Possibly the worst wall I have ever worked with,

[eskimo39]

Can anyone here give me some advice? I am currently doing a full rewire on an unoccupied house but having some trouble chopping in backboxes.

All external walls are fine but the internals are a real nightmare. They are made of a kind of soft breeze but have like a large 2" cylindrical hollow running down it every six inches or so. When trying to chop in i just end up breaking through the other side and cannot for the life of me get a flat back to fix to.

Anyone have this before.

Also the customer wants rid of the pull switch in the bathroom so I was going to chop a box in but found out it is a stud. No problem I thought as I would just use a plasterboard backbox but it is Lathe and Plaster. Will a plasterboard backbox work in this? Or am I best removing a section of lathes between 2 studs and replacing with plasterboard?

Cheers

EDIT: Sorry should read worst wall not works wall.

 

[Marvo]

Re: Possibly the works wall I have ever worked with,

If the wall is those hollow blocks you can usually fix backboxes with screws through the sides if the hole is neat. Chemical anchor might also be an option but it can get messy.

 

[Electricalserv]

Re: Possibly the works wall I have ever worked with,

Can anyone here give me some advice? I am currently doing a full rewire on an unoccupied house but having some trouble chopping in backboxes.

All external walls are fine but the internals are a real nightmare. They are made of a kind of soft breeze but have like a large 2" cylindrical hollow running down it every six inches or so. When trying to chop in i just end up breaking through the other side and cannot for the life of me get a flat back to fix to.

Anyone have this before.

Also the customer wants rid of the pull switch in the bathroom so I was going to chop a box in but found out it is a stud. No problem I thought as I would just use a plasterboard backbox but it is Lathe and Plaster. Will a plasterboard backbox work in this? Or am I best removing a section of lathes between 2 studs and replacing with plasterboard?

Cheers

EDIT: Sorry should read worst wall not works wall.

I had this problem with the breeze blocks no too long ago was an absolute nightmare. Try and get a baton of wood screwed into the second breeze block and screw backbox to that.

As above chemical adhesive will also do the job if the batons fail...

 

[telectrix]

Re: Possibly the works wall I have ever worked with,

have had this problem before. some internal wall are only 2" thick. what i have tried in a couple of cases is to fit 2 boxes back to back, plaster them in with a couple of nuts and bolts through them.

 

[pennywise]

Expanding foam in the hole let it go off cut flat then fix as said before into the sides of the box to the wall, the worst walls and I hope you don't have the mis pleasure of working on them are the one made entirely of flint that have had a cement slurry pored around it huge air gaps voids and the slightest hammering dislodges most of the surrounding wall ahhhh it was hell!

 

[mnbs 4x4]

MK flange boxes fixed with inch and half sixes for the lathe and plaster wall, used to use them all the time in NE scotland house rewires

 

[Electricalserv]

MK flange boxes fixed with inch and half sixes for the lathe and plaster wall, used to use them all the time in NE scotland house rewires

Perfect for the job...expensive though.

 

[BOROROBBO]

"C MIX" is your friend here.

squirt it in with a silicone gun and let it dry. drys as hard as rock

 

[Dunc]

Bonding is great for this sort of job. Either an old bag of the stuff or mix it up with warm water to make it go off quick. Sticks like the proverbial to a blanket and if you gobbo your boxes in while you're doing it they won't even need fixings as the bonding will hold them in no problem.

 

[telectrix]

i prefer the " one coat plaster " from b&q. it sets like concrete, and you can buy it in small bags .

 

[topquark]

All external walls are fine but the internals are a real nightmare. They are made of a kind of soft breeze but have like a large 2" cylindrical hollow running down it every six inches or so. When trying to chop in i just end up breaking through the other side and cannot for the life of me get a flat back to fix to.

Cut the holes for the boxes as best you can. Use some easi-fill 20 to make good the hole back/sides and let it go off, then fit the back box as normal (trim if necessary). If you use gripfill/chemical type fixings it's a pain in the bum to take the box out later if needed.

Edit: OK that took too long to type then

 

[mogga]

if its stuff Im thinking of its likr china and an absolute bum to get boxes in due to the formers between both outer skins best bet is the bonding type plaster when your cutting in boxes and chasin Rather you than me

 

[Spudnik]

My house has these dam blocks, and i have done others with them.

I just chop the box in as normal and go through to the hollow.

Once they are all cut in, i use bonding plaster, half fill the hole, push box into plaster.

Then a couple of screws pushed through the fixing holes.

Never, ever had a problem.

 

[isitintheregs]

No problem I thought as I would just use a plasterboard backbox but it is Lathe and Plaster. Will a plasterboard backbox work in this? Or am I best removing a section of lathes between 2 studs and replacing with plasterboard?

I use BG dry lining boxes in lath & plaster walls. The tabs allow for a thicker wall and push outwards rather than hinge out. Worth a try.

 

[ian]

I come accross this often. i usually cut the boxes out then bond them in. never had a problem.

 

[rocker]

For the lathe walls I normally remove an area of the lathe and plaster larger than the boxes I want to put in, then cut a section of plasterboard to fill the hole. Screw battens into the inside of the lathe wall leaving an overlap, then screw the plasterboatrd into that. A very quick skim, wait for that to go off, then cut with your padsaw and fit dry lining box as normal. It's a bit of a faff but makes for a much stronger fix - I've tried larger boxes to fit straight to the lathe wall, but with pulling plugs in and out, they don't last 10 minutes.

 

[nickblake]

this type of block are very common round here your lucky you have an unoccupied house , its a pig when youre trying to get the power on , what i do is as has been mentioned use some bonding plaster ,do all your chases ,mix some bond up fill the hole push in and level the back boxes ,then leave till the next day , then drill and plug they are not going any where after that , the plaster would probable hold them but more proffesional if you screw them up to

 

[Amp David]

A vote here for good old bonding plaster, cant go wrong using that stuff

 

[Goody]

Did you give a thought for Liquid Nails and wooden batons?