Autoclaved Aerated Concrete Failure - Residential Buildings Affected?

[blup]

From what I understand, part of the issue is that “normal” concrete is waterproof, but the RAAC is not. (Or at least more susceptible to damage)
If built to the intended standard and maintained, it should be covered in a high quality roofing material to prevent moisture.
However budget saving patching has resulted in the panels getting wet due to delays and cheap coverings.

The moisture affects the RAAC more than a solid concrete panel

At leat that’s what a guy on the radio said.

That's about right.
Water gets in.
Crumbling, freeze-thaw, etc.
Rebar corrodes.
Add this is the fact that "soggy" concrete is a lot heavier than dry, aerated, and this is why it's a problem.

If that's correct, the manufacturer and installer will have zero responsibility. More likely those responsible at local authority level or academy/trust level for not maintaining and passing on records of construction, or carrying out proper surveys of condition. You can see a situation where the responsibility for the school has passed from LEA to trust, but none of the expertise and knowledge that goes with it because they have all retired or been made redundant. And the school trust has none either.

Blup

 

[motorbiking]

This thread seems to have the sensible debate on the subject. The issue is when if absorbs water and the reinforcement bar corrodes, leading to loss of strength. Probably quite tricky to see which blocks have been weakened and which are ok.

I remember when glass roofs were popular at airports and offices occasionally the glass would fall out due to expansion and thermal conductivity of the aluminium frame.

Happened at my old office. Fortunately nobody hurt.

 

[Ivor Windybottom]

Think I'd rather be showered in safety glass than concrete though.

Just another lesson in why we'd be much better off sticking to conventional construction, mostly made by stacking stuff on top of things, with lumps of tree to hold the roof up. Every alternative seems to end up having massive issues. Probably most of the current shiny modern things will end up the same way for one reason or another.

 

[blup]

Roofs fail, it's no different in principle from a cold roof failing for lack of proper ventilation. There is a difference between a domestic flat roof gradually failing, and a concrete roof collapsing on a class of school kids. But both can happen because of incorrect installation and/or maintenance.

Blup

 

[Brigadier]

Roofs fail, it's no different in principle from a cold roof failing for lack of proper ventilation. There is a difference between a domestic flat roof gradually failing, and a concrete roof collapsing on a class of school kids. But both can happen because of incorrect installation and/or maintenance.

Blup

Agreed, but

Your typical cold roof lasts what, 50 years?
Closer to 100, if clay or slate-tiled?

And in non-domestic settings, low likelihood of anyone farting around with the roof, and knackering the ventilation.

Flat roofs are inherently a crap idea, even if perfectly installed.

 

[Justin Passing]

It's predominantly flat roof "planks" which are the problem. They've been used since the 50's, and were expected to have a 30 year life. Well it's only 70 odd years, so why on earth should there be a problem...
There have been warnings since the 90's.
Fitters often didn't use a long enough bearing distance (some were specc'ed at 45mm but the planks didn't get it)
The design is crap, it's asking for failure.
The stuff is effectively porous, hence its weight increases a lot due to the amount of water it holds.
And the thermal insulation thereby fails.
The surface cracks and spalls and plants grow.
Where there's reinforcement, the bond to the concrete fails - small movements crunch it.
Yes the steel will rust .
All concrete weathers - rain is slightly acidic, and it has an effect on the chemistry. The pores join up.
People walk on roofs when they shouldn't, people drill holes through it, and on and on.

Plain dumb design and heads in the sand.

 

[Notch7]

The problem is this has been ignored and ignored until it can't be ignored anymore.

Two schools have closed. The third school that is my daughter's have had the temporary marquees put up for until the more permanent temporary cabins will be installed (not my words). So they will be ok. The two primary schools are not so fortunate.

It’s a major worry for parents.

 

[fillyboy]

Plain dumb design and heads in the sand.

But in the 50's when a there was a demand for fast, cheap buildings, quite innovative.

 

[securespark]

Labour had plans to fix these school issues that could have been completed by 2020.

If Labour get in, they'll make progress on fixing these issues and no doubt the Tories will be slamming them at every opportunity.

Then if the Tories get in in the future, they'll be shouting from the rooftops about how badly Labour have done.

Sadly, as we have seen over the last 7 years, if you spout shoite long enough and loud enough, some people start to believe it.

 

[securespark]

But in the 50's when a there was a demand for fast, cheap buildings, quite innovative.

I believe the geezer who designed the Liverpool Cathedral came up with plans for prefabs.

 

[gant]

Labour had plans to fix these school issues that could have been completed by 2020.

If Labour get in, they'll make progress on fixing these issues and no doubt the Tories will be slamming them at every opportunity.

Then if the Tories get in in the future, they'll be shouting from the rooftops about how badly Labour have done.

Sadly, as we have seen over the last 7 years, if you spout shoite long enough and loud enough, some people start to believe it.

The Impact and Legacy of the PFI in UK Schools

As the attraction of public-private partnerships has waned, a combination of different investment models is now favoured.

politicalquarterly.org.uk

All these commentators with the use of Google and no idea of how the building industry has worked over time comment and display their complete lack of knowledge.
An instance would be Ronan point, bonus being introduced, the collapse of carrilion etc etc.

 

[securespark]

I believe the geezer who designed the Liverpool Cathedral came up with plans for prefabs.

It was Frederick Gibberd.

 

[blup]

The Impact and Legacy of the PFI in UK Schools

As the attraction of public-private partnerships has waned, a combination of different investment models is now favoured.

politicalquarterly.org.uk

All these commentators with the use of Google and no idea of how the building industry has worked over time comment and display their complete lack of knowledge.
An instance would be Ronan point, bonus being introduced, the collapse of carrilion etc etc.

Google says pfi is posh name for debt, which was funded government bonds. As was lockdown.

Blup

 

[fillyboy]

I believe the geezer who designed the Liverpool Cathedral came up with plans for prefabs.

And what a great plan it was.

Prefabs | Historic England

historicengland.org.uk

 

[blup]

They even made vegetables from concrete

Blup