The Ugly Truth About Reinforced Aerated Autoclaved Concrete (RAAC)

Read Roger's article on Reinforced Aerated Autoclaved Concrete (RAAC).
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RESOURCES
Information on Reinforced Autoclaved Aerated Concrete (RAAC)
🔗 shorturl.at/adoHZ
GOV.UK RAAC Identification Guidance
🔗 shorturl.at/uHT28
Structural safety of reinforced autoclaved aerated concrete planks
🔗 shorturl.at/rFQT2
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ABOUT RAAC
Reinforced Aerated Autoclaved Concrete (RAAC) is a specific category within the family of lightweight concrete materials. Let's break down the components of its name to better understand its properties:
Reinforced: Like many concrete types, RAAC can be reinforced with steel bars or mesh to increase its tensile strength and structural capabilities. This reinforcement allows the concrete to withstand forces and stresses that it couldn't bear on its own.
Aerated: Aerated concrete contains many small air pockets or bubbles, which are introduced during the manufacturing process. These air pockets make the material much lighter than traditional concrete and provide it with good insulating properties. The air pockets are created by adding a foaming agent to the concrete mixture or by a chemical reaction between certain ingredients.
Autoclaved: Autoclaving is a process in which the concrete is subjected to high pressure and temperature inside an autoclave (a type of large industrial pressure cooker). This process accelerates the hardening of the concrete and enhances its strength and durability. Autoclaving also results in a more consistent material with fewer defects.
The advantages of RAAC include:
Lightweight: Because of the air pockets, RAAC has a lower density than traditional concrete, which can lead to savings in transportation and construction.
Insulating properties: The air pockets in RAAC provide it with good thermal insulation, making it suitable for use in energy-efficient building designs.
Speed of construction: RAAC panels and blocks can be manufactured in large sizes, allowing for rapid assembly on site.
However, RAAC also has some limitations:
Lower strength: Even though it's reinforced, RAAC generally has a lower compressive strength compared to regular concrete. This means that it may not be suitable for certain structural applications.
Sensitivity to moisture: RAAC can be susceptible to moisture penetration, reducing its lifespan if not properly managed or protected.
Despite its advantages, RAAC has seen a decline in popularity in some parts of the world due to concerns about its long-term durability and incidents where failures occurred. If considering its use, it's important to consult with professionals familiar with its properties and potential limitations.
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#concrete #construction #reinforcedconcrete
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[@AW-xj4un]

I’m a Chartered Engineer and it worries me how pretty much everything is built for the lowest possible cost. Not just buildings, but also cars, machines, electronics. It’s a great explanation and it is the ugly truth.

[@eddievanbasten1751]

£18.5 billion to refurb the Houses of Parliament, £370 million already spent on the refurbishment of Buckingham Palace. Oh, and however much Ukraine wants on top.

[@ksptm4]

I’d argue if you’re a chartered engineer, then you have the responsibility to ensure specifications is met, along with the ER’s and to ensure you don’t value engineer it based on bottom line. Too often I’ve seen consultants buckle on their own specification and allow a project to go from spec driven quality to contractor led d&b. In short, consultants and contractors are both as bad as eachother.

[@cornishhh]

I'd argue that cars are just ridiculously over complex.

[@damianbutterworth2434]

The accountants rule. I work for an Italian company and they are opposite. They built us a new factory with underfloor heating, automatic windows. Granite tiles in the toilets, automatic doors, taps, toilet flush is even automatic.

[@derekjc777]

As a Chartered engineer I know there are building regulations and design standards for everything from silicon chips to cars and trains. This means that the cheapest should meet the minimum standards and be safe. I also know that sometimes buildings are built substandard and that supplied materials are either substandard or are found later to be dangerous in one way or another. RAAC and asbestos are two examples. Flammable panels that do not meet UK regulations that were still fitted to high-rise buildings, like Grenfell Tower and Lakanal House, are another. The worst example is our porous border after Brexit and the likes of Amazon market place letting through substandard food and electronics, rotting meet from Eastern Europe and Asia, and AC-DC mains adapters that short and burn down houses, along with badly-sealed lithium batteries that absorb water and explode, from dodgy factories in China. After Thatcher’s and the EU’s deregulation drive (cutting red-tape and “better regulation” sound much better than building more dangerous buildings or making more dangerous electronics) we have seen standards erode rapidly over the last 40 years. One example is fire brigades no longer being responsible for checking the fire precautions in buildings. Brexit and post-Brexit trade deals have only made things worse. Many of these regulations were the results of accidents and medical disasters, from Thalidomide to asbestos, lead in petrol and paint, and now air pollution from burning fossil fuels. We take too long to ban dangerous substances and practices because corporations make large profits from selling and using these materials, and are reluctant to share those profits with consumers and residents who suffered or died from their use. So it’s a mixture. Standards are good and the cheapest should still follow the standards. But they’re not updated quick enough and the manufacturers of dangerous substances - who often know of the dangers decades before consumers - are not punished hard enough. Regulations are not enforced well enough, and there are not enough investigators to check they’re being followed. Bring back the red-tape I say, and put people before profits.

