Hi everyone. I have recently moved into a new (to me) house. I was replacing a damaged socket front and noticed the backbox was loose. It was nailed in place and not really soundly fixed as there was a large void( 1 inch or so) deep. So although my query isnt strictly electrical, i thought it may a be a good palce to get an answer to my question " What should i fill the void with to enable me to fix it securely?". I was thinking polyfiller, but i also have some plaster and cement knocking around. Is expanding foam suitable? Any advice would be gratefully received.