Window Leaking — frame, glass

Use only checks that match the exact appliance or system and its official guide.

1. Check 1

   Map the first wet location after the next safe inspection: check the room-side glass, the space between panes, the sill or track, the frame edge, and the adjacent trim or wall without removing the sash or glass.

   Expected result: Moisture is only on the room-side glass, between panes, in the track, or on the frame/wall perimeter.

   Next step: Follow the matching branch rather than applying sealant everywhere. Photograph the location and note whether it appeared after rain, temperature change, or ordinary indoor activity.

   Why this matters

   Why: Room-side surface moisture is more consistent with condensation; moisture between panes suggests a sealed-glass-unit seal issue; track or perimeter water requires a drainage and water-entry trace.

2. Check 2

   Compare the event with weather and indoor conditions: note whether the moisture appears during high indoor humidity or temperature differences, or only after wind-driven rain, snow, or exterior washing.

   Expected result: Moisture forms without rain on the interior glass, or it appears at the frame or wall after precipitation and is concentrated on one side.

   Next step: For condensation, reduce indoor moisture and monitor the glass and frame. For rain-related perimeter water, inspect the sill, exterior joints, and areas above the window; do not assume the visible wet spot is the entry point.

   Why this matters

   Why: Andersen explains that interior condensation can form when indoor moisture meets cooler glass, while exterior water management depends on a continuous drainage path around the opening.

3. Check 3

   With the window closed and safe to reach, inspect the sill and track for dirt, paint, insect debris, or other material blocking the existing drainage or weep openings. Clear only loose surface debris with a soft brush or vacuum as permitted by the manufacturer's care instructions.

   Expected result: An existing sill drain or weep opening is visibly blocked, or water remains pooled in the track after the area is cleaned.

   Next step: Clean the accessible opening without enlarging it or sealing it. If water still remains, the opening is concealed, or the sill is damaged, stop and arrange window service rather than drilling or caulking the track.

   Why this matters

   Why: Some window systems are designed to let incidental water collect in the sill and drain outside; an obstruction can redirect that water toward the room.

4. Check 4

   Inspect the user-accessible frame and sash: verify that the window closes and locks fully, look for torn or compressed weatherstripping, cracked visible sealant, gaps, frame movement, and damage to the glass edge or glazing bead.

   Expected result: The lock does not pull the sash snug, weatherstripping is missing or damaged, sealant has cracks or voids, or the frame or glass is visibly damaged.

   Next step: Keep the opening protected from rain and use the manufacturer's approved repair or replacement path for a clearly damaged weatherstrip or exterior sealant. Escalate a damaged frame, glass, glazing bead, or recurring leak to a qualified window professional; do not force the sash or remove the glass.

   Why this matters

   Why: Andersen notes that a window that is not secured may leak and that weatherstripping or sealant can deteriorate; frame or glass damage can exceed a simple maintenance adjustment.

5. Check 5

   Trace above and beside the window before resealing the frame: inspect visible trim, siding or cladding joints, roof or gutter discharge, and the exterior head and side areas for a path that could carry water down to the frame.

   Expected result: Water staining or wetness begins above the window, at a side joint, or behind exterior cladding rather than at the glass or sash.

   Next step: Do not seal over the suspected drainage route or remove cladding as a casual test. Arrange a qualified window installer or building-envelope professional to inspect the flashing, rough opening, and adjacent wall assembly.

   Why this matters

   Why: Window openings interrupt the wall's water-resistive layer; flashing and the surrounding drainage plane must direct water out and away, so the window may only be the place where a higher leak becomes visible.

6. Check 6

   Assess the extent of damage before any repair: check the interior trim, drywall, sill, flooring, and frame for swelling, softness, discoloration, musty odor, or recurring dampness, and stop if water is near an outlet or other electrical component.

   Expected result: The frame or wall is soft or rotting, the leak is active or recurring, mold-like growth or a musty odor is present, or water has reached electrical components.

   Next step: Stop using or opening the window if doing so worsens the leak, move valuables away, and arrange qualified window/building-moisture service; use an electrician for affected electrical components. Do not conceal wet materials with paint or interior caulk.

   Why this matters

   Why: The problem may include hidden structural, moisture, or electrical damage and is no longer a simple visible weatherstrip or cleaning issue.