[@terencewhite8105]

Having worked for a National builders merchant for over 30 years and attended many courses and manufacturers visits ,also having supplied many of these floor and roof slabs over the years,rightly as you say not just in schools,blocks of flats a good example it is a joy to actually listen to someone who knows what he is talking about on this problem rather than the so called experts on all these media channels and newspapers

[@piccalillipit9211]

Im not an expert, but as an author I did the usual thing and spent 2 days reading the technical and scientific reports. I am amazed by the vast number of internet RAAC experts and people on TV who seem to have read nothing.

[@eddievanbasten1751]

The news and media channels only have spokesmen on that speak their narrative.

[@stephenrice4554]

The curse of the internet , poor information, easy access , lazy ' experts' , and the majority gullible enough to believe what they get from the magic box .

[@minmogrovingstrongandhealthy]

Father was a construction worker at one point in his life, he complained that some of the materials are harmful even with protection and the way they do things is wrong. He was told that he is paid to work and not to think. 5 years later he got lung problems and other medical problems following up, he couldnt do anything anymore got fired. He suffered for about 15 years, became homeless 3 times, was in prison 2 times and died from lung cancer this year. I inherited all his remaining debts which were more then half a million euros in total including his funeral and all other expenses and these new bills keep on arriving on my doorstep, if I dont pay I go to prison and lose everything I have just like him and bunch of others, collectively with that move now they want to kill me too with the same flawed systems my father was killed by. This is a problem in Europe, UK, USA and probably some other places that I don't know of yet and it all came with the USA invasions, before that we never had these problems and people had an actual life before USA and bunch of other fake countries and similar crap even existed. The typical agenda create a consumer, milk it till it croaks, make things break, milk it with botched works or empty promises, repeat ...

[@alfoz6547]

Another outstanding public information broadcast by the main man Roger ! Why can't the people that have the most common sense and expert knowledge on a wide range of subjects beneficial to us ,the general public, run for office in government? If all the working class brilliant minds were to form a political party you'd win every election going !! Well done Roger, and the skill builder channel....you've got my vote 👍!!

[@PaulSmith-pr7pv]

Roger for Minister of Common Sense

[@grommile]

"Why can't the people that have the most common sense and expert knowledge on a wide range of subjects beneficial to us ,the general public, run for office in government?" Among other reasons: Because they don't *want* to. This is why some people think we should replace elections, where people who want to be in Parliament try to persuade us to vote for them, with a system where people are randomly selected to sit in Parliament for a fixed term and aren't allowed to refuse. Those people are strange, but I understand where they're coming from.

[@allislove9890]

Plum chum jobs for big lying egotists mostly - they threw Alan Bridgen out for asking common sense questions - because our government all too greatly resembles "The Wizard of Oz." How people with no relevant qualifications or experience in a particular field can be appointed to ministerial positions is utterly ridiculous.

[@arpadvarga3475]

All those politicians say they used it because it's cheap....not bloody cheap if you have to build a new school in 30 years time 🤯🤯🤯

[@LoremIpsum1970]

How would they know in advance 30 years ago? It's industry-wide and I guess contracts are awarded on the lowest costs as well...and it's not limited to schools. It's a bit like the cladding debacle when you add the media to this issue...

[@guyemmott4009]

Exactly 💯 % Short-term solutions for electoral votes.. totally ignorant administrative government officials! 🤬

[@LoremIpsum1970]

@@guyemmott4009 ...so that's the local authorities planning offices and building inspectors...who aren't voted in...

[@mgsp5871]

obviously if the roof is always tight it may last 100years or more. As always a building is just as good as it's roof. Here the saying is the lifetime of a roof is the same as it's angle

[@jugganaut33]

Yet they knock down the public Victorian school houses that aren’t Eton. And replace them with this shit

[@mlawlan69]

"architects mincing about, lets just build the bloody things" had me in stitches 😅 Truer words were never spoken.

[@gdfggggg]

We need more masculinity, I miss it. I remember when I was a mechanic I went into work with my shorts on and one of the older guy shouted out, ‘oy, what’s those two bits of cotton hanging off your shorts?’; he was taking the mick out of my skinny legs, ha ha. The good old days.

[@simonwaldock9689]

I remember my grandfather who was a civil engineer telling an architect; "you can't build that," "why not?", "it will fall down". The building wasn't built like that.

[@mattmullender7922]

Brilliant explanation! If only the politicians could be this pragmatic, maybe the local authorities wouldn’t all be going skint!

[@leegosling]

If only the maintenance budgets hadn’t been slashed by Westminster, removing the ability for local councils to keep it all in good nick… bloody councils though… 85% of the councils that have a problem with this are the ones that politically were aligned to the austerity programme and did not reallocate funding to maintenance. Gove took the money away and it was inevitable that this was going to happen… bloomin Tory Councils, eh? Same for asbestos… once maintenance stops the problems arise.

[@julianshepherd2038]

I think you will find it more complicated than that. Are you 15 y o

[@davidelliott5843]

Local authorities love their mega project and always jump on bandwagons. Then they always cut corners on “trivial” stuff like maintenance. RAAC is just the latest. High Alumina Cement (which rots steel) is another.

[@davidelliott5843]

The latest school build in my town is a timber frame with glulam beams. It’s no mega project, but it went up in no time and it wasn’t a silly cost. Sadly it does have a flat roof but at least there’s no fancy concrete to spall and crack.

[@mattmullender7922]

@@julianshepherd2038 Silly me for not using the comments section of a KZbin video for a ‘deep dive’ into the extent of the ineffectiveness of local government!

