Non-sealer window renovation
method to ensure airtightness and watertightness

The frame-cover installation method for single-family homes has allowed new window frames to be installed over existing frame openings. Although this method is much simpler than chipping the exterior wall, the frame-cover method requires sealing the space between the old and new window frames and thus requires technical skill.
To ensure a high level of airtight performance and watertight performance without relying on the skills of installation technicians, YKK AP developed the Non-Sealer Cover Method. This method, the industry’s first for windows in single-family homes, does not necessitate sealing and has been employed since 2016. It addresses the chronic shortage of installation contractors and the decline in the number of skilled workers in the construction industry.

The Non-Sealer Cover Method uses an airtight sheet that is applied instead of a sealant. The purpose of conventional sealant has been to fill the gap between the old and new window frame openings in order to prevent rainwater and outside air from entering.

Water and air move between the inside and outside of a building due to differences in air pressure. If the outside pressure is high and the room’s pressure is low, rainwater will seep through any gaps. YKK AP’s Non-Sealer Cover Method encloses the gap between the former and new window frames with a single airtight sheet, creating a pressure-equalized structure with no difference in air pressure between the inside and outside of the building. This prevents rainwater infiltration and ensures that even during a typhoon (hurricane), rain doesn’t seep into the window frame. Additionally, using the airtight sheet helps block cold air from outside and water vapor from inside, preventing condensation. While window frame specifications for single-family homes vary widely, the sheet can easily wrap around various shapes, ensuring airtightness.
Furthermore, the airtight sheet can be installed from inside the room, eliminating the need to set up scaffolding outside even for second-floor window renovations. This allows for construction in challenging conditions like tight spaces. Compared to conventional methods that require sealing, this method can reduce construction time by at least 20 minutes (* based on YKK AP testing).
In window renovation, the Non-Sealer Cover Method has achieved groundbreaking simplified installation, allowing for high quality results without the need for an installer with special expertise. It offers customers significant waterproofing and improved thermal insulation, in addition to preventing condensation inside window frames.