Sealing around balcony sliding door frame - advice / tips?

I recently purchased an apartment on the top floor of an established complex (constructed approx 13 years ago). The apartment has two balconies which are practically identical in layout, comprising floor to ceiling glass panels and aluminium (I think) frame, with the two middle panels sliding open and the outer panels fixed in place. The first picture shows the balcony off living room for reference.

I’ve recently noticed small gaps on the internal side of both balconies where the frame adjoins the plaster wall. I’d like to fill the gaps with the obvious aim of weatherproofing, but I also want to do whatever I can to best minimise outside noise as I live in a high density area with construction work and traffic noise.

Based on my limited knowledge, I think the gaps are the result of the original sealant degrading over time (although I’m unsure what (if any) sealant may have originally been there) and / or the building simply settling over time - and that it’s nothing to be too concerned about.

I’m hoping that with the correct product, it should be a relatively easy fix for me to do myself. I’d appreciate any advice / tips / thoughts on recommended product, application techniques / things to be mindful of when applying. I’d also welcome any feedback on whether I’m being optimistic about the cause and if this is / could be a sign of a bigger issue, and whether a professional tradie would be better placed to fix it.

Thank you!
 Living room balconyLike  ⋅  Add a comment  ⋅  Pin to Ideaboard  ⋅  Share
 Gap/separation between inside of frame and plaster wallLike  ⋅  Add a comment  ⋅  Pin to Ideaboard  ⋅  Share
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 Bottom skirting/Ledge with gap Note: The tubing runs to a newly installed Aircon unit.Like  ⋅  Add a comment  ⋅  Pin to Ideaboard  ⋅  Share
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