[@marcoholt1847]

Thanks Roger, as always 10/10 for information and entertainment, perfect to brighten up my Sunday morning housekeeping. Ps am also a Chartered Mechanical engineer and never see any technical faults in your videos.

[@SkillBuilder]

Thanks for the comment. I am sure I do get things wrong but I am happy to have so many viewers putting me right

[@droptop44]

Nobody has explained anything like that on the tv, excellent work.

[@truefoa]

Excellent video. These are the kind of videos we need when people see something on the news and go looking for answers instead of the politicians explaining it.👍

[@Richretired1945]

I have shared this brilliant video to my Facebook feed for all my friends to see 👍👍

[@SkillBuilder]

Thank you for that.

[@gdfggggg]

If we listened to anything politicians say we’d be truly F….

[@Crossley10]

I went to Fairfields school in Basingstoke, built in 1884, still in first class condition today. It was the pride of the town at the time of its birth, Surely there is no reason why we cannot build schools and hospitals today that will last several hundred years. Obviously they would be refitted as and when to meet the current needs, but the basic structure would remain.

[@argonauth]

The costs of retrofitting are huge.

[@geoffhaylock6848]

@@argonauth Not if the building was built right in the first place. Classrooms, library's, halls how do they change much? They will need decorating but that must be cheaper than replacing the roof every 40 years and worse still, putting children's lives at risk. The Victorians must be looking down at us laughing. We can't even build a safe school anymore.

[@argonauth]

@@geoffhaylock6848 when I first come to UK, I started working on the project of an hospital unit. As the project some some 10 years hold we were making 1 out of 2 surgery rooms, as the ammount of machinery has increased a lot but the speed to conduct surgeries highly doubled. Look at how the insulation and ventilation requirements has changed and you will see the cost of retrofitting. The structure is only 1/5 of the cost of such building.

[@jordanguyy]

You sir deserve a medal well done honestly absolutely superb video more like this please mate. 🙏

[@derekhawthorne2245]

Absolutely well explained. We had the same with HA C remember Spghetti Junction on the M6 beig closed. ? 21:05

[@triedzidono]

Does Roger Bizby have an OBE yet? he's doing more than any foot & ball player

[@dolceanstar]

This is the best video I've seen on youtube in years. Brilliantly presented by a knowledgeable and experienced skillsman.

[@martinmorris8862]

The mad thing is that RAAC was withdrawn from use in the mid 90’s because it was discovered in the 80’s that it suffered cracking & unlike reinforced concrete RAAC is no where near as strong. Many people have heard the term concrete cancer and as you have described that just what’s happening in part. Rebar rusts expands resulting in RAAC failure. Moisture is another huge issue. As it was announced 30+ years ago & common knowledge RAAC only has a 30 year life span it was plain and obvious this should have been dealt with and removed. Thousands of schools and thousands of other buildings were built using RAAC that should have all been replaced decades ago & it would have been far cheaper than it will now. Crazy world no excuse for this negligence . Many buildings have false ceilings so checking is not so easy. Yet all councils & Gov should know where it was used. Yes Asbestos is another huge issue. Many of the suspended ceilings we installed were to shield from Asbestos dropping. RAAC is all past its user life and been highly dangerous for decades . So far in Scotland over 35 Schools have been identified with RAAC that number will no doubt be in the thousands.

[@Me-zo8yc]

Couldn't they just re-roof the building? (I know it's nowhere near as simple as just saying it)

[@martinmorris8862]

@@Me-zo8yc NO, its also used as flooring and walls & cladding. The issues should have been dealt with decades ago & its just a complete cockup. Even as late as 2018 where a school roof fell in nothing was done yet they still knew that from the report in the 80's RAAC only had a 30 year life span. Building built from the 1950's to the mid 1990's where it was withdrawn from use are all well past safe. It comes down to not wanting to spend money and pushing it out of sight , out of mind. Its not just schools, collages, hospitals , council & civic building its also offices its homes, like council housing, high rise buildings built in those periods probably also used RAAC. I listened to an MP the other day saying teachers should fill out a survey after inspecting the schools for RAAC. That is the incompetence of the MP's they are clowns. It will be a very long and a very very costly fix

[@Me-zo8yc]

@@martinmorris8862 I see, thanks. 'Buy cheap, buy twice' it is then.

[@johnclements6614]

@@Me-zo8yc It maybe possible to remove the raac panels in a roof and put on a new roof made with timber trusses etc. Altering buildings can be difficult as you do not know what you are going to find until you start removing things.

[@srp01983]

@@martinmorris8862The problems with RAAC are different to ‘concrete cancer’. While the end result (failure) may be the same, concrete cancer is a reaction between silica and alkali, which causes expansion of the concrete and a network of micro-cracks, reducing the tensile and compressive strength of the concrete. It may result in the ingress of water and corrosion of reinforcing bar, but it is the reduction in the strength of the concrete which is the mechanism of failure. But I have no problem with your comments regarding the seriousness of these problems, or with the fault of the government for the lack of both investment and competence.

[@bobo3034]

Brilliant video. As an ex owner of a flat roofed commercial building, I can confirm that no matter how well constructed, sooner or later, water ingress will occur. Over a period of time, it cost more trying to cure the water ingress, than it would have cost had we had a pitched roof constructed in the first place.

