Installing flush light switch in lath & plaster wall

[ilikewatchingtv]

Hi, and thanks in advance for any help!
I'm currently attempting to rewire the lighting circuit on the first floor of my house, and want to replace most of the current ceiling pull switches with flush mounted wall switches. However, one of the walls where I wish to mount a switch is a plaster and lath partition, and I have no idea if you can buy back boxes which will mount in this type of wall, - I've tried a plasterboard back box, but the securing lugs aren't deep enough to be used in my wall - does anyone have any helpfull suggestions?

 

[DIYANIMAL]

carefully is the answer.

Cut out the box size in the laths with a plasterboard saw. use a 16mm steel box.

You'll probably need a good bit of bonding coat to stick the box in situ, or gripfill or similar.