Skylights are a common feature of luxury home design, offering natural light and architectural elegance. However, if improperly installed, they can become a hidden source of water intrusion and costly damage.

This case study highlights GCI Consultants’ multi-phase building envelope investigation, expert diagnostics, and technical guidance for addressing skylight leak issues at a high-end Palm Beach residence. Following the discovery of water intrusion through newly installed sloped glazing systems, the owner engaged GCI to assess the source of leakage, evaluate the installation of multiple skylights, and provide recommendations that could be implemented collaboratively across contractors, subcontractors, manufacturers, and ownership representatives. Overall, it demonstrates our firm’s ability to manage complex technical challenges involving exterior glazing and roofing integration, while coordinating with multiple stakeholders to support an effective, phased repair process for long-term system performance.

The Challenge

Soon after a significant renovation, the property’s representatives reported visible water staining beneath several skylights throughout the home, specifically in the main atrium and conservatory units. Despite the use of HVHZ-approved systems, repeated interior damage indicated potential failure of the building envelope.

The issues were exacerbated by:

• Improper integration of skylight sills with the roofing system
• Visible gaps in mullion caps and sealants
• Complex parapet wall terminations
• Multiple parties involved, including contractors, subcontractors, and product manufacturers

GCI was engaged to identify the potential sources of leakage, provide observations and recommendations, and oversee corrective efforts that preserved both performance and aesthetic integrity.

Our Methodology / Approach

GCI’s role involved comprehensive building envelope consulting, diagnostic testing, documentation review, coordination, and oversight. The following key steps outline our process:

Document Review

We began by reviewing the Florida Product Approvals for the installed Series A and Series B skylight systems, evaluating the approved configurations and installation requirements specific to Florida’s High-Velocity Hurricane Zone (HVHZ). We compared these documents against on-site conditions to verify whether field installation methods appeared consistent with approved practices.

Initial Site Visit & Diagnostic Water Testing

Our first visit included baseline visual assessments of the skylight leaks and forensic water intrusion testing using AAMA 501.2 “Quality Assurance and Diagnostic Water Leakage Field Check of Installed Storefronts, Curtain Walls and Sloped Glazing Systems” and ASTM E1105 “Standard Test Method for Field Determination of Water Penetration of Installed Exterior Windows, Skylights, Doors, and Curtain Walls, by Uniform or Cyclic Static Air Pressure Difference” protocols. We utilized calibrated spray racks and controlled environmental conditions to isolate suspect joints and transitions, particularly around mullion caps, skylight curbs, and parapet interfaces. Testing revealed moisture penetration consistent with leakage at several horizontal mullion intersections and unsealed curb terminations.

Visual & Destructive Inspections

We performed detailed inspections of the skylights, parapet terminations, and roofing system. Where necessary, we directed removal of eave panels, sealants, and finish materials to inspect concealed construction conditions. These inspections revealed construction inconsistencies such as reversed flashing laps, discontinuous sealants, and limited anchorage detailing.

Drainage Pathway Evaluation

We assessed the skylight systems’ internal water management design including weep holes, internal gutters, and drainage channels. These components are intended to manage incidental water, but field conditions suggested these pathways may have been obstructed or improperly constructed, which may have contributed to the observed moisture intrusion.

Flashing and Curb Integration

Flashing and integration with adjacent roof systems were a significant concern. Industry standards from NRCA emphasize sequential, overlapping transitions. We observed conditions that were not consistent with typical sequencing practices recommended by industry guidance. These observations suggested areas where the integration approach may not have aligned with recommended practices.

Phased Site Visits & Skylight Leak Testing

Following the initial assessment of the skylight leaks, GCI returned to the home site at multiple stages to re-test specific skylights after interim remedial work had been performed. Each return visit included:

• Verification of previously observed conditions
• Testing newly repaired areas
• Advising on in-progress work and correcting deficiencies as needed

This phased involvement allowed us to track evolving site conditions, validate corrective work for the skylight leaks, and provide ongoing feedback to ensure that final remediation efforts aligned with expected standards.

