Cavity Walls

[Nottm_George]

My son is blocking his garage door off and wants to know the best type of cavity wall to use.

[frugalfred]

Is this the door where vehicles enter or the door into the house, perhaps?

[Old_Geezer]

Shows how naive I am. I've only ever come across the type with a gap between the two walls.

[Nottm_George]

Sorry I didn't explain in properly, he is blocking the garage door off and wants to use some insulation in the cavity he is also putting a ordinary door in and a window.

[Buenchico]

This might help:
https://www.homebuilding.co.uk/how-to-insulate-a-wall/