Cementing in metal backboxes.

Hia all hope I am not making a prat of meself by asking this question. But first the dilemma.

I have tried to chisel out a single and double box next to eachother (25mm back boxes)

In doing this I have shattered about a brick and a half out of the internal wall of the cavity. I have had limited success in bonding the boxes back into the wall but they are very deeply laid in and the allignmentment is sadly all over the place. I have also plugged and screwed both boxes.

Now to the question...

Would you ladies/gents leave the back boxes as they are, or wait for the sand/cement mix to fully harden, lever out the back boxes and carefully rechase the boxes in?

Many thanks

AndyGuinness

Cant beat a nice tight bit of wood whacked into place

Well ya prob can, but i use wood, and sometimes the old expanding foam

Not a bad idea Dane, thanks, builders merchants 5 minutes walk from Me so will see what they can try and sell Me.

AndyGuinness

i love bonding in back boxes, usually fill up the chases aswell while im there. knock it up stiff and push the box in wedges be useful when leveliing.

o i use hardwall not bonding

if you've got somewhere to fix to then cut a peice of ply to mount your two boxes on, double up if you need to bring them forward more.

Had the same thing a while back chopping out for a 47mm box the whole brick went, the builder had a batch of board adhesive on the go and offered to bond it in for me, came in next morning lovely and solid. I shall defo use that little trick again.

Generally use bonding on cavity walls if its getting a bit old can go off quite quick. Working with a chap to day he had some real old stuff was perfect for fixing boxes in. If its solid walls that are damp you must use sand and strong cement as bonding will not go off. You could fill hole with plasterboard and then fix box in with a bit of bonding.

Batty

hi

i use finish plaster for accidents.......

nice and thick and push it in till it oozes out of all the holes, smashing

a bit cement mixed into plaster makes it set quicker

I have used bonding to hold back boxes securely in chased out brickwork . mix up fairly stiff ,set the backbox level and it is dry in a couple of hours so you can complete first fixing . I have never had a problem doing this and was taught it by a sparks of 40 yrs . Recently I was helping out a mate rewiring an old property with similar problems . Showed him the bonding trick and that saved a lot of time in the long run all the back boxes were level making the 2nd fix a breeze .

silicone works wonders

I have used bonding to hold back boxes securely in chased out brickwork . mix up fairly stiff ,set the backbox level and it is dry in a couple of hours so you can complete first fixing . I have never had a problem doing this and was taught it by a sparks of 40 yrs . Recently I was helping out a mate rewiring an old property with similar problems . Showed him the bonding trick and that saved a lot of time in the long run all the back boxes were level making the 2nd fix a breeze .

Click to expand...

Don't use it on damp walls it will never dry though.

[quote name='Andy

Also using dirty water will make it go off faster.

Don't use British Gypsum board adhesive it takes ages to go off, use Knauf board adhesive.