Re Felting a Shed Roof

Re felting a shed roof is a practical DIY project that extends the life of an outbuilding and protects its contents. This guide covers planning, material choices, and a step-by-step method to re-felt a shed roof efficiently and safely. It emphasizes common pitfalls, weather considerations, and long-term maintenance to ensure a durable, watertight result.

Why Re Felt A Shed Roof And When

Felt, or roofing felt, acts as an underlayment and moisture barrier. Re felting becomes necessary when the existing material is worn, torn, or has begun to lose its waterproofing. Signs include visible cracking, blistering, curling edges, or widespread granule loss from asphalt sheets. Proper felting improves leak resistance and can prevent rot in the roof deck. For many sheds, a high-quality asphalt or synthetic felt over a solid deck is sufficient for 15–20 years with proper maintenance.

Materials And Tools

Choosing the right materials is crucial for a lasting result. Consider climate, roof pitch, and deck condition. Common options include 15-lb or 30-lb asphalt roofing felt, and modern self-adhesive synthetic underlayment for steeper roofs.

• Roof felt: asphalt-based or synthetic underlayment, with self-adhesive options for easier installation
• Roofing nails or staples: corrosion-resistant, sized for felt and deck
• Starter strip: in a contrasting color to ensure clean edge seals
• Sealant or flashing tape: for edges, valleys, and penetrations
• Edge trim or closure strips: to seal lower edges and ridges
• Roofing cement or adhesive: if not using self-adhesive felt
• Chalk line, measuring tape, utility knife, razor blade
• Ladder, safety gear, gloves, eye protection
• Broom and chip brush: for surface preparation

Inspection And Preparation

Before removing the old felt, inspect the roof deck for damage. Look for soft spots, warped boards, rot, or signs of pests. Replace or repair damaged boards to provide a solid, even surface for the new felt. Clean debris, dust, and any granules from the old layer to ensure good adhesion and a smooth finish.

Check roof pitch and ventilation. A shed roof should shed water efficiently, and insufficient ventilation can cause moisture buildup under the felt. If the deck has knots or gaps, consider sealing or filling to create a uniform base. Ensure a dry, calm day for installation to avoid trapping moisture.

Removing Old Felt And Repairing The Deck

Start by removing the old felt from corners and edges. Use a utility knife to cut and lift layers, working from the bottom edge upward. Remove nails or staples and peel away any remaining material. As you uncover the deck, inspect for damage. Replace any soft or decayed sections with new boards, and allow repaired areas to dry completely before applying new felt.

After deck repair, sweep the surface thoroughly. A clean, dry surface ensures good adhesion and prevents dirt from creating bumps under the new felt. If there are minor gaps or fastener holes, seal them with appropriate sealant or filler and let cure before proceeding.

Underlayment Installation

Begin with a starter strip along the drip edge, which helps create clean, straight edges and reduces the likelihood of edge curl. Align the starter strip so the exposed edge will overhang the gutter or lower edge slightly, guiding water away from the shed. If using self-adhesive felt, peel back the release layer and firmly press the strip onto the deck, smoothing from the center outward to avoid air pockets.

Install subsequent rolls with an overlap of about 2–4 inches, depending on manufacturer recommendations. Use a chalk line to keep lines straight across the roof. Overlaps should ensure a continuous barrier against moisture, with horizontal laps aligned along the slope for proper shedding.

Edge, Valleys, And Penetrations

Seal edges with flashing tape or roof cement at eaves, rakes, and along any joints. Valleys and penetrations require careful sealing to prevent leaks. For sheds with skylights, vents, or chimneys, install additional flashing materials that bend and seal around irregular shapes. Maintain uniform laps and avoid creating creases that can trap moisture.

Securing The Felt And Finishing Touches

Fasten off the felt according to material type. For asphalt or synthetic felt, nails or staples should be driven at regular intervals to prevent billowing in wind. Ensure nails are flush and the heads sit slightly below the surface to avoid catching water. Use sealant on nail heads and joints as needed to reinforce waterproofing.

Inspect the entire roof after installation. Look for lifted edges, gaps, or any areas where the felt doesn’t lay flat. Apply additional adhesive or flashing where necessary, especially along the lower edges and at joints. If a ridge cap is used, ensure it is properly sealed for maximum protection against wind-driven rain.

Ventilation And Maintenance

Ventilation helps prevent condensation under the felt. Ensure there is adequate airflow around the shed, especially in humid climates. Periodic maintenance includes checking for lifted edges after storms, repairing compromised areas promptly, and removing debris that can trap moisture.

Routine maintenance tips include clearing gutters, inspecting for mold or mildew on exposed edges, and resealing any flashing or seals every few years. If the roof is in a high-stress environment or experiences frequent severe weather, consider upgrading to a higher-grade felt or integrating a lightweight metal flashing system for added durability.

Common Mistakes To Avoid

• Installing without a clean, dry surface
• Overlapping too little or too much, causing gaps or waste
• Not sealing edges and penetrations, leading to leaks
• Poor deck preparation, allowing soft spots to undermine the new felt
• Neglecting proper safety measures during ladder use and work at height

Maintenance Schedule And Longevity

With proper installation, shed roof felt can last 12–20 years depending on material and climate. Schedule regular checks after major weather events and seasonal changes. Early detection of bubbles, tears, or curling enables timely repairs that prevent larger leaks and deck damage.

Cost Considerations And Time Estimate

Material costs vary by type and region, but budgeting for both materials and tools is essential. A typical shed roof may require several rolls of felt, nails, and flashing. Labor time depends on roof size and complexity but expect a weekend project for a standard shed. DIY felting can save substantial costs compared to hiring a contractor, provided proper safety practices are observed.

Frequently Asked Questions

• Q: Can I use roofing cement alone to install felt? A: For some step-by-step installations, yes, but self-adhesive or underlayment felts provide better moisture resistance and ease of installation.
• Q: Do I need to remove all old material? A: Yes, to ensure a solid base and proper adhesion, unless the old layer is in good condition and compatible with the new felt.
• Q: How weather-dependent is this job? A: Choose a dry period with mild temperatures; rain or high humidity can compromise adhesion and curing.

Safety And Environmental Considerations

Wear gloves, eye protection, and non-slip footwear. Use ladders safely and secure the working area. Dispose of old materials responsibly, following local rules for construction waste. Proper disposal prevents environmental contamination and supports sustainable home improvement practices.