ᐅ Retrofitting Seal Between Aluminum Window Sill and Window Frame from the Outside

Created on: 19 Aug 2025 15:46
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Bauherr am L
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Bauherr am L
19 Aug 2025 15:46
Hello,

unfortunately, we are missing the so-called screw flange gasket between the window sill screw flange and the window frame profile to ensure a rain-tight installation of the window sill. This is how the edge looks in our case (without gasket and without compressible sealing tape behind it):


Close-up of a metal cladding in the window area with seam and small black covering


Now, I have noticed on a building (around 5 years old) something on the windows that appears to be a retrofitted or externally applied seal at the window sill screw flange to the window frame profile:


Close-up of window frame at the base area with pink arrows pointing to the gap


This could be a solution to our problem. However, I have not been able to find anything suitable through online searching.

Can you help me? Thank you!
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nordanney
19 Aug 2025 16:10
Anything added afterward, which cannot seal as effectively as the original sealant, also won’t really help in your case, based on your picture. For example, I would use Ottoseal M360.
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Bauherr am L
19 Aug 2025 19:06
The part I photographed looks more stable than a sprayable joint. I would really like to know how this part is called or how to find it.
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nordanney
19 Aug 2025 19:35
Bauherr am L schrieb:

The part I photographed looks more solid than a sprayable joint. I would really like to know what this part is called or how to find it.
Maybe @11ant, as an experienced window specialist, can help. I would have more confidence in Ottoseal.