[@esecallum]

Put a slanted PVC panel on top

[@navmohindra579]

Thank you skill builder for making sense of the new scandal. You seem to be the only one that has the intelligence to give a great comprehensive breakdown of RAAC 👏🏼👏🏼 Carry on the great work!!!

[@anthonydavies6021]

What a brilliant guy! All education ministers should be schooled (!) by him before they go anywhere taking responsibility for the buildings that our dear children study in (ignoring the equally shocking discrepancy between private and state school buildings).

[@nlwilson4892]

Really good suggestion of having one design for schools to cut down on design costs and get the best design that works. In order to fit in with the needs of the area there might have to be a few models (some single storey, some 2 storeys, different from primary and secondary etc. But a few designs done in such a way the number of classrooms can vary would be very workable and much needed.

[@ChrisCooper312]

It's also something common in many different building types. A lot of chain businesses that use new builds have standard designs for their buildings, with variations based on the needs of the particular branch. House builders tend to have common designs, but again with variations for different property types. It's not new either. The railways were an early adopter of it, and you see a lot of stations built by the same company that are variations on a common design. It not only cuts down on design and building costs, but also maintenance, since parts are more common. It's another reason why Aldi and Lidl work well. Pretty much anything that's likely to break and need replacing during the lifetime of a shop is identical throughout the business, so they can keep a supply in stock, or just put a repeat order in for more. Layouts and equipment are also very similar so staff can transfer around the business with ease. Where I work I often travel to different locations and one of the first questions I have to ask is where things like the canteen, toilets and offices are since no two locations are alike. Even the two brand new builds I've been to are quite different in layout.

[@frankcooke1692]

Yeah I think you could get enough variety out of some kind of modular design. How many schools do you ever go into anyway? Most students will only ever set foot in two or three different schools. Nobody would particularly notice they all look the same. There's also room for non-structural, aesthetic variations like fascia or landscaping. Demountables are already very common as classrooms - they're fine really, at least they're air-conditioned.

[@clivejohnson6468]

7:10 The water getting into the block, the weight will also increase significantly and so go beyond its "designed for" self load.

[@SaxJockey]

Saw a demo on TV recently that showed a wet aerated block is weaker in compression. Interesting to consider how a typical two storey inner course of thermolite blocks would fair in a house if exposed to a water pipe leak in the upper storey? Would the lowest blocks suffer?

[@eduardocarvalho1547]

Hi Roger I live in Portugal and I can bet the stock video at 5:06 is from a Portuguese school!!! Yes, those roofs had asbestos, as these schools were made in the 80's and 90's with "fibrocimento" tiles. These days most of them had the roofs replaced with insulated roofs and also new windows, etc. The structure at least was well built with reinforced concrete columns and beams, prestressed floor slabs and exterior double walls with ceramic blocks and cement mortar. Us kids would sometimes break the asbestos sheets with rocks, how naive we were back then!

[@alan2804]

Another excellent straight talking video Roger. I agree with everything you’ve said. Flat roofs no good, standard designs for buildings is a no brainier but wouldn’t allow money to be siphoned off by architects and councils. Politicians talk shite. And finally why can’t the UK build or do anything that works or is within cost? HS2, nuclear power plants, bridges, roads, upgrade railways, tram systems, illegal migration and many more, they (those in charge) are incapable and incompetent maybe corrupt in every large scale project. The thing these people seem to be good at is avoiding paying their share of tax and using accountants to help them. What a country.

[@DerekHart-g3t]

My infant and primary school was brick built with a slate roof put up in the early 1900s. It still stands and whilst it is far from energy efficient it is safe. My grammar school was built in the 60s and was thrown up. Two walls of every classroom was glass (single pane). This made it very cold in winter and unbearably hot in summer and whilst it is still operating it has cost more in repairs, new window frame and flat roofs than the original cost, but at least they have somewhere to put the solar panels. As kids we used to put our feet through the asbestos panels that lined the walls and pull out the fibreglass insulation for use as itching powder. Great idea to have a standard design. A few years ago my council built a Gaelic School (yes I am now in the Highlands). The architect specified stainless steel cladding on all exterior walls. It cost a fortune but was a true land mark. Now it's an eyesore because of the weather staining on the panels.

[@gordonmackenzie4512]

Lochaber High School always reminded me of the Soviet Union, as seen in the movies. Grey, dull rectangular design. Some pretty poor architects in the 60s. Those concrete boxes next to the Castle in Inverness are shocking.

[@SkillBuilder]

Yes there is some very disappointing architecture from that period.

[@Mole-Skin]

There are very few materials that can withstand the onslought of exposure to ...WEATHER..! Heating, freezing, wet, high wind, subsidence..Tsunami.. etc etc Steel will rust.. Concrete will crack.. Timber will rot.. There is no single answer.. Monitor and Manage is the credo..

[@Jonathan_Doe_]

That might have been fluffy asbestos in the walls, not fibreglass 😬

[@DerekHart-g3t]

Definitely fibreglass, fluffy asbestos doesn't have the itch factor, at least not on the skin.@@Jonathan_Doe_

[@wm6204]

Great explanation. I would like to add a peenith to why the ends went up. Since I became a carpenter and before it, I've noticed the practise of not having an adequate break between wall and roof. As a kid it was achieved with, for instance a 6"x 1" Tan with a angled triangular 2x2 connected together and the Roof itself but NOT the wall.later an aluminium section was used pre made. Flashing laid over this, leaving a water tight finish allowing abit if give. Everywhere I go now is directly attached to the wall which moves differently causing cracks where they meet. So the ends determination is in that area in my opinion down to cracks appearing in this area. Flat roofs only have a poor shelf life but pro active surveys would prevent this stuff.. Atb William

[@realbrass]

Genius. Roger you have a unique way of expressing yourself clearly, accurately, honestly and sincerely. This video is no exception, a great piece of work. Thank you.

