Determine if wall has cavity

[omph]

Are there any devices that allow you to see through a wall to established whether it has a cavity or not ? and whether it is filled or not ?
I am trying to established the best way to establish a cavity being present without having to drill.

 

[Deleted member 281264]

Window board/revel thickness is usually a good indicator. Camera and drill needed to see inside cavity

 

[John D v2.0]

As above and if it's not rendered look and see the bond, if you can see the ends of some of the bricks, it's probably solid.
Air bricks can be a good way to look inside without drilling.
Age of house can help, 30s on was usually cavity

 

[freddiemercurystwin]

Have a look at the top of the wall in the loft.

 

[big-all]

1907 house here unusual has a cavity as said thickness and bonding gives clues
my house mid terrace between houses 2 bricks no cavity but visual by between house detail so the clues are there basically measure surface to surface then deduct plaster and render and 2 layers off brick and the rest is cavity

 

[jeds]

Age, type, materials, thickness of the walls plus a photo might help to say whether it has or might have a cavity, or whether it might possibly be insulated?