How do I fill this gap?

[redhexagonal]

i have a large beam that cuts through the corner of a room and there was some loose filler between the plasterboard and the beam which i raked out, now there a few large gaps down the side of the beam, almost 10mm wide that go up into the loft. Whats the best way to fill this gap?

 

[ktuludays]

You can buy lightweight deep crack filler that won't sag under it's weight.

 

[redhexagonal]

You can buy lightweight deep crack filler that won't sag under it's weight.

Would easifill or toupret work? Should i shove anything in the gap first?

 

[Wayners]

Use lightweight filler. Very low water content and has a bit of give vs other sorts of filler that are hard and may crack out again.

You know you found right stuff as pot feels empty. Push plenty in