Wall Insulation varies in many homes. Above is leakage in a standard mid 60s to early 90s home.
Easily remove horizontal siding including wood siding, steel siding, aluminum siding, vinyl siding.
Air leakage into exterior walls shown with hot attic heat as orange and studding as vertical dark spots.
Brick Walls may be insulated by drilling through every other mortar joint surrounding bricks.
Walls with No insulation seen on cold day.