In intensified rainfall or continuous rainy days, home doors and windows often face the test of sealing and waterproofing. In addition to the well-known sealing performance, the anti-seepage and leakage prevention of doors and windows are also closely related to these.

The so-called water tightness performance (especially for casement windows) refers to the ability of closed doors and windows to prevent rainwater leakage under the simultaneous action of wind and rain (if the water tightness performance of the outer window is poor, rainwater will use the wind to leak through the window to the interior in windy and rainy weather). Generally speaking, water tightness is related to the structural design of the window, the cross-section and material of the adhesive strip, and the drainage system.

1. Drainage holes: If the drainage holes of doors and windows are blocked or drilled too high, it is possible that rainwater flowing into the gaps of doors and windows cannot be discharged properly. In the drainage design of casement windows, the profile is inclined downwards from the inside to the drainage outlet; Under the effect of “water flowing downwards”, the drainage effect of doors and windows will be more efficient, and it is not easy to accumulate water or seep.

In the drainage design of sliding windows, high and low rails are more conducive to guiding the rainwater to the outside, preventing rainwater from silting up in the rails and causing internal irrigation or (wall) seepage.

2. Sealant strip: When it comes to the water-tightness performance of doors and windows, many people first think of sealant strips. Sealant strips play a crucial role in the sealing of doors and windows. If the quality of the sealant strips is poor or they age and crack, water leakage will often occur in doors and windows.

It is worth mentioning that multiple sealing strips (with sealing strips installed on the outer, central, and inner sides of the window sash, forming three seals) – the outer seal blocks rainwater, the inner seal blocks heat conduction, and the central seal forms a cavity, which is an essential basis for effectively blocking rainwater and insulation.

3. Window corner and end face adhesive: If the frame, fan group corner, and center stem of the door and window are not coated with end face adhesive for waterproofing when splicing with the frame, water leakage, and seepage will also occur frequently. The joints between the four corners of the window sash, the middle stiles, and the window frame are usually “convenient doors” for rainwater to enter the room. If the machining accuracy is poor (with a large angle error), the gap will be enlarged; If we don’t apply end-face adhesive to seal the gaps, rainwater will flow freely.

We have found the cause of water leakage in doors and windows, how should we solve it? Here, based on the actual situation, we have prepared several solutions for everyone’s reference:

1. Unreasonable design of doors and windows leading to water leakage

◆Blockage of drainage holes in flush/sliding windows is a common cause of water leakage and seepage in doors and windows.

Solution: Rework the drainage channel. To address the problem of water leakage caused by clogged window frame drainage channels, as long as the drainage channels are kept unobstructed; If there is a problem with the location or design of the drainage hole, it is necessary to close the original opening and reopen it.

Reminder: When purchasing windows, ask the merchant about the drainage system and its effectiveness.

◆ Aging, cracking, or detachment of door and window sealing materials (such as adhesive strips)

Solution: Apply new adhesive or replace with a better quality EPDM sealant strip。

Loose and deformed doors and windows leading to water leakage

Loose gaps between windows and frames are one of the common causes of rainwater leakage. Among them, poor quality of windows or insufficient strength of the window itself can easily cause deformation, leading to cracking and detachment of the mortar layer at the edge of the window frame. In addition, the long service life of the window causes gaps between the window frame and the wall, which in turn leads to water seepage and leakage.

Solution: Check the joint between the window and the wall, remove any old or damaged sealing materials (such as cracked and detached mortar layers), and re-fill the seal between the door and window and the wall. Sealing and filling can be done with both foam adhesive and cement: when the gap is less than 5 centimeters, foam adhesive can be used to fill it (it is recommended to waterproof the outermost layer of outdoor windows to prevent soaking the foam adhesive in rainy days); When the gap is greater than 5 centimeters, a portion can be filled with bricks or cement first, and then reinforced and sealed with sealant.

3. The installation process of doors and windows is not rigorous, resulting in water leakage

The filling materials between the aluminum alloy frame and the opening are mainly waterproof mortar and polyurethane foaming agents. The unreasonable selection of waterproof mortar can also greatly reduce the waterproof effect of doors, windows, and walls.

Solution: Replace the waterproof mortar and foaming agent required by the specifications.

◆ The outer balcony is not well prepared along the water slope

Solution: Proper drainage is essential for proper waterproofing! The outer balcony needs to be matched with a certain slope (around 10 °) to better exert its waterproof effect. If the external balcony on the building only presents a flat state, then rainwater and accumulated water can easily flow back into the window. If the owner has not made a waterproof slope, it is recommended to choose the appropriate time to remake the slope with waterproof mortar.

The sealing treatment at the joint between the outdoor aluminum alloy frame and the wall is not rigorous. The sealing material for the outdoor side is generally silicone sealant (the selection of sealant and the thickness of the gel will directly affect the water tightness of doors and windows. Sealants with lower quality have poor compatibility and adhesion, and are prone to cracking after the gel dries).

Solution: Select a suitable sealant again, and ensure that the middle thickness of the adhesive is not less than 6mm during gluing.