An inspection found that I need to close an uneven gap at the head of my fire door.During the cutting the head level, and then rebuilding, to fill the gap, I need to plough a groove in the new section to fit an intumescent strip.
I located these at Screwfix:
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Reading the included info, I see:"As a guide, only use 15mm seals on new door application and 10mm seals for replacement / retrofitting."
As the existing strips around the rest of the door are 15mm, is there a subtle reason, that I'm missing, which would make it necessary for me to use the 10mm strip, rather than continuing with the existing
15mm stuff?
I know this seems like a trivial question, but my old creaking joints cause me to be increasingly careful not to make mistakes.