Best way of fixing boxes to crumbly walls.....

[LewisM]

Hi I'm doing a rewire of an old victorian terraced house built in the 1890s the plaster and bricks are extremely fragile even with a hammer and scutch chisel the brick just crumbles away leaving no solid fixing, what is the best way of fixing boxes back square? I've thought about expanding foam but will that not expand and push the boxes back out?

It's hard to see from the picture but the brick is all jageded and in pieces.

 

[Micktw68]

A tight mix of Coving adhesive. The Knauf one seems to work best, even better if it’s gone off in the bag a bit as it sets lightning fast.

 

[davesparks]

What about surface mounting all boxes and sleeve it up the wall or across the wall using PVC conduit

That would be as ugly as hell in a house.

 

[Taylortwocities]

Spray it with water and slap some bonding in there.

If you want it to go off quick mix a bit of cement in with the bonding and it'll go off in no time.

Another vote for that solution. Bonding with a bit of cement in the mix.

Do make sure the box is set level. The mix goes off extra quick and hard, so there’s no adjustment later!

Either drill through the box and screw to fix - after the bonding has set!
Or pop out a couple of the knock outs. The bonding will come through a bit into the box and hold the box firm.

 

[Mike Johnson]

I hate it when removing a plug the back box comes with it, this resin will fix anything: Rawlplug R-KEM II Styrene-Free Polyester Resin 300ml. if you have not used it before be aware that the nozzles are one use only unless you are quick and have a few to do.

Have mixed it on a board before now when all my nozzles have gone solid, just squeezed out of the tube onto the board and mixed with a disposable stick, not your favourite screwdriver.

 

[LukeD]

Another vote for that solution. Bonding with a bit of cement in the mix.

Do make sure the box is set level. The mix goes off extra quick and hard, so there’s no adjustment later!

Either drill through the box and screw to fix - after the bonding has set!
Or pop out a couple of the knock outs. The bonding will come through a bit into the box and hold the box firm.

Bend out the nock outs this creates a much better hold . But again , bonding on a ground floor might not be a good idea . It draws in any damp

 

[PEG]

If you get 1 or 2 fixings drilled first,mix some decent quality drywall adhesive up (use puddle water or bird bath,it goes off faster) load out recess,leaving screw plugs visible,push in flush & level,fit screws loose,tighten an hour later.

I have such a property,built 1911,and this method has worked well on the other many dozen i've applied love to.

A very good pal of mine,had a similar issue....and also has a touch of Aspergers.....on giving him the same advice,he listened,and said "....but a period property like this,traditionally had only a yard at the rear...so would not have the option of an ornamental bird bath...." just can't argue with that...

 

[Rockingit]

Always used to have a bag of bonding on the van back in the domestic days