How do I fill this?

[H F]

In our hallway, there is annoying gap between the last beam and the poorly fitted plasterboard. It’s unsightly, and it also allows for drafts.

 

Space is limited. I thought of polyfilla first, but it’s difficult to get in, and sanding it later will be a problem too. The gaps are quite wide to caulk. 
 

Suggestions welcome.

[Bitpipe]

I suggest you chew toilet roll (admittedly can be hard to find these days but worth a look) and insert it in the gaps.

 

The saliva acts as a harding agent but retains flexibility.

 

 

[MikeGrahamT21]

You've got/had woodworm! Suggest you get that checked out asap!

[Gone West]

This is good for small areas.

 

https://www.wilko.com/en-uk/unibond-whiteteq-expanding-foam-500ml/p/0457575

 

 

[scottishjohn]

pull out strip of PB fill behind with foam or what ever --refit PB when it still sof-pb should stick to it  -trim off foam as required ?

Edited March 9, 2020 by scottishjohn

[H F]

20 minutes ago, MikeGrahamT21 said:

You've got/had woodworm! Suggest you get that checked out asap!

Had woodworm. I’ve treated all the beams. Should all be gone now. Fingers crossed.

[H F]

I had thought of expanding foam. Removing the PB and then putting it back in after the expanding foam has been introduced is a good idea.