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It is not often that a construction material comes to dominate the national media. But when it does, it is usually bad news rather than good. Asbestos, lead, high-alumina cement – they have all hit the headlines for the wrong reasons in the past.
Now it’s the turn of RAAC, which few had heard of until the start of the new school term, but about which most people now seem knowledgeable enough to express an opinion.
It seems that RAAC (Reinforced Autoclaved Aerated Concrete) was used in lots of schools and other public buildings from the 1950s to the 1990s, and that some of it might now be coming to the end of its useful life. The story was given added urgency by the fact that the Department for Education left it till a week before the start of the new school year to announce that hundreds of classrooms would have to close.
Like the other hazardous materials mentioned above, RAAC was once considered to be the next big thing. Lightweight, fast, and a good thermal insulator to boot – what’s not to like? Well, the fact that unless it’s properly maintained and kept dry, RAAC might only last for 30 years, that’s what.
Let’s just consider that last sentence, though – the bit about it being properly maintained and kept dry. Does that not apply equally to quite a few other building materials? Timber, for one, which has been used for millennia, but which only lasts for a few years if exposed to the elements of the British climate.
Same for paintwork, and brickwork, and most metals. All of these have acknowledged lifespans, and all of them have to be protected from the worst of the weather, and/or replaced as part of rolling maintenance programmes. What’s the life expectancy of a new flat roof? – if you tell most clients it’s guaranteed for thirty years, they’ll be more than happy.
I found out recently that when most of the UK’s millions of Victorian terraced houses were built, their life expectancy was 40 years. In an age when most people expected to live only into their fifties or sixties, that would not have seemed too bad.
The fact that so many of these Victorian houses are still standing, and providing sound and comfortable shelter, is a testament to the hard work of generations of builders, who have repaired, extended, re-plumbed, re-roofed, painted and decorated them for over 100 years.
I have also just read that when the iconic Tower Bridge, across the River Thames in London, was opened in 1894, it had a life expectancy of 99 years. That structure is not doing too badly, either. But it has had a fair bit of repair and maintenance along the way. Maybe that’s all that was needed to keep the RAAC schools in one piece.