Fill Hole In Cavity Wall.

[Brian1960]

I've just removed a very old cooker back box from a kitchen wall.
The wall is a Thermalite cavity structure, on removal of the box I'm left with a gaping hole that goes right into the cavity.
How do I make this good please?
Was thinking of patching in with Thermal Insulation Board, leaving slightly under then plaster over.
Any suggestions most welcome, thank in advance.

 

[Wayners]

Buy a thermalite block, then that will cut easy with a hand saw to fit hole. Go buy small sand and cement mix, the sort you just add water. Bung block in the hole with mortar then decorators filler over. Sand and paint

 

[^woody^]

Expanding foam is a gift from God.