[@nickhickson8738]

Always rely on Roger for clarity.

[@riveness]

Excellent video. As a chemical engineers, was glad to aee the production and then the explaining (new for me) in its use and downsides. The replacement program was effectively cancelled by austerity. This program was on track to be completed by 2023. Agree with standardisation, and if you need an arty piece, do it on the entrance way or put aside one building. You can have two or three design choices.

[@keithvause3733]

Its nice to hear someone who actually knows what he is talking about explain the issue with RAAC. Thank you.

[@des6106]

Amazing explanation why haven't the BBC ITV SKY CHANNEL FOUR ETC ETC ETC invited you on to inform the nation end off. Then the nation can realise that this needs sorting asap this is our future we need to look after our kids.

[@paula622]

Remember when the government used mainstream news channels to gaslight the nation during the covid pantomine...they do not care about the kids

[@eliotmansfield]

“Architects mincing around”😂

[@callibea]

Thank you for clarifying & offering common sense to the subject. This needs to be shared with all the politicians.

[@themekfrommars]

I live in Switzerland where they know about concrete and chemistry changes. It is quite common to see old concrete structures (like the foot bridge at my local railway station) be stripped down to their rebar-reinforced core using pneumatic drills, and a new outer is cast in-situ. No doubt making it good for another 40 years. I have never seen this in the UK.

[@monteceitomoocher]

Big difference here, Switzerland is well organised and its left hand knows what its right hand is doing, and understands the value of preventive maintenance.

[@Atari-stfm]

They actually do it using high pressure water believe it or not. I know people that worked on j6 in Birmingham. So yes they do do it here.

[@juliegale3863]

Excellent explanation. A copy should be sent to every politician,local and national.

[@Keith12001]

Brilliant video Roger and the team. Thanks for sharing your knowledge to all as you always do. You and your colleagues give great education, in a detailed but concise and understandable way.

[@smannick]

Great video, speaking as a structural engineer!

[@SkillBuilder]

Thanks 👍

[@danielmarshall4587]

Many many thanks for your time and effort making another SMASHING VIDEO. I don't work in your industry, I am however blue-colar and your words of "anyone who's interested" and "the job done right" RING IN MY EARS. Very much appreciate your vid thanks again.

[@Hertog_von_Berkshire]

Thank you Roger. This is precisely the discussion I've been seeking for the last few days. Journalists seem to know diddly-squat (as ever).

[@mrmyorky5634]

A clear and waffle free explanation of what RAAC concrete is all about by a chap who clearly understands the building trade. Thank you Roger.

[@SkillBuilder]

Thank you

[@jolyonroe824]

What did the Romans ever do for us - love it. Excellent summary

[@KopCole]

Well here’s a vid I never thought I’d be watching on a Saturday evening

[@cypeman8037]

One of your old videos, two years old, popped up in my feed the other day. It was about cracking aerated blocks. 🤔

[@Droningonuk]

Same here fibolites are the way forward

[@davelangford2439]

Thank you for speaking the truth about Gove scrapping the Labour policy, i wasnt expecting that from you, this is the first video ive seen of yours, I loved it! I'll be watching more!

[@brickbybric]

Concrete levy just begun in Ireland at the rate of 5 percent to pay for all the defective houses that contain mica in the blocks and pyrite in the under floor fill . They wanted to introduce it at the rate of 10 percent . It covers readymix concrete and concrete blocks.

[@amazing451]

Can you please tell me is this levy chargeable to all taxpayers in Ireland or just homeowners ? Many thanks.

[@brickbybric]

@@amazing451 it’s chargeable on the first sale of concrete blocks or readymix concrete . in the case of ready mix concrete ,if your running a precast concrete products business and buying in readmix concrete to manufacture precast concrete products like lintels ,kerbs , wall coping ect the levy is not applied . But if your building a house and you buy ready mix concrete for foundations ect the levy will apply . The first purchaser of the concrete blocks or ready mix pays the levy . So if a builders merchant buys a thousand concrete blocks from a concrete block manufacturer the merchant is charged the levy by the manufacturer. If a house holder buys a thousand blocks direct from the manufacturer the house holder is charged the levy . The levy only appears on paper work once at the point of first purchase . If your a merchant you recoup the levy as a price rise when you sell on the thousand concrete blocks or you may opt to absorb the levy if you don’t want to raise the price of the blocks . If you recoup it as a price rise you raise the price of the blocks by 5 percent and vat at 13.5 percent is added to the purchase price which includes the 5 percent price rise .

[@LoremIpsum1970]

Oh no, the whiteboard took me back to my Civ Eng course...and yes, an inch can make all the difference! In my primary and junior schools, half our time was spent in portacabins...no harm done. Politicians: "What I said were the facts as I knew them at the time..." ...They're Teflon-coated 🤣

[@phils2180]

We've seen something similar to this years ago with the use of High Alumina Cement in numerous buildings and structures and the ensuing rectification work at great expense after some buildings collapsed and suffered other structural failures. I remember the viaduct on the M1 near Sheffield undergoing remedial work for several years in the late 70's, early 80's.