Microbial Growth Risk & IAQ Concerns

Due to ongoing exposure and visible staining, the client requested insight into potential air quality issues. While GCI does not perform environmental sampling, we were happy to recommended a Certified Industrial Hygienist to assess microbial risks.

Local Coordination

As part of our professional services, we assisted the project team by helping respond to documentation requests from the Town of Palm Beach Building Department, including permit records and product approvals. We also participated in coordination among stakeholders — helping facilitate communication between contractors, subcontractors, ownership, and system representatives.

The Results

GCI’s phased evaluation and testing process contributed to identifying moisture migration pathways and tracking the effectiveness of ongoing repairs. The following outcomes were observed based on site conditions during our involvement:

• Leak Source Identification: Moisture penetration was observed in areas consistent with deficiencies at mullion caps, skylight-to-roof interfaces, and parapet flashing transitions.
• Repair Coordination: Our team monitored contractor efforts to reapply sealants, correct flashing details, and address field conditions previously identified. Where conditions warranted, we provided on-site direction and clarifications.
• Testing-Based Validation: Final water testing — conducted after remedial efforts — did not show visible leakage at the time of testing under standard procedures. While this supported the repair outcomes, long-term performance is dependent on maintenance and continued system integrity.
• Stakeholder Confidence: Through consistent communication, documentation, and phased oversight, GCI supported project teams in addressing the issue methodically while maintaining the residence’s performance and visual standards.

What We Learned about Skylight Leaks

This project reinforced several key considerations for high-end residential properties that incorporate skylights and sloped glazing systems:

• Installation sequencing matters: Proper integration of flashing, roofing membranes, and skylight frames is critical, particularly in complex assemblies.
• Product approvals don’t guarantee performance: Even HVHZ-rated systems can allow moisture intrusion if field installation deviates from approved conditions.
• Phased testing offers clearer insight: Multiple rounds of observation and diagnostic testing allow for real-time feedback and course correction — especially when remediation is evolving.
• Early expert involvement minimizes risk: Engaging an experienced building envelope consultant during design or early construction phases can reduce long-term issues and help preserve interior finishes and air quality

Need help solving a skylight leak? Contact GCI Consultants to speak with an expert and explore solutions that preserve your building’s value and performance.

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Frequently Asked Questions

Q: What causes skylights to leak in luxury homes?
A: Skylights often leak due to improper installation, missing or failed sealants, flashing defects, or poor integration with roofing materials. Wind-driven rain and poorly executed terminations can increase risk in homes like those in Palm Beach.

Q: How can you tell if a skylight is leaking or if the issue is elsewhere in the roof?
A: Water stains around skylight mullions or ceiling penetrations during rain events typically indicate skylight leaks. Diagnostic water testing is the most reliable way to isolate the source.

Q: Do skylights need special installation requirements in Florida’s HVHZ zones?
A: Yes, skylights installed in Florida’s HVHZ are subject to specialty code and performance criteria, including impact resistance and water infiltration standards.

Q: Can a skylight be repaired or does it need full replacement if it leaks?
A: Not all leaks require replacement. In this case, resealing joints, correcting flashing, and reinstalling key components supported system function without requiring full replacement.

Q: How long does a skylight water intrusion investigation take?
A: Our team can complete most investigation within 1-2 site visits and deliver a report within a few weeks. Remediation oversight may extend over several weeks depending on weather and project scope.

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Note: The insights in this case study are based on project-specific observations and industry experience. Applicability may vary depending on building type, system design, and site conditions. GCI’s recommendations were based on best practices and observed conditions at the time of site visits. They do not constitute certification, warranty, or future performance prediction of any building product or system. All our findings are based on site-specific conditions observed at the time of inspection. Testing and observations were conducted in accordance with industry protocols but do not represent a guarantee or certification of system performance.