Window frame - repair wall

[cpmarvin]

Hi,

What would you recommend for filling the gaps between the brick the frame. My goal is to minimise the sound leak, second is of course heat loss.

I'm inclined to use boanding coat rather than foam. Any advice

I have no idea what to do for the top one, add another wood piece in between, foam or bonding?

 

[Wayners]

Plasterboard cut tight. Seal board edges and wall with PVA and stick in.
Plaster over

Would help if you filled that small gap with foam if you had any.