Properly installed roof flashing is crucial for maintaining a watertight seal and protecting your roof from water intrusion. However, when flashing is improperly secured by nailing it through shingles, it can compromise the roof’s integrity and lead to serious issues over time.
Why Nailing Flashing Through Shingles Is a Problem
Creates Entry Points for Water
Nails driven through shingles create small holes, which are vulnerable to water infiltration.
Over time, nails can loosen, leaving gaps that allow water to seep into the roof deck.
2. Weakens the Shingles
The pressure of nails can crack or damage shingles, reducing their effectiveness and lifespan.
3. Difficult to Seal Properly
Even when sealed with roofing adhesive or caulk, nails through shingles are a weak point in the roof system, especially under harsh weather conditions.
4. Limits Flexibility
Roofs naturally expand and contract due to temperature changes. Nails through shingles can restrict movement, increasing the risk of cracks and damage.
5. Voids Warranty
Many roofing warranties specify proper flashing installation methods. Nailing through shingles can void these warranties, leaving homeowners unprotected.
Correct Flashing Installation Practices
Under the Shingles
Flashing should be installed under the shingles, not nailed directly to their surface.
This ensures a seamless transition that channels water away from vulnerable areas.
2. Step Flashing for Joints
Use step flashing at joints or intersections, such as where a roof meets a wall or chimney. Each piece of step flashing should overlap and integrate with the shingles for optimal protection.
3. Secure Flashing to Roof Deck or Sidewall
Nails should secure flashing to the roof deck or sidewall, not through the shingles themselves.
4. Sealant Use
Apply a high-quality roofing sealant around the edges of the flashing to create a watertight barrier without compromising the shingles.
Signs of Problems with Nailed-Through Flashing
Water Leaks: Visible water stains on ceilings or walls near the area where flashing is installed.
Loose or Missing Nails: Exposed or popped nails can indicate flashing installed through shingles.
Warped or Damaged Shingles: Cracked or misshapen shingles around the flashing area.
Rust or Corrosion: Nails exposed to moisture can rust, weakening the seal further.
How to Fix Improperly Installed Flashing
Inspect the Affected Area
Identify where flashing is nailed through shingles and assess the extent of the damage.
2. Remove Improper Flashing
Carefully remove the nails and flashing, taking care not to damage surrounding shingles.
3. Replace with Proper Flashing
Install step flashing, counter-flashing, or continuous flashing as appropriate for the area.
Ensure the new flashing is placed under the shingles and properly secured to the roof deck or wall.
4. Seal Nail Holes
Fill any nail holes in the shingles with roofing sealant to prevent water intrusion.
5. Consult a Professional
For complex repairs or areas prone to leaks, hire a roofing contractor to ensure proper installation and sealing.
Preventing Flashing Installation Errors
Hire Experienced Professionals: Work with certified roofers who follow industry best practices.
Inspect After Installation: Verify that flashing is installed under the shingles and properly secured.
Use Quality Materials: High-grade flashing and sealants reduce the likelihood of future issues.
Follow Manufacturer Guidelines: Ensure installation complies with roofing material specifications to maintain warranties.
The Importance of Proper Flashing Installation
Improperly installed flashing, especially when nailed through shingles, undermines the roof’s ability to protect against water damage. Over time, this can lead to:
Expensive repairs due to leaks and structural damage
Mold and mildew growth from persistent moisture
Reduced roof lifespan and compromised performance
Final Thoughts
Nailing flashing through shingles is a common but avoidable roofing mistake. Ensuring that flashing is installed correctly—beneath the shingles and securely fastened—protects your home from water damage and extends the life of your roof. If you suspect improper flashing installation, take prompt action to address the issue and consult a professional roofer to ensure a long-lasting solution.