Symptom: water easily leaks through the gap between the aluminium frame and wall and at the lower track, especially in storms, flowing indoors along the frame. Solutions: form a drip groove and drip line on the lintel, and make the sill slope outward with a gradient of at least 10%; pack the frame-wall gap tightly with mineral-wool felt and seal the outside with quality sealing material; and seal the tenon joints, rivets and stays with waterproof silicone.