thermalite external wall

[MH731Z]

Hi Everyone

we recently removed the conservatory and foundout the walls were made of thermalite, we were told by a builder this is wrong and the fix would be expensive.

I'm getting all kinds of quotes and opinions about this so really at a loss here as to what to do, I'm thinking the DIY way but I have some questions and would appreciate any help!

the idea is to remove all square tiles and close that opening then continue the red tiles so its all like the photoshopped image attached, my questions are

1. do i need to seal those blocks with something before applying rendering ? if so what seal should I use ?
2. how can I safely remove the white tiles and tile adhesive without damaging the air blocks ?
3. it seems the wall behind the red tiles is all timber and the whole first floor loft conversion/extension is all timber, do I need to add some sort of membrane before I add the battens to hold the clay tiles ?
4. is there a better way to do this ? one quote I got was for £8k another for £3k without materials...


any insights or ideas are much appreciated!

 

[noseall]

Hi Everyone

we recently removed the conservatory and foundout the walls were made of thermalite, we were told by a builder this is wrong and the fix would be expensive.

I'm getting all kinds of quotes and opinions about this so really at a loss here as to what to do, I'm thinking the DIY way but I have some questions and would appreciate any help!

the idea is to remove all square tiles and close that opening then continue the red tiles so its all like the photoshopped image attached, my questions are

1. do i need to seal those blocks with something before applying rendering ? if so what seal should I use ?
2. how can I safely remove the white tiles and tile adhesive without damaging the air blocks ?
3. it seems the wall behind the red tiles is all timber and the whole first floor loft conversion/extension is all timber, do I need to add some sort of membrane before I add the battens to hold the clay tiles ?
4. is there a better way to do this ? one quote I got was for £8k another for £3k without materials...


any insights or ideas are much appreciated!

It's nigh on impossible to remove well adhered strong gear, from aerated blocks, without damaging them. You may even dislodge those at the top of the wall, closest to the tile hanging. You need a modestly weighted SDS pecker (SDS drill with roto-stop) and a broad bolster chisel and a skilled operator.

Just be thankful you are not removing gear from both sides of one leaf of aerated masonry. I've seen these walls destroyed this way. We never build with them any more. Absolute tat.

 

[^woody^]

Why can't you batten over them?

 

[MH731Z]

It's nigh on impossible to remove well adhered strong gear, from aerated blocks, without damaging them. You may even dislodge those at the top of the wall, closest to the tile hanging. You need a modestly weighted SDS pecker (SDS drill with roto-stop) and a broad bolster chisel and a skilled operator.

Just be thankful you are not removing gear from both sides of one leaf of aerated masonry. I've seen these walls destroyed this way. We never build with them any more. Absolute tat.

@noseall thanks for your advise, its shocking to think this stuff was ever even allowed!

Why can't you batten over them?

@^woody^ the level of the tiles is thicker than the white rendering so if I batten over it it will come out by about 15mm, however I'm thinking if i do this how can i the two levels be joined ? ie the clay tiles on top and the lower clay tiles will be on different levels ?

 

[MH731Z]

also can thermalite be drilled ? how would I secure the battens to it ?

 

[Koolpc]

It can be drilled but it can be a nightmare.

 

[^woody^]

also can thermalite be drilled ? how would I secure the battens to it ?

Use spiral nails - helical bar.

 

[^woody^]

If be inclined to chip the tiles of with a sharp bolster - hand would be just as easy as a SDS bit.

Mark the battens out and concentrate on those lines.

 

[MH731Z]

If be inclined to chip the tiles of with a sharp bolster - hand would be just as easy as a SDS bit.

Mark the battens out and concentrate on those lines.

I think I'm gonna go with this option, so basically as follows;

1. gently remove the tiles but not the back tile adhesive
2. remove more of the clay tiles to expose the battens
3. extend those battens using spiral nails or anything compatible with thermalite
4. render the exposed thermalise on the sites with cement or any other rendering

question though, how tolerant are those wall/clay tiles to uneven levels as where the new battens will be and where the old ones are there's probably a 10mm depth difference, the new battens being 10mm over the old ones if that makes sense.

why this material hasn't been banned is beyond me... I think the previous owner made an opening at the back of the house and just used it rather than brick it, if i had the money I'd get it all redone with brick or block

 

[Ivor Windybottom]

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