Adding a skylight or sun tunnel can transform dark areas in a home, but proper installation is critical to prevent leaks—especially in Oregon’s rainy climate. Whether you’re a homeowner, contractor, or skilled DIYer, understanding the steps and key decision points is essential for long-lasting, watertight results.
Choosing Between Skylights and Sun Tunnels
Both skylights and sun tunnels bring natural light indoors, but the right choice depends on your goals and roof structure:
- Skylights are larger and offer outdoor views. They work best in spaces with direct roof access, like attics, vaulted ceilings, or rooms directly under the roof deck.
- Sun tunnels (also called tubular skylights) use a reflective tube to channel light, making them ideal for hallways, closets, or bathrooms where structural framing limits skylight size.
For Oregon homes with complex rooflines or frequent rain, sun tunnels can be easier to seal due to their smaller footprint, but both types require careful flashing and sealing.
Leak-Free Installation Essentials
The main cause of leaks around skylights and sun tunnels is improper installation. Here’s what matters most:
1. Product Selection
- Flashed Kits: Use units with integrated flashing designed for your roof material (asphalt, metal, etc.). Avoid generic or undersized flashing.
- Double-Paned and Curb-Mounted Options: In regions like western Oregon, double-paned glass and curb-mounted skylights provide better protection against condensation and leaks.
2. Location Matters
- Avoid valleys, hips, and low-slope roof areas where water collects or drains slowly.
- Place units at least a few feet from roof edges to minimize wind-driven rain exposure.
3. Preparation and Framing
- Mark and cut carefully: Use a framing square and measure twice before cutting roof sheathing. Damaged or overcut holes are harder to seal.
- Frame the opening: Properly frame the opening to support the skylight or sun tunnel and provide a solid nailing surface for flashing.
4. Flashing and Waterproofing
- Install underlayment (ice and water shield) at least 12 inches around the opening—especially important in Oregon’s wet climate.
- Follow manufacturer’s flashing sequence: Typically, this means step flashing layered with shingles, counterflashing, and sealant at all joints.
- Ensure shingle overlap: Always weave new shingles over step flashing, not under.
- Seal, but don’t overdo it: Use high-quality roofing sealant at vulnerable points, but don’t rely on caulking alone to keep out water.
Common Mistakes That Cause Leaks
- Skipping the underlayment: Not using a waterproof membrane under the flashing leaves a weak spot for wind-driven rain.
- Improper shingle integration: Flashing that sits on top of shingles, rather than woven between, can channel water inside.
- Over-tightening fasteners: This can deform the skylight flange or flashing, preventing a tight seal.
- Ignoring roof slope: Installing skylights on low-slope or flat roofs without proper curb height and flashing increases risk of pooling and leaks.
- DIY shortcuts: Using caulk instead of step flashing or skipping recommended layers often leads to future leaks, especially in persistent rain.
DIY Versus Contractor Installation
While skilled DIYers with carpentry and roofing experience can install sun tunnels or skylights, most leaks occur from inexperience or skipped steps. Consider:
- Complex roofs: If your home has a steep pitch, multiple layers of shingles, or difficult access, professional installation is safer and more reliable.
- Warranty considerations: Many skylight and sun tunnel products require professional installation for warranty coverage.
- Existing roof condition: Older or damaged roofs may need repairs before installation. A contractor can assess and address these issues.
For small, single-story homes with accessible attic spaces and standard roof pitches, a detail-oriented DIYer may successfully install a sun tunnel. Skylight installs, especially on second stories or complex roofs, are usually best left to experienced contractors.
After Installation: Maintenance and Inspection
Even a perfect installation requires periodic checks. To avoid leaks over time:
- Inspect around the skylight or sun tunnel after major storms for signs of moisture or staining on the ceiling.
- Check exterior flashing annually for cracks, lifted shingles, or sealant failures.
- Keep the roof clear of debris that can trap moisture or ice around the installation.
- Re-seal joints with compatible roofing sealant as needed, especially after several years of weather exposure.
Quick Checklist for Leak-Free Skylight and Sun Tunnel Installs
- Choose products with proper flashing kits compatible with your roof type.
- Place units away from valleys and low points on the roof.
- Use waterproof underlayment around the opening.
- Follow the manufacturer’s flashing sequence exactly—don’t skip steps or layer out of order.
- For complex or steep roofs, hire an experienced contractor.
- Inspect annually and after heavy storms for any signs of leaks.
With careful planning, correct flashing, and regular maintenance, skylights and sun tunnels can provide beautiful, natural light for years—without the worry of leaks, even in Oregon’s challenging climate.