Building doors and windows are a crucial part of the building envelope. Once air or water leakage occurs, it directly affects indoor comfort and may cause secondary problems such as wall mold and profile corrosion. Many projects often encounter water seepage and air drafts after the doors and windows are put into use. Below is a science-based overview of common causes and corresponding solutions.
I. Main Causes of Window and Door Water Leakage
1. Aging & Improper Sealant Application
Exterior frame-wall joint sealant cracks, shrinks, or chalks over time. Poor surface prep before application causes weak bonding, letting rainwater seep indoors.
2. Clogged or Poor Drainage Design
Drainage holes in profiles clog with debris, causing overflow. Lack of air pressure equalization holes allows wind-driven backflow into the cavity.
3. Wrong Installation Slope & Filling Gaps
No outward tilt prevents proper drainage. Voids in frame-wall filler (e.g., PU foam) create hidden seepage channels-hard to detect and trace.
4. Glass-to-Frame Seal Failure
Aged or detached seals (sealant/rubber strips) between glass and frame let rainwater enter the cavity and seep indoors.
II. Main Causes of Air Leakage in Doors and Windows
1. Aging and Shrinkage of Rubber Seals
Rubber seals are the core component blocking air circulation. Under long-term alternating high and low temperatures, the seals harden and lose elasticity, failing to tightly fit the profile when closed. This allows hot and cold air exchange, creating drafts that are especially noticeable in winter and summer.
2. Wear of Hardware Accessories, Increasing Closing Gaps
After repeated opening and closing, hardware components such as hinges, locking points, and striker plates become loose or worn. The door/window sash can no longer press tightly against the frame, creating gaps between the sash and frame through which outdoor air infiltrates, causing air leakage.
3. Poor Sealing at Profile Joints
The sealing at corner joints of profiles is inadequate, leaving tiny gaps. Alternatively, insufficient processing precision results in oversized joint gaps, allowing outdoor air to continuously penetrate through these seams.
III. Corresponding Solutions
·Water Leakage Solutions
Remove aged and failed exterior weather-resistant sealant, sand and clean the joint substrate, and reapply weather-resistant silicone sealant after it is completely dry. Regularly clear the profile drainage holes to ensure smooth drainage; install air pressure equalization holes if necessary to prevent rainwater backflow during strong winds.
During installation, strictly control the window frame leveling and reserve an outward drainage slope. Fill gaps between the frame and wall with polyurethane foam (PU foam) compactly, then seal the exterior with weather-resistant sealant.
Inspect the sealant or rubber strips between the glass and frame, and replace aged, cracked, or missing sealing components to block rainwater infiltration from the glass area.
·Air Leakage Solutions
Conduct a comprehensive inspection of all rubber seals on doors and windows, and replace aged, cracked, or shrunken rubber strips (such as EPDM strips) to ensure a tight fit after closing.
Adjust the locking points of door/window hardware, tighten loose components, and directly replace severely worn hardware to ensure the sash tightly fits the frame after locking.
Seal profile joint gaps with specialized sealing materials to reduce air infiltration channels.
IV. Daily Maintenance and Prevention Tips
Regularly inspect the appearance, seals, and drainage holes of doors and windows, with a special focus on checking the condition of exterior weather-resistant sealant before the rainy season.
Avoid using strong corrosive cleaners when cleaning doors and windows to prevent accelerating the aging of seals and sealant.
After heavy wind and rainstorms, promptly check for water stains near window edges to detect and address problems early.
Air and water leakage in doors and windows is rarely caused by a single factor; in most cases, it results from a combination of issues across sealing, hardware, installation, and drainage. Proper construction control in the early stages, combined with regular maintenance, can significantly reduce the likelihood of leakage and drafts, extending the overall service life of doors and windows.