The huge carbon cost of new brick means it’s time to turn to alternatives, such as stone, timber – or even recycled and reclaimed brick, says Anna Beckett
Wander down any street in London and there is one material that you’ll see more than any other: brick. The humble brick has been around in some form for thousands of years, and more traditional mud bricks are a fantastically low carbon building material. But fired clay bricks, the kind that we see everywhere in London (and much of the rest of the UK, for that matter), are pretty much the opposite.
Many of these historic buildings are incredibly attractive, and at the time that bricks were first developed, it made sense to use them. Following the Great Fire of London, timber framing was banned, and the London Building Act of 1667 dictated that new buildings should be constructed in masonry. Those historic brick buildings are a beautiful part of London’s heritage. The craftsmanship is often incredible, and the ornate details are just the kind of jazzy that I like.
But nestled in among these beautifully crafted buildings are some imposters – modern buildings which are clad in brick despite it making very little sense to do so. Buildings where the brick is supported from the edge of a concrete slab and structurally it’s a bit of a lie.
For a structural engineer, bricks are not a brilliant material. They work best in compression, carrying vertical loads down through the building, but the capacity is limited. If you apply a horizontal load, such as wind or a person leaning on it, then the capacity is even worse. Not really ideal for a wall. Bricks are also heavy, which is not what you want if you’re trying to support them from the edge of a third-floor slab.
So why do we continue to clad buildings in brick? The main reason seems to be to fit in with the buildings around us – to continue to create a similar aesthetic throughout our cities. But in the middle of a climate crisis does it really make sense to do that? And if it’s just about aesthetics, can we create the same appearance in a more sustainable way?
Stone has around two-thirds the embodied carbon of brick. It’s also heavy and not cheap, but it is still a lot stronger than traditional brick
Perhaps the easiest substitution would be to use stone. There’s already a precedent for building in stone, so it’s still in keeping with our cities, but stone has around two-thirds the embodied carbon of brick. It’s also heavy and not cheap, but it is still a lot stronger than traditional brick.
Or how about we limit the use of brick to those that are reclaimed? Every year we demolish thousands of buildings, many of which are brick, and yet we reuse only 5% of the bricks we remove. Yes, the buildings would need to be demolished more carefully and we would need to find ways to clean up the bricks to ensure that they weren’t damaged, but we could continue to build in brick without the carbon cost.
In recent years recycled bricks have also started to be investigated as a structural alternative. Herriot Watt University have developed the “K-Briq”, a brick that’s made from 90% construction and demolition waste. Products such as this may not yet be available on the market, but they have huge potential in terms of carbon savings while still looking and acting like a traditional brick.
Or maybe we accept that in 2022 we have materials that can do the job better than brick, and we cannot continue to create buildings that have such a huge carbon cost. We should go back to materials such as timber, which is lighter and more versatile and still creates a beautiful, if different, aesthetic.
What would the Victorians think of us?! We have all these new construction methods and materials that are much more efficient, yet we continue to build in brick just to mimic the buildings that they designed. Isn’t it time we started to create new cities for ourselves? Yes, keep the heritage, preserve the beautiful buildings we already have. But when we build something new, isn’t it time to prioritise our future over the past?