light switch, lath & plaster walls help please

[happyhero]

Hi my father is decorating and has the light switch adrift from the wall. I have looked at it and it is a lath and plaster wall with no back box and about a 6" cavity behind. The screws just turn and do nothing and there does not seem a way to catch the laths to fix to.

Do light switches have to have back boxes in the first place (just thinking of the options) as many of his other switches seem to have wooden pieces in the back forming a box?

Does anyone have any clever way to fix this light switch so it could come off again if necessary ie I do not think silicon fixing would be a good idea?

I have racked my brains with different ideas like using a plasterboard back box or putting wood in the wall and fixing a metal clad back box but none seem that they will work very well. With a plasterboard box it would not work very well as first I would have to get a very accurate cut which this type of wall does not seem to allow very easily and then it has all different thickness's to deal with.

There must be a way as electricians must hit this problem all the time. Any help would really be appreciated.

 

[Ghughes]

forgive my ignorance, whats lath?

How about a surface mounted box?

http://www.screwfix.com/prods/62410...ed/Marbo-Range/Marbo-1G-47mm-Surface-Pattress

 

[Chri5]

If you can cut the square cleanly then a extra deep dry lining box will do the job.

The deep ones have much better jaw gap which will overcome the issue of depth for plaster and lath.

 

[EdwardCurrent]

Hello HH.

I would get 3 X @175mm bits of batten, fix the two side battens top and bottom, then hold the third across the centre horizontally and fix. Then you can screw your 'knockout' box to this. There sounds like making good will be required anyway, so a few screwheads wont be too much hassle .

I hope that this is of some help.
Cheers.
Ed.