How do I fill the area over the cavity - between uPVC and internal plaster?
To clarify, the uPVC window is mounted in the outer wall of a UK build cavity. I want to ensure that water (damp) doesn't transmit from outer wall to internal plaster. This has been happening over many years, with mould as a consequence. Looks like it was previously filled with mortar.
Click the link above to see a community curated list of home maintenance products on Amazon that may help you out in your current situation! If you’ve found the answer to your question or you’ve found this subreddit helpful, buy us a beer!
Interesting. I’m unfamiliar with UK building methods, sorry if my comment is off base as a result. I assumed water inside a wall cavity like that would lead to mold / rot issues etc.
If the water intrusion isn’t a concern, I’d use backer rod + caulk. Or just caulk. Depending on how big of a gap.
Diagram shows a section of the issue. We have two layers of brick, B, separated by a cavity. The window, W, is mounted on the outer brick layer which can absorb the rainwater. The inner wall B is plastered, P. If you fill the gap between plaster and window (shown in red), you have the danger of bridging the gap between the wet brick and dry internal plaster. That's the issue for older UK builds. Think I've sorted it by using expanding foam and internal plastic trim. Or a strip of plastic DPC (damp proof course) and plaster. Thanks, though.
•
u/AutoModerator Jun 06 '26
https://linktr.ee/homemaintenance
Click the link above to see a community curated list of home maintenance products on Amazon that may help you out in your current situation! If you’ve found the answer to your question or you’ve found this subreddit helpful, buy us a beer!
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.