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Roof Skylights: Understanding and Preventing Rot

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Written by Nathan Toothman
Updated over 6 months ago

Skylights are a popular feature in homes, offering natural light and a unique design element. However, like any roof component, skylights are vulnerable to issues if not properly maintained. One significant problem homeowners may encounter is rot—particularly in the wooden frames or surrounding roofing materials. Rot can lead to structural damage, reduced energy efficiency, and potential health hazards if left unaddressed.

Causes of Rot Around Skylights

1. Persistent Moisture

Moisture is the primary culprit of rot. If a skylight is not properly sealed or if leaks develop over time, water can accumulate in and around the frame or roof structure. This damp environment creates the perfect conditions for rot to develop.

2. Improper Installation

A poorly installed skylight can leave gaps or weak points where water infiltrates. Flashing that isn’t properly secured or sealed is a common source of moisture intrusion.

3. Aging Materials

Over time, the materials surrounding a skylight—such as the frame, flashing, or sealants—can deteriorate, becoming less effective at keeping water out. Older skylights with wooden frames are particularly prone to rot if not regularly maintained.

4. Condensation

In humid environments or during colder seasons, condensation can form on the interior of a skylight. If this moisture is not managed, it can seep into wooden components and lead to rot.

5. Clogged Roof Drainage

Debris like leaves and dirt can block proper water drainage around a skylight, causing water to pool and increasing the likelihood of rot in nearby materials.

Signs of Rot Around Skylights

Discoloration or Staining: Darkened or discolored wood around the skylight frame is an early indicator of rot.

Soft or Spongy Wood: Pressing on the wood and finding it soft or crumbly is a clear sign of rot.

Mold or Mildew Growth: The presence of mold around the skylight often signals excess moisture and potential rot.

Warping or Cracks: Warped wooden frames or cracking in the surrounding materials could indicate structural damage from rot.

Persistent Musty Smell: A damp or musty odor near the skylight area may be a sign of hidden rot.

Preventing Rot Around Skylights

1. Proper Installation

Ensure your skylight is installed by a professional who understands the importance of sealing and flashing. Proper installation minimizes the risk of water infiltration.

2. Use Rot-Resistant Materials

Opt for skylights made with rot-resistant materials, such as aluminum or vinyl frames. These materials are less susceptible to moisture damage than wood.

3. Regular Inspections

Inspect your skylight and the surrounding area at least twice a year for signs of moisture damage, gaps, or deterioration. Pay close attention after heavy rainstorms or snowmelt.

4. Maintain Roof Drainage

Keep your roof and gutters clear of debris to prevent water pooling around the skylight. Installing a roof drainage system can further protect against water accumulation.

5. Seal and Protect Wooden Frames

For skylights with wooden frames, apply a water-resistant sealant to protect against moisture. Reapply this sealant periodically to maintain its effectiveness.

6. Manage Indoor Humidity

Use ventilation systems, dehumidifiers, or exhaust fans to reduce humidity in rooms with skylights, especially bathrooms or kitchens.

Repairing Rot Around Skylights

If you notice rot around your skylight, take action immediately to prevent further damage:

1. Remove Affected Materials

Carefully remove any rotted wood or damaged roofing materials. Be thorough to ensure no hidden rot is left behind.

2. Replace with New Materials

Replace rotted wood with treated lumber or rot-resistant materials like vinyl or metal. Damaged flashing or shingles around the skylight should also be replaced.

3. Seal and Protect

Apply a high-quality sealant to all joints, edges, and replacement materials to ensure a watertight finish.

4. Address Underlying Issues

Identify and fix the root cause of the rot, such as leaks, poor ventilation, or clogged drainage systems.

When to Call a Professional

While minor rot can sometimes be repaired by a handy homeowner, severe cases or rot affecting structural components require professional attention. A roofing contractor or skylight specialist can assess the extent of the damage and ensure repairs are completed safely and effectively.

Conclusion

Rot around roof skylights is a serious issue that can compromise the integrity of your home and lead to costly repairs. By understanding the causes of rot, performing regular maintenance, and addressing problems promptly, you can protect your skylights and the surrounding roof structure. With proper care, your skylight can remain a bright, beautiful feature in your home for years to come.

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