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I had one of those horrible walls the other day... just a couple of back boxes to sink in but behind the plaster was like a nasty course textured block that just fell apart. No fixings were possible... even knocking a little wooden wedge in behind to give something to screw to didn't work.

Just wondering what everyone uses in this situation... I always keep a bag of rapid set sand/cement with me, but wondering if I'm missing a trick with something more modern, simpler and less messy.
 
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Megawatt

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I had one of those horrible walls the other day... just a couple of back boxes to sink in but behind the plaster was like a nasty course textured block that just fell apart. No fixings were possible... even knocking a little wooden wedge in behind to give something to screw to didn't work.

Just wondering what everyone uses in this situation... I always keep a bag of rapid set sand/cement with me, but wondering if I'm missing a trick with something more modern, simpler and less messy.
@Zerax grab a chisel or screw driver and knock the crap out of it especially if it’s already crumbling
 

happyhippydad

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I had one of those horrible walls the other day... just a couple of back boxes to sink in but behind the plaster was like a nasty course textured block that just fell apart. No fixings were possible... even knocking a little wooden wedge in behind to give something to screw to didn't work.

Just wondering what everyone uses in this situation... I always keep a bag of rapid set sand/cement with me, but wondering if I'm missing a trick with something more modern, simpler and less messy.
My heart always drops a little when you feel the wall crumbling. You've almost drilled your rawlplug hole and then... it cracks open. You try another place and it all just crumbles!
I do find that with a bit of patience (Non hammer on sds, or just a little hammer if absolutely needed) you can usually drill a hole as long as you don't try and rush it. I like the LAP back boxes as they have extra securing holes in them so you have more choice with regards drilling position. There is always a piece of hard stone among the crumbly bits.
A small amount of times the above has failed and I have just used grab adhesive which has given a very firm hold (I Hoover out the hole first).
Is be interested if Andy or Tel could say why drywall adhesive is better?
 

Andy78

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A small amount of times the above has failed and I have just used grab adhesive which has given a very firm hold (I Hoover out the hole first).
Is be interested if Andy or Tel could say why drywall adhesive is better?
Lots cheaper, is made to fill and dry to a greater depth, can be drilled when dry unlike grab adhesive which tends to crack.

I can see how grab adhesive could be useful for convenience though.
 

telectrix

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Is be interested if Andy or Tel could say why drywall adhesive is better?

quick set. cheap as you can usually scrounge some from the dot and dab donkeys.
 
I find the hammer action on all sds drills to be very aggressive and only suitable to new/solid brick and blockwork . If you have to drill into old material that has a tendency to fall apart use your combi drill on hammer action .
 

Andy78

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I find the hammer action on all sds drills to be very aggressive and only suitable to new/solid brick and blockwork . If you have to drill into old material that has a tendency to fall apart use your combi drill on hammer action .
I have a small Milwaukee 12V one for nice gentle work. Managed to drill a 5.5mm hole 6mm away from an external brick corner today without any shattering.
 

Gavin John Hyde

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I have a few things I use
Before now I have taken a few bricks out and fitted a breeze block - works well when you are dealing with really crumbly old walls that a good kick would bring down. you can then use a multi tool to cut the breeze block.
Otherwise as others have said, some dry wall adhesive mixed works well. I haven't added cement to it in the past, but have added some fast setting contact adhesive! stuff dries like concrete and can take any drilling.
I sometimes drill additional holes in the backboxes to get holes in behind, works really well when the box sits across 2 bricks/blocks and only one has crumbled. you can then look to get screws on the edge of the other or even go diagonally with longer screws. coupled with some grab adhesive around box, have had no issues.
if you have a cavity behind the bricks which have crumbled, you can sometimes get a piece of timber in there, this will span the back of the hole just cut and with some nice long screws will come tight against the back of the bricks when screwed with the backbox, to get this to work you need to get one or more screws in vertically to the wall, you can then fill around edge with what ever is to hand, once set hard remove the vertical screws if you need to.
My final trick is to use a bit of metal conduit to fix into the back box, assuming your chase is deep enough( make a few wide parts if required) you can then fix the conduit in place with saddles which will hold the back box steady, then get the expanding foam out to spray in through back of the box and around edges. trim back once dry.
it all comes down to each house being different and finding what works for you.
 

Pete999

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Slap in some strong Compo to bed the box in, Compo = sand and cement in 2 sand 1 cement ratios. that'll fix the box alright if it don't eat it away first.
 
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Thanks for all these suggestions... much appreciated. It's amazing learning from the older sparks...
 
i sometimes knock the rear knockouts out, and that gives you a bigger choice of where to drill into the wall. Then use a penny washer with the screw to secure.
 

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