[@neilcaudwell2751]

Love the reference to Life of Brian at the end.

[@slowcatto]

Your video should be compulsory viewing for all politicians. Excellent.

[@afctaylor12]

Funny what you remember as kid in year 2 I remember them say the door had asbestos. Are janitor who also ran the Beaver club was dealing with it . By the time I got to year 8 he was dead. He worked at school most his life what I was told he was in his mid 40s when he died of lung cancer. I never really connected the dots until today. Just show what you think is safe today isn't in 20 years time

[@stevejagger8602]

Your last few comments sum it up very well. Say no to flat roofs!

[@lhfloors]

Nice one Rodger you forgot to mention all the offices and high rise flats too

[@SkillBuilder]

The offices aren't such as problem beause everyone works from home now. I was in the City of London last week. It is a ghost town.

[@Jules_Diplopia]

I caught this video be accident. But you have a great style. And my father was a bricklayer, back in the 40-70s. He had similar attitudes to flat roofs, he always said that maybe they were ok in Mediterranean countries, but in rainy countries they were a disaster in the making. He would have like you. And thanks for explaining the RAAC issue to a simple non technical person like myself.

[@TimCutts]

Really informative video. Thanks very much. Completely agree about flat roofs. In a country with as much rain as here, they really make no sense. And yet almost everything seems to be built with them these days. I live in Cambridge, and all the hundreds of flat complexes going up everywhere - almost all of them have flat roofs. Quite apart from the aesthetics (or lack of), there's going to be all sorts of trouble with them in a few decades.

[@rasklaat2]

I knew about that aerated concrete blocks being used for walls and it seemed a very good idea. They are very lightweight (easy to transport and lay) and have insulating properties as well. I would never use this material for structural elements though. It's weak af.

[@Avrilmaep]

I grew up in the concrete jungle of Sheffield, park hill, Hyde park and kelvin flats that was the original concrete utopia.. park hill was built so strong with no ariation but still had some rebar, Hyde park was up on top of one of our hills that suffered from wind pushing the tolerances too much, then kelvin flats was built that did suffer from concrete cancer cos they made it from airiated concrete which had to be pulled down before it fell, the unfortunate thing was the community was lost xx

[@gwenscoble6229]

I remember my Dad (an architect) won a competition to build a hospital kitchen and I saw it being built in the 70s. Sure it used concrete, he designed an inwards sloping roof to naturally vent the heat and let in light. (No there was no pool, ornamental or otherwise in the centre of the roof). The whole Victorian original and later additions have been demolished to concentrate all services at 1 site. It closed in 2006 ie about 30 years. We live in a temporary society, what is in it's place? A Tesco supermarket, effectively a tin shed. Easy to build, easy to demolish and recycle. Insulation, air-conditioning, all ongoing costs.

[@jonathanstrange6227]

Lol I learnt so much about concrete builds and the different types when I bought a non standard build house… funny how slight differences between the build type makes so much difference

[@laslive693]

Wow ! Absolutely brilliant video !! I’m not in the trade, just a concerned parent and a health worker. Fantastic job and brilliantly presented. Thank you 😊

[@smokie01uk]

Not a builder or in the trade, just intrigued by the title to your video. Excellent work, you explained it better than every news article I've seen recently, well done sir 👏

[@SkillBuilder]

Glad you liked it!

[@Me-zo8yc]

House builders still manage to mess up standard designs by the thousands!

[@brianwebber2606]

Brilliant presentation Roger. Let’s hope someone in Westminster comes across your video.

[@over-engineered]

I think steel portal frame construction is probably the best solution for public buildings (galvanised preferably).

[@francesconicoletti2547]

The problem with steel is fire. While steel doesn’t melt at normal building fire temperatures it does soften. It looses its strength and the building sags , trapping people and causing more damage. The solution is of course to box the steel in with fire retardant material, like say some form of concrete. Now we get back to the rust as we have buried the steel inside another material and cannot inspect and maintain it. I think that’s one of the reasons people went to concrete in the first place, it was fire proof out of the box.

[@joshdaly2343]

​@@francesconicoletti2547generally in the UK, concrete frame buildings are used for hospitals and apartment blocks where there are likely to be people asleep and less able to quickly respond to fire alarms. Offices and department stores where people are generally only there in the day and can respond quicker to a fire are more likely to be made from steel framed structures as they are cheaper and the risk to life is lower.

[@over-engineered]

@@francesconicoletti2547 point taken re. steel and fire, galvanise it and box it in with fire rated plasterboard. Problem is governments don’t invest for the future and build for the long term, it’s all about cost now, not true cost over time.

[@travelbugse2829]

@@francesconicoletti2547 Sprinklers, surely?

[@AshGTE]

Great viseo. I live in Germany and one thing nobody talks about with RAAC is that at the end of its life it has to be disposed of as special waste (Land fill). This is very expensive in Germany. Normal building waste is rendered down and recycled. Not RAAC. Eventually it will become a huge problem to get rid of.

[@jonathanhenderson980]

Very interesting information and facts. Another bad thing about flat roofs is when they cover it with plant equipment and pebbles so there's little chance of finding the leak when there is one.

