation adequacy. Many shingle and membrane warranties require a full tear-off and replacement of damaged decking to remain valid. Homeowners should verify local code requirements, obtain appropriate permits, and review manufacturer warranty terms before proceeding.
Key Takeaways For Homeowners
When faced with wet felt paper, the safest and most durable path is typically to remove the existing roofing system, dry the deck, and install a fresh underlayment and shingles. Thorough inspection for deck damage is essential, as is ensuring proper ventilation to mitigate future moisture problems. While temporary overlays may seem appealing, they do not offer the long-term protection of a properly executed tear-off and replacement.