Crumbling internal block work

[shockfire]

Hi all,

We have a cavity wall, where the outside is clay bricks and the inside is concrete blocks.

However, in some places (seemingly randomly throughout all 3 outside walls), the concrete blocks have "dents" in them. When placing a finger in a "dent", the block begins to crumble and the dent gets bigger. There is no sign of rising damp, and nothing "feels" wet.

Does anyone know what could be causing this problem? Searched all over but cannot find any information.

Thanks for your help ,
Shockfire.

 

[garyo]

Are the inside walls plastered, and you're seeing these dents in the plaster too, and then pushing your finger through into the blocks?

 

[Static]

Can you take some photos?

 

[cornishwizard]

if it was an old house in cornwall or devon I would say it was mondic block problem

 

[Nige F]

Flippin `eck wizard - I just googled it That is a bad scenario

 

[cornishwizard]

its not that bad as its easy to knock down

 

[shockfire]

Are the inside walls plastered, and you're seeing these dents in the plaster too, and then pushing your finger through into the blocks?

Yes, in these areas the plaster was "bubbling" on the wall. When touching the plaster, it flakes off the wall, to reveal the crumbling areas in the blocks.

Can you take some photos?

I've included one below, please let me know if you need any higher quality (was taken off a camera phone )

if it was an old house in cornwall or devon I would say it was mondic block problem

Nah it's in Hull

Any help is greatly appreciated

 

[cornishwizard]

that looks like the rendering that is crumberling not the block. dig back to the block.

 

[shockfire]

that looks like the rendering that is crumberling not the block. dig back to the block.

It's definitely the blockwork itself, can dig about 4 centimetres into it by just brushing with a finger.

My stepdad is a builder, and said he's not seen anything like it, but said it might be due to low quality blocks.

Think i'm going to have to get a surveyor in sometime!

Will keep the thread updated with the answer

Thanks
Shockfire

 

[cornishwizard]

how old is the house

 

[shockfire]

how old is the house

Not too sure to be honest, either 1940s or 1950s.