[@stephenfennell]

Thank you. That was nice and clear. I had to slow most of it down to 0.5 speed and 0.75 speed as you talk too fast for me to register and remember what you are saying, as I am not in the industry. But once slowed down it was great. I didn't quite follow the diagram where you showed a little right-angled triangle (representing shear?) at the end of the roof beam, but most of the rest was like a very good, clear lesson.

[@garethalbans]

Absolutely masterful explanation of the problem, and a valuable discussion point for looking at solutions. Should be shown to all MPs. I'm confident though that we will see many acrows in schools up to the end of the century!

[@simonjones7785]

great video no BS with a full and calm explanation of the product and its use in public buildings

[@mikerodent3164]

That was an excellent explanation and an excellent suggestion for the way forward. What a nightmare: the main fault here (apart from the flat roof idea in the first place, especially in rainy latitudes) was obviously having no thought about the lifetime of this material. Bubble it up, have a lab test it, and then bung it on thousands of roofs. Oh... may cause a nightmare in 60 years: yes, but by then humanity will be riding on jetpacks and all buildings will be made out of plastic... or something even better than plastic... and it'll take our robots in 2023 no more than five hours to build a new school.

[@lazaraza]

What a refreshing take on a depressing situation, thanks mate

[@4hisglory365]

Great video. My biggest concern for a few years is how this affects PREfab social housing. I requested exercising right to buy on a prefab and the document I received stating that the building materials were UNSAFE amazed me. Yea the houses are CHEAP to buy however £35K to bring them up to standard construction and receive a PRC certificate. Who’s responsibility is it to update these houses?? Surely not the tenants!!! Also are tenants being informed prior to signing a contract that whilst you can exercise right to buy and receive a discount, you’ll struggle to get a mortgage!!! What are your thoughts on this??

[@Mole-Skin]

Superb blog Roger.. I hope some Politician actually watch's and hopefully understands your solid information and advice.. As this RAAC issue becomes mainstream news, The 'Media' is doing their usual job of just looking for someone to blame and fogging up the issue.. As I understand it, Buildings (UK) are designed to have a minimum lifespan.. Residential is 60 years (I think..) So when the design is being considered by the Planners and BC this is what they accept.. But, also in the process is an accepted amount of maintenance.. especially for a flat roof.. Flat roofs are favoured by the Concrete Trade.. because they use lotsa concrete.. yay.. As Schools and Hospitals etc had their budgets slashed , maintenance was the first casualty and thus that 60 year use became 40 and we are now at that time.. So, as Roger says.. NO to flat roofs.. For Roofing look to Industrial Sheds for Insulated panels at shallow pitch.. which is a cheap and suitable option.. Leave concrete in the ground where it belongs.. Final point.. Track down the original Tech Drawings for the Building being inspected.. It should show what and where materials were used..

[@muttman325]

Just a superb piece. Works is so many ways. I will be linking this to builders,people i know in the media and politicians. Also teachers. That is how to teach.thankyou.

[@Michaeltroughton]

Well that was one of the most interesting and informative videos I've watched for a while. You clearly know your stuff.

[@markclinton9983]

I worked at a hospital last year and a contractor was “curing” it’s RAAC issues by passing an electric current through the re-bar and attaching a sacrificial bar to attract all the rust, seems like black magic to me

[@johnj.publicus1371]

It would if you didn't understand galvanic action...🙄

[@EdgyNumber1]

This is a fella that speaks absolute sense. Good video. 'Nuff said.

[@vincepeacham7292]

Great video and explanation, especially exposing the short sightedness of politicians 👏

[@ianlister6554]

‘Architects mincing about’! How very true.....

[@kevfquinn]

Thanks for the technical run-down - really useful to get a proper builder's description of what it's all about. Data as of 6th Sept identifies 147 affected schools (9 of the original 156 have been determined to have no RAAC), 43 of which are currently not full face-to-face teaching (delayed start, all-remote, or mixed face-to-face & remote). I see NAO reports 41 hospitals affected, 7 of which need a full rebuild - so far, development work has started at 1 (so much for Johnson's 40 new hospitals!) I wonder how many non-state buildings might be affected - housing blocks, offices, etc. Hopefully the management and insurance systems in place for commercial properties means things haven't being kicked down the road as much...

[@HomeRapidRepair]

Good information for sure 👍🏼👍🏼

[@yakacm]

The same thing happened in the 70's, I think it was quick drying cement back then. I remember my brother, having to do work at home in the run up to his final exams.

[@teacheme]

My old secondary school was built in the early 60's using mainly raac. 25 years ago serious issues of cracks in ceilings, walls and the roof were noted. The school approached the builders, who were still in business, and asked for the damage to be repaired under an existing long warranty agreement. The builders tried to get out of their obligations but, unfortunately for them, this was a Catholic school and the governors had the power of the church behind them. Long story short the builders were made to demolish the building and replace it with a brand new one using modern day materials and at no cost to the school. If only this could happen today.

[@clarky.]

Thank you for explaining this situation. Clear and precise.

[@andrewg9236]

Great explanation Roger,👏the cancellation of the school rebuilding program around 2010 under the austerity cut backs is coming back with a bite. In all sections of society as well...

[@Bluemoon4415-s5v]

I love it when he said just build the bloody things!

