How to Felt a Garage Roof

Felling a garage roof with roofing felt provides a durable water barrier that protects the structure and its contents. This guide walks through selecting the right felt, preparing the surface, applying underlayment, and finishing touches. With clear steps, homeowners can achieve a professional-looking result that improves weather resistance and extends the life of the garage roof.

Preparation And Planning

Before starting, inspect the roof for damage and repair any loose boards or shingles. Measure the area to estimate the amount of felt, nails, and adhesive needed. Choose the correct type of felt: standard asphalt-saturated felt is common for flat or low-slope roofs, while self-adhesive or torch-down options suit steeper pitches and advanced repairs. Ensure proper ventilation and schedule work for dry weather to prevent moisture trapping during installation. Clear the work area and set up a sturdy ladder and fall-protection plan if working from height.

Materials And Tools

Selecting the right materials is essential for a long-lasting install. Typical supplies include:

• Roofing felt (asphalt-saturated or self-adhesive)
• Roofing nails or staples (galvanized or stainless steel)
• Underlayment adhesive or roofing cement
• Roofing cap nails or plastic caps
• Utility knife or shears
• Tape measure and chalk line
• Hammer or nail gun
• Roofing tar or sealant for seams
• Caulk gun and roofing sealant (optional for edging)
• Safety gear: gloves, eye protection, non-slip shoes

Choose 15-pound or 30-pound asphalt-saturated felt based on climate and roof type. For self-adhesive felt, ensure the surface is clean, dry, and free of dirt or oil for good adhesion. If the roof pitch is greater than 4:12, confirm local code requirements and consider professional help for extended overhangs or flashings.

Safety Considerations

Roof work carries fall and material hazards. Use a stable ladder with a helper to hold it, wear a harness on steep roofs, and keep signaling devices handy. Work on dry days to prevent slips from wet surfaces. Use rubber-soled shoes for better traction, and handle rolls carefully to avoid back strain. Keep tools tethered when working near edges to prevent drops. If the roof carries heavy loads, limit foot traffic to prevent damage to existing roofing materials.

Step-By-Step Installation Guide

The following steps describe a common approach for installing asphalt-saturated felt on a garage roof with a moderate slope:

1. Clean the surface: Remove debris, dust, and loose nails. Inspect the sheathing and repair any warped boards.
2. Install starter strip: Begin at the eave line with a starter strip of felt or pre-cut starter rolls. Ensure the strip overhangs the edge slightly to shed water evenly.
3. Lay the first course: Unroll felt along the eave, aligning it with the edge. Allow the lower edge to hang slightly past the drip edge. If using self-adhesive felt, peel back a portion of the release film and press firmly as you go to prevent air pockets.
4. Secure with fasteners: For standard felt, use galvanized roofing nails or staples every 8 to 12 inches along the top edge, avoiding over-tightening that could tear the material. Space nails evenly to prevent sagging.
5. Overlap and seal seams: Roll out successive courses with a 19 to 24 cm (7.5 to 9.5 inch) horizontal overlap for felt underlayment. For self-adhesive felt, press each course firmly to seal seams; apply roofing cement along exposed edges for additional waterproofing.
6. Seal edge details: Install felt up the sloped sides and around penetrations with extra care, ensuring a tight seal at the edges and corners. Use sealant or caulk where necessary, especially along valleys or where water can pool.
7. Inspect for air pockets: Run a hand along the felt to detect air pockets or raised areas. Press down and re-seal any loose spots. Trim excess felt at the ridge line for a clean finish.
8. Finish with a drip edge: Install a metal drip edge along the eave to guide water away from the fascia. Tape or seal where needed to prevent water intrusion at the fascia board.

Common Issues And How To Fix Them

Even careful installation can encounter issues. Common problems include curling edges, air pockets, or uneven seams. To fix:

• Curling edges: Press flat and re-secure with nails or adhesives; avoid over-tensioning during installation, especially in heat.
• Air pockets: Puncture gently and reseal with roofing cement; ensure proper overlap and smooth out air before securing.
• Seam leaks: Re-press seams firmly, add extra sealant or cement, and verify the underlying sheathing is intact and dry.
• Damage from moisture: If water has penetrated, inspect for compromised underlayment and replace sections as needed to maintain a waterproof barrier.

Maintenance, Longevity, And Troubleshooting

Proper maintenance extends the life of garage roof felt. Keys include regular inspections after severe weather, cleaning gutters to prevent water backup, and replacing damaged sections promptly. Self-adhesive felts tend to seal well but may lose adhesive in extreme heat; periodically re-press and reseal if you notice lifting edges. For roofs with high exposure or atypical climate, consider a second layer of underlayment or upgrading to advanced synthetic underlayment for enhanced durability.

Cost And Time Considerations

Costs vary by material, roof size, and regional labor rates. Expect to pay for felt rolls, nails, sealants, and basic tools if doing it yourself. A small garage roof often takes a weekend for a thorough job, factoring in dry weather windows and safety time. Hiring a professional can provide quicker results and ensure code-compliant installation, especially for steeper pitches or roofs with complex flashings.

Tips For A Pro-Like Finish

To achieve a professional look and lasting performance, follow these tips:

• Work in mild temperatures to prevent the felt from tearing or becoming brittle.
• Keep rolls flat and unrolled along the roof path to avoid wrinkles.
• Align edges carefully for a uniform appearance and better water shedding.
• Ensure proper overlap: standard practice is a 19 to 24 cm (7.5 to 9.5 inch) horizontal overlap and 15 cm (6 inch) vertical overlap for additional coverage at seams.