How to fill holes in old plaster rendered brick walls?

Burnside7

I have a very loose light switch on an internal wall. It sits about 2.5cm out from the wall.

The internal wall is old style plaster (fairly sandy) over brick. The screws and plugs have come away and I have been trying to get rid of all loose material so I can fill the holes left and then re-screw.  But the plaster just keeps on giving away and the holes get bigger.

Any ideas on how to stop the plaster continuing to give/erode and/or how to fill to enable re-screwing?  (Please note that because it is a light switch, I don't have many options in terms of putting the screw holes elsewhere.)

JacobZ

Hi @Burnside7,

Thank you for your question.

I'll start by saying that you should make sure the power is off when you are working around exposed wiring and get an electrician in to do any fit-off work.

Once the power is off and safe to work around, I would suggest you give the area an initial sand with an 80 Grit Sanding Sponge to remove the undulating surface. It's not 100% necessary, but you will get a nicer finish around the light switch in the end.

I would then fill the holes with Builder's Bog, wait for it to dry, then predrill a hole and insert a Green Wall Plug. You can then have an electrician fit off the light switch and screw it in place.

You can then tidy up the flaked off plaster with Less Mess Topping Compound, give it a sand, then prime and paint.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob