Skylight
What is Skylight?
A skylight is a transparent or translucent window installed in the roof to allow natural light into the building interior. From an inspection standpoint, skylights represent significant potential leak points. The skylight-to-roof intersection requires an integrated flashing system that creates a watertight seal while allowing for thermal expansion. Key inspection points include the condition of flashing around all sides, integrity of the glazing seal (look for condensation between panes indicating seal failure), cracking in the dome or glass, and any visible gaps or deteriorated sealant. Fixed skylights are simpler than operable units, which have additional mechanisms that can fail. Curb-mounted skylights sit on a raised frame (curb) and are easier to flash than deck-mounted units that sit flush with the roof plane. Skylight leaks often appear as staining on interior ceilings or walls near the unit.
How to Identify Skylight
Understanding skylight types and components:
Skylight Types:
- Fixed skylights - Non-opening, simpler design, fewer failure points
- Venting/operable skylights - Open for ventilation, more complex mechanisms
- Tubular skylights - Small dome with reflective tube to interior, minimal roof penetration
- Roof windows - Larger units designed for egress or regular access
Mounting Styles:
Glazing Types:
- Acrylic dome - Economical, may yellow with age
- Polycarbonate - Impact-resistant, good for hail-prone areas
- Tempered glass - Flat profile, excellent clarity, heavier
- Double/triple pane - Insulated glass units with gas fill
Key Components:
- Frame/curb structure
- Glazing (dome or glass)
- Flashing system (step, apron, counter)
- Weep holes for condensation drainage
- Opening mechanism (if operable)
- Screens and blinds (if equipped)
Why Inspectors Look for Skylight
Skylights are common leak sources requiring careful inspection:
Skylights represent significant roof penetrations with complex flashing requirements. They're among the most common sources of roof leaks. Age, thermal movement, and sealant deterioration all contribute to skylight failures. Proper assessment helps identify issues before water damage occurs.
Documentation Requirements:
- Overall photos showing skylight location and condition
- Close-ups of flashing on all four sides
- Photos of glazing condition (cracks, clouding, seal failure)
- Documentation of sealant condition around frame
- Evidence of condensation between panes (seal failure)
- Interior photos if ceiling staining suggests leaks
Common Issues Found:
- Flashing failure - Gaps, lifted flashing, sealant deterioration
- Seal failure - Condensation between panes, foggy appearance
- Glazing damage - Cracks, yellowing, hazing
- Frame deterioration - Rotted wood curb, corroded metal frame
- Sealant failure - Cracked or missing caulk at joints
- Operating mechanism - Stuck, broken, or leaking when open
Skylight leaks often appear as staining on interior ceilings or walls near the unit. Leaks may only occur during certain conditions (wind-driven rain, ice dam backup, heavy rain).
Common Misidentifications
Skylight assessment requires checking multiple potential failure points:
Inspector Errors:
Installation Errors:
What Skylight Indicates
Skylight failures cause interior water damage and energy loss:
If Not Addressed:
- Water intrusion causes ceiling/wall damage below skylight
- Rot develops in wood curb structure
- Mold growth from persistent moisture
- Frame deterioration leads to structural failure
- Energy efficiency decreases with failed seals
- Operating mechanisms fail completely
Failure Progression:
- Stage 1 - Sealant deterioration, minor water entry during heavy rain
- Stage 2 - Flashing gaps develop, leaks more frequent
- Stage 3 - Frame damage, glazing seal failure, condensation
- Stage 4 - Structural failure of curb, major water intrusion
Storm damage to skylights (hail cracking glazing, wind damage to flashing) is typically covered. Seal failure and age-related deterioration are not covered—these are maintenance issues. Water damage resulting from sudden storm damage may be covered, while damage from gradual deterioration is typically excluded.
Failed glazing seals reduce insulation value significantly. Condensation between panes indicates gas fill has escaped and insulating properties are compromised. Old single-pane skylights may account for significant energy loss.
Repair and Treatment Options
Skylight repairs range from resealing to complete replacement:
Repair Methods:
Repair vs. Replace Considerations:
- Age 10-15+ years - Consider replacement for efficiency and warranty
- Seal failure - Reglazing possible, but replacement often better value
- Curb damage - May require replacement with curb-mounted style
- Multiple issues - Combined problems favor replacement
- Reroofing planned - Ideal time to replace older skylights
Cost Considerations:
When reroofing, replace skylights over 15 years old. New roofing materials integrate better with new skylights. Old flashing systems may not work with new roofing, making replacement more practical than reflashing.
Prevention and Maintenance
Regular maintenance extends skylight life and prevents leaks:
Maintenance Tips:
Installation Best Practices:
When to Seek Professional Help:
- Visible condensation between panes
- Recurring leaks despite DIY sealing
- Cracks in glazing
- Operating mechanism problems
- Water staining on interior surfaces
- During reroofing projects
What to Avoid:
- Using household caulk instead of roofing sealant
- Ignoring condensation as cosmetic issue
- Walking directly on glazing
- Pressure washing skylight area
- Delaying repairs until major water damage occurs
How Roof Report Pro Detects Skylight
Roof Report Pro's AI evaluates skylight condition and potential issues:
Image Analysis Capabilities:
- Skylight identification - Recognizes skylights in roof photos
- Type classification - Identifies curb-mounted vs. deck-mounted, fixed vs. operable
- Condition assessment - Evaluates visible condition of glazing, frame, and flashing
- Flashing evaluation - Checks visible flashing components
- Damage detection - Identifies cracks, debris, or obvious damage
Condition Categories:
- Good condition - Clear glazing, intact flashing, no visible issues
- Fair condition - Minor wear, aging sealant, monitor recommended
- Needs attention - Visible damage, deterioration, or potential leak sources
- Failed/damaged - Cracks, missing components, active leak indicators
The AI-generated report documents each skylight's location, type, and visible condition. Given skylights' reputation as leak sources, the report notes any concerns and recommends interior inspection if ceiling staining is possible.
Skylight seal failure (condensation between panes) may not be visible in all lighting conditions. Interior inspection provides additional information about skylight performance and potential leak history.
Frequently Asked Questions
Related Terms
Flashing
Metal or other waterproof material installed at roof intersections and penetrations to direct water away and prevent leaks.
Roof Deck (Sheathing)
The structural base layer of a roof, typically plywood or OSB, to which underlayment and roofing materials are attached.