Why are we still discussing the "three staple items" today, given that we are selling doors and windows?

Preface: Three Major Exams through a Window

If doors and windows are compared to the "five senses" of a building, then air tightness, water tightness, and wind pressure resistance are the three core physical examination indicators that determine whether these senses are "healthy".

Air tightness - whether there is air leakage during "breathing"

Watertight - whether the "skin" is permeable to water

Wind resistance - can the "skeleton" withstand strong winds

These three properties not only affect the comfort of living, but also directly determine energy consumption, safety, durability, and future maintenance costs.

Air tightness: an invisible "financial leakage" black hole 1. Definition and classification

Air tightness refers to the ability of doors and windows to prevent air infiltration when they are closed, with the unit being m³/(m·h·Paⁿ).
GB/T 31433-2015 divides the air tightness of external doors and windows into 8 levels (level 1 being the worst and level 8 being the best), with the commonly used indicator being the air leakage per unit length of seam under a pressure difference of 10 Pa.

For example, passive houses and ultra-low energy consumption buildings should meet an air tightness level of 8 or above. Residential buildings with central heating in the north should preferably meet a level of 6 or above. Other ordinary residential buildings without special requirements should preferably meet a level of 4 or above.

2. Performance logic

As we all know, once thE Windows leak air, the room will naturally become hotter in summer and colder in winter, especially when air conditioning or heating is turned on. This effect is particularly significant.

On the other hand, for every 1 m³/(m·h) decrease in air leakage through windows, the resulting heat loss will increase. When the sealing level of All Doors and windows in the house is improved, under the same conditions, it is not a problem to increase the indoor temperature by 3 or 5 degrees in winter. A house with higher comfort created in this way will naturally make people feel more rested.

From a personal perspective, if the air tightness of the windows is not up to standard or even quite poor, the cold wind outside can make one feel extremely uncomfortable when standing in front of the window. In other words, the area around the window becomes completely off-limits, "wasting" a significant portion of the inDoor Space and affecting comfort.

3. Improve skills

Profile: Improve the integrity of the profile, such as applying seamless welding technology to the outer aluminum

Rubber strip: The rubber strip should appear as a single, unbroken piece to the naked eye

Process: Refine equipment and technical errors, raise standards, and ensure tight and sealed joints

Hardware: Multi-point locking system ensures uniform circumferential pressure, making it sturdy and reliable

Water tightness: The first line of defense during typhoons 1. Definition and classification

Water tightness refers to the ability of doors and windows to prevent rainwater infiltration under the simultaneous action of wind and rain, with the maximum non-leakage pressure expressed in Pa.
GB/T 31433, Grade 6 (Grade 1: 100 Pa, Grade 6: ≥ 700 Pa).
Projects in coastal typhoon areas often require a pressure rating of ≥ 5 (500 Pa) to prevent water infiltration.

2. Leakage mechanism

Wind and rain coupling → water accumulation in cavity → poor drainage → pressure difference between inside and outside → rainwater inflow.
The experiment showed that 90% of the leakage occurred in ① the contraction of the corner rubber strip, ② the splicing seam of the middle support, and ③ the lower sliding drainage groove being blocked by cement mortar.

3. Improved design of the pressure chamber: The external chamber maintains pressure balance with the outside, eliminating the "siphon" effect. Hidden drainage: The drainage hole is located on the inner side, which not only prevents blockage but also allows for vertical drainage by gravity, ensuring faster drainage. Vulcanization of the rubber strip corners: The rubber strip appears as a single piece to the naked eye, without any breaks

Wind load resistance: a critical threshold for high-rise buildings and coastal areas 1. Definition and classification

Wind pressure resistance refers to the ability of doors and windows to maintain structural integrity and normal function under the action of wind load, measured in kPa.
GB/T 31433 is divided into 9 levels (Level 1 ≥ 1.0 kPa, Level 9 ≥ 5.0 kPa).
Taking a 200-meter super high-rise building as an example, according to GB 50009-2012, with a basic wind pressure of 0.75 kPa and a gust factor of 1.8, it requires a wind level of ≥ 8 (3.5 kPa).

2. Destructive mode: Glass breakage: Deflection at the center under positive wind pressure exceeds the limit, and stress concentration at the edge under negative pressure leads to plastic deformation of the profile: The central support deflects with irreversible rebound. Hardware failure: Lock points break, sliding supports fall off, and the entire window is lifted off.

3. Improvement techniques: Profile wall thickness: The wall thickness of the main load-bearing aluminum material is ≥1.8 mm, and for super high-rise buildings, configuration should be strengthened according to actual conditions. Strengthening the central support: After calculation by the research and development designer, it is necessary to add a strengthened central support to increase support force. Glass configuration: Generally, for buildings with ultra-high wind pressure resistance requirements, adding laminated glass is a safer choice, but it is important to note that not all tempered glass is necessarily good. Lock point arrangement: Lock points should be arranged around the window frame to prevent corner lifting due to negative pressure

Three-dimensional linkage: 1+1+1>3

Air tightness, water tightness, and wind pressure resistance are not isolated but interrelated:

Wind pressure resistance is the "skeleton". If the skeleton is unstable, the sealing of the rubber strip will fail, leading to a collapse of both air tightness and water tightness
Watertightness is akin to a "skin". Once water seeps in, the frame material ages, leading to a vicious cycle
Air tightness is akin to "immunity". Leakage can lead to heat loss, condensation and corrosion of metal hardware, ultimately reducing the wind pressure resistance and lifespan

Air tightness, water tightness, and wind pressure resistance are like the "three health check indicators" for doors and windows. Any shortcoming in any of these aspects can instantly undermine the high-end configuration. In 2025, with upgraded national standards, material iterations, and transparent testing, consumers can rely solely on data to ensure that every penny is spent on genuine performance.

Next time you enter an exhibition hall, don't let the hype of "aviation-grade" or "superior sound insulation" sway you. First, ask:

"Please take out the three-property testing report."

—— This is the best opening remark.