The plum rain season is here—are you experiencing leaks on your windowsill? We’ve got all the solutions covered!
Release date:
2025-09-01
Spring has arrived—grass is green, flowers are red, and another vibrant season is upon us. Yet, with increased rainfall comes the pesky Meiyu season. For older homes, leaking window sills have long been a common issue. Is your window sill leaking? Drawing from our past construction experience, we’ve compiled seven typical scenarios where leaks might occur. Take a look and see if any apply to your situation!
1. During the installation of aluminum alloy window frames, the gaps between the frame and the wall were not filled with flexible materials but instead directly sealed with ordinary cement mortar. As a result, when the window is subjected to excessive wind loads, the frame is prone to deformation, creating cracks between the frame and the mortar—allowing rainwater to seep into the interior.
Treatment method: If the water seepage isn’t severe, you can reseal it with weather-resistant sealant. However, if the issue is serious, you’ll need to chip away around the window frame and apply a three-coat, two-layer waterproofing system. Once fully dry, proceed with painting and applying sealant.
2. During the assembly of the aluminum alloy window frames, waterproof sealing gaskets were not installed, allowing rainwater to seep in through the gaps between the aluminum alloy sections.
Treatment method: Locate the leak, and seal the source of the water intrusion with waterproof sealant.
3. Before applying the sealant around the window frame, dust and debris remaining in the joints between the wall and the window frame were not thoroughly removed, leading to poor adhesion of the silicone—potentially causing it to peel off entirely—and ultimately rendering the sealant ineffective.
Method: Clean off the old adhesive and dust thoroughly, then reapply the sealant.
4. The window sills lack drip edges, and in some cases, water even flows backward, causing rainwater to run down the sills, seep into the gaps around the window frames, and eventually penetrate indoors.
Treatment method: Reinstall a drip course using thicker tiles, cut into 2–3 cm strips and adhered with weather-resistant adhesive to create the drip-line shape.
5. The outer edge of the windowsill lacks a drainage slope or has an insufficient slope, leading to poor water flow. In prolonged rainy weather, rainwater can easily seep through the plaster layer beneath the window frame, resulting in water leakage.
Treatment method: Directly chisel out the water slope, finish it with tiles, and seal the junction between the tiles and the window frame using weather-resistant adhesive.
6. Cracks have appeared in the wall beneath the window frame, allowing rainwater to seep into the room through these cracks.
Treatment method: Chisel open the plaster layer at the crack, inject and seal it thoroughly with LB-7 chloroprene latex polymer cement slurry, then apply localized waterproofing treatment using LB-23 high-performance, crack-resistant waterproof cement mortar.
7. The absence of drainage holes on the windows, or blocked drainage holes causing poor water flow, has resulted in rainwater leaking into the interior.
Treatment method: Add additional drainage holes and clear existing ones.
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Address: Area A, Datang Park, Sanshui Industrial Park, Sanshui District, Foshan City, Guangdong Province
Warren Doors & Windows, South of Fangshan Road and West of Dongtai Road, Dongcheng Subdistrict, Linqu County, Weifang City, Shandong Province
Business Inquiries: BD@warren.net.cn
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