Do you know how important the water tightness of doors and windows is?
Release date:
2025-09-01
The water-tightness performance of exterior windows is one of the three key performance characteristics of doors and windows—and it’s the most critical among them. Water-tightness refers to a closed door or window’s ability to prevent rainwater from leaking in, even when exposed simultaneously to wind and rain.
If the water-tightness performance of exterior windows is poor, rainwater can easily seep into the room during windy or rainy weather, carried by the force of the wind. Casement windows, equipped with high-quality components and a unique design, deliver exceptional water resistance. Below, we’ll reveal the science behind their outstanding water-tightness capabilities.
If the water-tightness performance of exterior windows is poor, rainwater can easily seep into the room during windy or rainy weather, carried by the force of the wind. Casement windows, equipped with high-quality components and a unique design, deliver exceptional water resistance. Below, we’ll reveal the science behind their outstanding water-tightness capabilities.
One: Uses high-quality sealant
Between the window sash and the window frame, as well as between the glass and the sash, an anti-aging, highly elastic sealant is used—its material meeting the physical performance standards outlined in the national standard GB1200289 ("Sealing Strips for Plastic Doors and Windows"). When the window sash is closed, the sealant effectively presses against the window frame, significantly reducing the risk of rainwater infiltration.
2: Multi-stage Sealing
On the outer, central, and inner sides of the window sash—each in contact with the window frame—sealing strips are installed on the inner side of the sash, creating a triple-seal system. The outer seal effectively blocks rainwater, while the inner seal prevents outdoor air from entering. Meanwhile, the central seal forms an air cavity that efficiently prevents rainwater from seeping indoors, even under the pressure of external winds. Additionally, the inner wall of the window frame has been designed with an elevated edge to further shield against rainwater intrusion.
Third: High machining precision results in extremely small gaps at corners and in the mullion connections.
The four corners where the window sash meets the frame—and specifically the connection between the mullion and the window frame—are prone to developing gaps. If the manufacturing precision is poor or there are significant angle errors, these gaps can become larger, making it easier for water to seep in. By using German-imported processing equipment with high precision, we ensure that all joints fit tightly together, minimizing even the smallest gaps and effectively preventing rainwater from penetrating through them.
Meanwhile, thanks to their high precision, the profiles fit seamlessly with accessories such as glazing bars, corner connectors, and hinges, creating a tight assembly that minimizes pathways for rainwater infiltration—from the exterior all the way to the interior.
Four: A Unique Isothermal Chamber Design
Outdoor wind often creates pressure on the interior, causing rainwater to seep inward along this pressure gradient. However, in casement windows equipped with an additional central sealing strip between the sash and frame, the cavity between the frame and sash is effectively divided into two distinct chambers: an outer water-tight chamber and an inner air-tight chamber. The outer chamber acts as an equal-pressure zone, ensuring that the pressure inside remains balanced with the outdoor environment—thus preventing rainwater from entering the room. Meanwhile, thanks to the principle of siphoning, the accumulated rainwater naturally flows outward under gravity.
2: Multi-stage Sealing
On the outer, central, and inner sides of the window sash—each in contact with the window frame—sealing strips are installed on the inner side of the sash, creating a triple-seal system. The outer seal effectively blocks rainwater, while the inner seal prevents outdoor air from entering. Meanwhile, the central seal forms an air cavity that efficiently prevents rainwater from seeping indoors, even under the pressure of external winds. Additionally, the inner wall of the window frame has been designed with an elevated edge to further shield against rainwater intrusion.
Third: High machining precision results in extremely small gaps at corners and in the mullion connections.
The four corners where the window sash meets the frame—and specifically the connection between the mullion and the window frame—are prone to developing gaps. If the manufacturing precision is poor or there are significant angle errors, these gaps can become larger, making it easier for water to seep in. By using German-imported processing equipment with high precision, we ensure that all joints fit tightly together, minimizing even the smallest gaps and effectively preventing rainwater from penetrating through them.
Meanwhile, thanks to their high precision, the profiles fit seamlessly with accessories such as glazing bars, corner connectors, and hinges, creating a tight assembly that minimizes pathways for rainwater infiltration—from the exterior all the way to the interior.
Four: A Unique Isothermal Chamber Design
Outdoor wind often creates pressure on the interior, causing rainwater to seep inward along this pressure gradient. However, in casement windows equipped with an additional central sealing strip between the sash and frame, the cavity between the frame and sash is effectively divided into two distinct chambers: an outer water-tight chamber and an inner air-tight chamber. The outer chamber acts as an equal-pressure zone, ensuring that the pressure inside remains balanced with the outdoor environment—thus preventing rainwater from entering the room. Meanwhile, thanks to the principle of siphoning, the accumulated rainwater naturally flows outward under gravity.
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Contact Information
Contact Address: No. 7, Industrial Avenue East, Songxia Industrial Park, Shishan Town, Nanhai District, Foshan City
Warren Doors and Windows, south of Fangshan Road and west of Dongtai Road, Dongcheng Subdistrict, Linqu County, Weifang City, Shandong Province
Become A Deaters :Info@wolunmc.com
National customer service hotline:+86 400-676-9888
WhatsApp:+86-18866798677
Beijing customer service phone number:+86 010-68319888
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