[@Joeink100]

we had marks on walls in one of the buildings in my school i remember asking what they where for and was told its so they know where the asbestos is and make sure not to nail or staple things into that wall, when i pointed out a load of stapled stuff she straight denied it until she got closer and said she's sure its fine

[@jessicamorgan3073]

Hi I came across your imformative video whilst browsing YT. I'm not in the profession, but a concerned member of the public. Did the people who commissioned/designed buildings with RAAC know about its limited lifespan? You make a good point about flat roofs. As you pointed out, they are an issue in the UK. All public buildings should have solar panels on them, especially in the SW of the UK, where there's the highest solar irradiance. Add in rain water collectors too! Whilst new, standard design, schools are being built, make sure there's space for playing fields too! I've seem a lot of construction sites where there regards already rusting, even before the concrete is poured over them. How is safe?

[@TheRaptorXX]

"Flat roofs are trouble", Spot ON!!

[@pulsartcreative4349]

I remember in the 60s , they had experimented with high alumina cement. A few years later, the stuff began to crumble. Hundreds of buildings had to be re-worked (Including the well known Catholic Cathedral in Liverpool. It seems like deja vu... Will we ever learn?

[@csehszlovakze]

thanks for the warning! I'll cross ytong off the list of possible building materials (leaning towards ICF)

[@cglees]

Good luck finding a surveyor who is confident to put their name on paper and sign something off as “safe”

[@AndymacUK]

Excellent video which everyone needs to see - well done.

[@therealcaldini]

As someone not involved in the building industry it’s the political commentary in this video that I enjoyed most!

[@marciabaldwin2506]

Fantastic video so eye opening as to the cause of the problem that's going on maybe the politicians should watch your videos my friend then it would be sorted out❤

[@LesSmeaton]

I'm a building control surveyor. There was a problem in earlier years was with HAC (High alumina cement). The aluminium was used to speed up the curing time. Then one day a HAC roof collapsed into a swimming pool and it was then banned from use thereafter. I believe the same problem exists with RAAC. It is very porous and if exposed to moisture over the years the reinforcement corrodes and detaches from the concrete. Once that happens there is not much left regarding support...

[@reedy8585]

You get what you vote for.

[@SkillBuilder]

And often you don't get what you vote for

[@reedy8585]

@@SkillBuilder yeah, lol

[@reedy8585]

@@SkillBuilder yeah, lol

[@stephenrenwick8781]

Great video sir, very informative...I am a teacher not a builder.i wa Ted to know if the issue was what I thought it was. Totally agree on the single design for schools. One design for primary and one for secondary. Additional classrooms are added to suit the local school population. New housing estate goes up, then simple to add Nother classroom.

[@alangilbert8627]

Surely the fix would be to fit a barer to the internal walls to take ceiling joists to support the ceiling from falling in. That would make the structure safe until the funds can be found to replace the building.

[@MatSmithLondon]

Final splurge of comments from me... ABSOLUTELY agree with the Pantheon bit at the end, what an inspiration. Not even reinforced! (Presumably why it has lasted so long - no failure due to exposed bar.) The only reason our concrete buildings fail all the time is that we ask them to do things that require the use of steel inside the concrete! (Bridges, flat roofs, etc...) I'm equally to blame as I've added to this problem (mind you - I have a high degree of confidence in our basement roof that it will last over a lifetime - the bar was installed to absolute perfection, and I personally read all the British standards and applied them to the build. There was only ONE company in the UK that actually provided the correct type of spacer for the particular design- I bet very few people actually use that spacer. Maybe they do in larger commercial builds...). That said, I still think a domed concrete roof without steel is preferable, maybe next time :)

[@SkillBuilder]

Hi Mat It has been a busy summer for me but I keep meaning to catch up with you and see where we are with your window problems.

[@MatSmithLondon]

@@SkillBuilder I have stuck my head in the sand re the problem, hoping it will go away - it hasn't - anyway I'm happily boarding up the rest of the place now. Would be good to catch up when you have a moment

[@sinisatrlin840]

I went to elementary school that was build by Austrian empire, my kids are now in their 7th and 8th grades in that same school. It survived few earthquakes and one avio bomb in WW2. And it has a flat roof with insulation and beige thick foil. (i think that foil gets replaced every 20 years or so). City has installed lift for hendicaped children on the outside and that is their biggest investment in 100 years besides painting walls, painting woodwork and changing some random door. Build once, build good.

[@arthur_scuba]

Thank You 👏🏼👏🏼👏🏼 Don't understand why people in the UK are still building flat roofs 🫣 Crazy!!!

[@503stick]

Thanks for the explanation, your a legend of the building industry 👏

[@grahamjesson5464]

wise words from a man who knows.! great vid.

[@thunderous-one]

Having a generic build or a standard design is a practical tried and tested formula. Look at the layout of your local supermarket like Waitrose and then go to another Waitrose branch, the layout is the same for familiarity. Thus no matter where you find yourself, you will know what is where in the branch you visit. I never understood why public building never adopted this model. Schools Hospitals Fire stations Police stations Libraries and so on.

[@michaelhicks3030]

Especially since this tale involves politicians and the government, i will definitely avoid the term "expert". Excellent and knowledgeable breakdown of the issues and more. I particularly liked the idea of achieving quality and cost effectiveness by standardized buildings. A suggestion, you should setup a think tank and spend the next the next 5 years at great expense, obviously, with the conclusion being this video. It would be infinitely more efficient than what will be done and quicker to boot.