Back Box In Hollow Wall Installation

[mackatoon]

Hi Guys, I've completed rewires with hollow walls before and was able to use a dry line Box. No chance of being able to use them this time.

I've never seen walls like this though. Just wondering how people have installed back boxes in this circumstance? I've attached a pic

I'm assuming Fire resistant Expanding foam or Plaster? Prob need the version which dries the quickest as ill need to start runnung cables asap.

Your helps appreciated

Andy

 

[SparkyChick]

It's looks like lath and plaster on the first take, but now I'm not sure... what is it actually made of?

 

[snowhead]

It looks like the hollow earthenware blocks as used in Europe.

Same sort of thing as this but not this exact one,

 

[SparkySy]

They look like clay hollow tiles to me, similar to above but with nothing in the middle! There are some houses in Meriden built with those! Complete pain to work with. They don't have much integrity once you have smashed the middle out of them so use cement or something strong to bed your boxes to give the block some of it's strength back! I don't think they are meant to be chased out at all!
The last one like that I rewired we didn't sink the box any deeper than the Plaster and then the whole house was overboarded to make up the difference!
Sy

 

[snowhead]

Closer

 

[SparkySy]

They look more like the sort of thing I was thinking of!

 

[mackatoon]

They look like clay hollow tiles to me, similar to above but with nothing in the middle! There are some houses in Meriden built with those! Complete pain to work with. They don't have much integrity once you have smashed the middle out of them so use cement or something strong to bed your boxes to give the block some of it's strength back! I don't think they are meant to be chased out at all!
The last one like that I rewired we didn't sink the box any deeper than the Plaster and then the whole house was overboarded to make up the difference!
Sy

Yeah that's exactly what it feels like clay tile, I think your spot on.

They look more like the sort of thing I was thinking of!

 

[mackatoon]

Yeah that's exactly what it feels like clay tile, I think your spot on.

They look more like the sort of thing I was thinking of!

I think every socket i need to chase in will need filling then afterwards. Jeez what a nightmare this job will be

 

[SparkySy]

They are rubbish, they were a very cheap building material though at the time!
Horrible job you may need to pre fill the void somewhat before you fit the box as trying to drill the remaining block will deteriorate it further and won't provide a fixing! Then once the box is in make good around the box and chase.
Sy

 

[telectrix]

dot & dab adhesive. works a treat. or if hole is too big, epanding foam. goo the back box in before foam cures.