Filler for awkward gap

[harryagain]

You need scrim.

[RJH]

I need to fill the space between a newly plastered ceiling and a purlin:

It all seems quite airtight, but I want to finish it off for neatness, avoiding draughts, and stopping any much coming down from the loft.

I'd guess something that stays quite flexible, can be squirted into that gap in a thick bead, and is easy to finish off smoothly. Any suggestions please?

[Dave Plowman (News)]

I've personally not found anything better than a decent decorator's caulk. Snag is they all shrink so need several applications. But do dry quickly. So IMHO worth the effort.

I have an old house which moves around a bit, and modern plaster/plasterboard always seemed to show cracks somewhere. Taking time to fill smooth with DC seems to work better than anything else I've tried.

[Cursitor Doom]

+1 on the caulking. I've not experienced any shrinkage to the extent that several applications are required, though!

[tabbypurr]

The only flexible sealants are bath sealants, ie silicone, acrylic and what's it called, ms polymer? Acrylic is paintable, silicone isn't. The few attempts to use these type of sealants I've seen have all looked bad.

Ordinary filler works - it has no flexibility so will need patching now & then. Decorators' caulk has so little flexibility that to all intents & purposes its not flexible & lasts no better IME.

NT

[F Murtz]

We have stuff called "No more gaps" that is used for that sort of thing, It may be the same as you call decorators caulk. You could google "no more gaps" and see if it is the same.

[Dave Plowman (News)]

There is scrim between boards - you can see it when raking out the joints. Didn't stop the skim cracking.

[Dave Plowman (News)]

Have you filled cracks in a smooth surface, though?

[The Natural Philosopher]

yes