Commercial storefront water intrusion follows predictable paths. Before any repair work begins, the source must be isolated — guessing and applying caulk at every visible joint is expensive and rarely resolves the problem. This guide covers the diagnostic sequence (visual inspection, controlled water testing per ASTM E1105, and infrared thermography), the five most common storefront intrusion paths, and the remediation steps for each. Intended for building owners, property managers, and general contractors managing warranty or maintenance claims.
The most common error in commercial storefront water intrusion response is applying new sealant at visible cracks without verifying those cracks are the actual source. Storefront systems have multiple potential pathways; water entering at one location may travel through extrusion channels, behind substrates, or along framing members before appearing at the interior in a different location entirely. This source migration is responsible for most failed repair attempts.
A systematic diagnostic sequence eliminates this problem. The three tools — visual inspection, controlled water testing, and infrared thermography — are used in sequence from least to most resource-intensive, with each step narrowing the possible source.
Visual inspection is performed in both dry and wet conditions and covers interior and exterior faces of the system. Key items to examine:
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, is the primary field water test method for commercial glazing systems. It applies water at a controlled rate while maintaining a static air pressure differential across the system, simulating the combined effect of rain and wind pressure.
A calibrated pressure chamber is mounted against the interior face of the test area. A calibrated spray rack is positioned on the exterior at 5 gallons per hour per square foot. The chamber creates a negative pressure differential (typically 6.24 psf or as specified in the project specification) while the spray rack applies water. The system is observed for 15 minutes for any water penetration at the interior.
Before mobilizing E1105 equipment, a controlled hose test can isolate the general area of leakage. The hose test uses a calibrated nozzle at low flow rate, systematically wetting individual sections of the frame from bottom to top. An observer inside reports when water appears. The section being wetted when interior leakage occurs identifies the approximate source zone for more precise E1105 testing.
Infrared thermography is used when the diagnostic source is suspected to be within the wall assembly — behind sheathing, in insulation, or at substrate interfaces — and visible and water testing have not conclusively isolated the entry point. Infrared cameras detect temperature differentials between wet and dry materials. Moisture trapped in wall cavities retains heat differently than dry materials and appears as a distinct thermal pattern in an IR image.
Conditions for effective IR thermography include a temperature differential of at least 10°F between interior and exterior, and recent moisture introduction (active leakage or within 24–48 hours of a rain event or hose test). IR surveys are most effective in Florida during morning hours when nighttime cooling has established a temperature gradient.
IR results identify moisture accumulation zones, not necessarily entry points. Combine IR findings with controlled hose test results to confirm both where water is accumulating and where it is entering.
The sealant joint between the storefront frame and the surrounding construction (concrete, CMU, steel, or GFRC) is the most common source of water intrusion in aging systems. Sealant has a finite service life — typically 7–12 years for quality silicone in Florida's UV and thermal environment. Failure modes include adhesion failure at one or both surfaces (sealant remains elastic but lifts from substrate), cohesive failure (cracking through the sealant body), and substrate movement beyond the joint's designed movement capacity. The entire perimeter joint must be replaced, not patched — patching over failed sealant adds mass without restoring adhesion.
Wet-glazed storefront systems seal the glass to the frame inside the glazing pocket with a structural or weather sealant. This wet seal can fail through UV degradation (exposure at the exposed bead face), glass coating incompatibility (some low-E coatings require specific sealant types), or improper original installation (insufficient bite, voids, tooling failure). Water penetrating the glazing pocket typically appears at the interior sill area. Repair requires removing the failed wet seal, cleaning glazing pocket surfaces, and applying a compatible replacement sealant with proper tooling and joint geometry.
Storefront sill extrusions are designed with weep slots or weep baffles that drain water collected inside the frame cavity to the exterior. When weeps are blocked by construction debris, paint overspray, bird debris, or caulk applied during a previous repair attempt, water accumulates in the sill cavity and overflows to the interior. Clearing blocked weeps is a straightforward maintenance task, but if weeps have been blocked for an extended period, corrosion of the sill extrusion or adjacent steel may have occurred, requiring more extensive remediation.
The transition at the frame head — where the storefront frame meets the wall assembly above — requires positive drainage away from the frame and integration with the wall waterproofing or EIFS system above. Head flashing failures occur when the flashing was omitted, when laps are insufficient, when flashing material has torn or separated, or when caulk was relied upon as the primary waterproofing at this location rather than a physical flashing membrane. Water entering at the head runs down inside the wall and may appear at the sill extrusion or at the frame perimeter, mimicking other failure modes. This source is frequently misdiagnosed without systematic testing.
Exposed anchor fasteners, anchor covers, and anchor pocket locations at the frame perimeter are potential water entry paths when the original sealant around them degrades or was improperly applied. In HVHZ systems, the anchor locations are defined by the NOA and may penetrate into the wall cavity at multiple points around the frame perimeter. Water tracking along fasteners into wall cavities can cause corrosion in framing members, substrate damage, and interior leakage that appears remote from the actual entry point. Each exposed anchor location in the perimeter sealant zone requires the same sealant maintenance as the perimeter joint generally.
Once the source has been isolated by diagnostic testing, remediation follows a defined sequence for each failure type.
Head flashing repair typically requires access to the wall assembly above the frame head, coordination with the roofing or waterproofing contractor, and integration with the existing waterproofing membrane. This is not a glazing-only repair; the glazing contractor typically coordinates with the GC or waterproofing subcontractor. The glazing scope covers the frame head reglet, sealant to the flashing, and any frame-side components. The flashing itself is typically a separate trade scope.
Water intrusion repair on commercial systems should be documented with:
For warranty claims on systems still under original warranty, the original glazing contractor and system manufacturer must be notified before any repair work is undertaken. Unauthorized repair by a third party may void the original warranty. ACG coordinates warranty claim documentation when engaged on repair work originally installed by others.
ASTM E1105 is the Standard Test Method for Field Determination of Water Penetration of Installed Exterior Windows, Skylights, Doors, and Curtain Walls. It applies water at a calibrated rate while maintaining a static air pressure differential, simulating wind-driven rain. It is used both at installation acceptance and during diagnostic investigation of reported leaks.
The five most common sources: (1) perimeter sealant failure between the frame and surrounding construction; (2) glazing pocket sealant failure at the glass-to-frame interface; (3) blocked weep slots in the sill extrusion; (4) head flashing failure or omission at the frame-to-wall transition; (5) fastener corrosion or missing sealant at anchor penetration points.
The diagnostic sequence is: visual inspection of sealant, gaskets, weeps, and flashing; controlled hose test or ASTM E1105 to isolate the section producing leakage under simulated rain; and infrared thermography when the source may be within the wall assembly. Work from the bottom of the system upward — sill and weeps first.
Yes. Perimeter sealant replacement does not require frame removal. The process is: remove all existing failed sealant, clean joint surfaces, install backer rod, apply primer if required, apply new compatible sealant, tool, and post-repair water test. Do not apply new sealant over old — full removal is required for effective repair.
Annual inspection is recommended, plus inspection after major storm events. Florida's pollen, humidity, and debris load accelerates weep obstruction. Blocked weeps are a leading cause of sill-area leaks that are misdiagnosed as perimeter sealant failures.
Yes. American Commercial Glass (FL CGC #1531993) provides diagnostic services and remediation on commercial storefront, curtainwall, and window wall systems across Florida. Diagnostics include visual inspection, controlled hose testing, and infrared coordination. Written scope and root-cause identification precede all repair work.