Katherina Lewis, marketing manager of the Brick Development Association, talks about how cost and green issues are firing the demand for clay products.

THERE IS something very special about brick. It is probably the only building material, which, in certain lights, and with the right clay, firing and the right mortar, can be almost edible. That is partly because bricks are cooked in an oven in much the same way as, say, a Sunday roast. It is also to do with the fact that, like roast potatoes, bricks have a much closer visual connection with their raw constituents than anything else you’ll find in a modern building. That is especially true of old buildings because their bricks will have been pressed from the local clay and burned on or near the site in temporary tunnel kilns by families of bricklayers.

And like a great meal, great brickwork is designed, thought out and deliberated over. This can be to do with the mathematical accuracy of a wall of deep red engineering bricks with precise dark brown mortar. It can be heavy banding of different brick colours or subtly projecting stringcourses in a single band of different brick at each floor level. It can be a wonderful mixture of subtle tones and textures. And there are half a dozen different brick bonds and half a dozen different ways of striking mortar joints, which only people in the know understand but which can make an extraordinary difference to the way the layman perceives brickwork.

And because we have been building with brick for thousands of years, its technology is well understood, how to use it to keep a building dry, what kinds of bricks to use in different environments, how to cope with expansion and contraction, what physical and chemical effect different mortars can have on brickwork. And, recently, what happens when you glue bricks together in mortarless construction.

Cost comfort
At a time when prefabrication has become a fashionable notion, the misconception has developed that because bricklaying is generally an outdoor, onsite trade, it is expensive. The people who know about costs, the quantity surveyors, say that simply isn’t true. And their official body, the Royal Institute of Chartered Surveyors (RICS), took a look for the Brick Development Association (BDA) at bills of quantities from live projects submitted to them last year, along with the leading price books. They say that one square metre of brickwork laid in Suffolk cost just £44.57 and even in pricey central London was £58.92.

The sustainability game
Despite the universal use of the word “sustainability” these days, old construction
hands look at you sideways when it comes up in conversation. And well they might, because if you look at the current building material literature few manufacturers don’t make impressive ecological claims for their products. You can’t exactly blame them when there is some truth in the claims. And you can’t blame them when it is still quite difficult to get a handle on what sustainability really means and when there seems to be a number of paths to sustainability nirvana.

That’s not to say it shouldn’t be implemented and improved upon. The BDA, for example, in 2001 was one of the first construction industry bodies to issue its national sustainability strategy and set out key performance indicators to monitor the brick industry’s progress on reducing its emissions and improving energy efficiency amongst other criteria. Each BDA member has an environmental management system in place and 85% of the British brick output is certified to comply with ISO 14001. Meanwhile, the
MARSS figure for brick production, or the amount of material from alternative recycled and secondary sources, such as ash and hydrocarbons and organics, averages 12.08% and is reviewed year by year.

The BDA also reports its annual CO2 emissions to the EU Emissions Trading Scheme. Carbon emissions for brick are currently 28kg/m2. At the end of 100 years, for example, which is less than the useful lifespan of many current brick buildings, the embodied carbon from the firing of this abundant naturalmaterial has been expended, and the longer a brick building lasts the better the value.

Brick carbon miles
Until the early 19th Century, when canals and railways made it possible to transport building materials around the country, bricks were necessarily a local material. And that is still largely true in a time when facing stone is regularly sourced from China, slates from Brazil, timber from America, engineered timber from Austria, glass from France and cement from Greece. Low local prices encourage this. But now, as we are just beginning to understand the massive carbon cost of shipping, the carbon footprint of brick looks even more attractive.

Steel, aluminium and glass can be melted down and used again; some plastics can be heat and pressure-formed into sheets and special shapes. Brick, too, can be crushed and reused onsite and old lime mortar bricks can easily be cleaned up and used again as bricks. In the search to reduce carbon miles, it has become common good practice to process demolition material, including old brickwork, onsite and use it on the spot.

Whole life sustainability
Sustainability is not just about recycling or the use of carbon-free materials. Nor is it just about the embodied energy accrued through the processes of sourcing, production and transport. It is about the whole life energy consumption of a product. The crucial additional element in any sustainability calculation is how much it costs to look after a product once it has become part of a building.

It is here that brick people start looking satisfied, because the evidence is all around us that brick gets better and better as it gets older. And the cost in use of brick is virtually zero, as this highly durable material requires very little maintenance or repair. The effect of wind and snow and rain is not to deteriorate a building’s skin, as is the case with other materials. What weather does to brick is to mellow it.

There is also something very ecologically satisfying about bricks such as yellow London stocks and East Midland flettons. Their characteristic black flecks are an indication that ash has been included in the clay mix which, in the high temperatures of the kiln, ignites and helps to “cook” the bricks all the way through. Their not totally accurate name is self-firing bricks but the process has always made a contribution to diminishing their energy profile.

Lost skills?
There is another urban myth that most of the old brickwork skills have died out. Currently there is actually a surplus of trained bricklayers in the UK. An extension of the myth is that even if there is enough they don’t have the craft skills, which were needed in constructing the great flights of brick, fancy of the Victorian era. That’s not true either. The doomsayers who put this idea about seem to have forgotten first, that few people build Victorian architectural confections any more. But, second, when they do, there isn’t exactly a problem in finding the bricklaying skills.

Last year, as part of the rejuvenation and transformation of the old St Pancras railway station into the new international high-speed terminal, the architects designed a long, high section of brick wall on the western facade on Midland Road following exactly the old Victorian decorative pattern. It has been singled out as an exceptional example of brick craft. Yet on the other side of the road is the equally impressive brickwork of the British Library, sourced from the same clays as St Pancras, which, though it has none of the flourishes of the new work, has been executed with remarkable precision and clarity.

Modern classical architects, such as Quinlan and Francis Terry, have no hesitation in specifying traditional load-bearing brickwork because the skills are simply there and bricklayers respond to a challenge.

Lost ways return
We tend to think of the cavity wall as the inevitable way to do brickwork. Yet the cavity is a British custom, scarcely a hundred years old and not followed in many European countries. Many of us live in Victorian terrace houses with non-cavity solid nine-inch walls – which could do with additional insulation but, rarely, are in need of additional waterproofing. Oddly enough, the cavity wall is an early example of the rain screen wall, currently fashionable with commercial architects for non-brick walls, in which the
outer leaf controls the penetration of rain and drains it away before it can reach the insulated interior of a building.

Critics claim there are obstacles to returning to solid brick construction such as, unlike modern bricks, old bricks were very soft and the mortar was a sand-lime mix, which made the whole wall very forgiving.

However, the lime mortar’s function was to hold the bricks apart rather than to stick them together. Such a wall was permeable but, as those old terrace houses demonstrate, only infrequently did the water work its way across the full width of the brickwork. If the building insurance industry discourages that kind of thinking, the use of softer bricks and lime mortar is having a revival of interest.

Even quite short stretches of conventional brickwork need to have built-in expansion joints. With careful engineering design and soft lime mortar it is possible to build quite long stretches of brickwork without an inelegant break in their continuity.

And, reverting to an even earlier phase of brick history, one company is developing the use of unfired, or “green”, clay bricks as internal partitions washed with clay render. These have an embodied energy of one “spadepower”.

The latest development in rainwater management is Sustainable Drainage Systems using clay permeable pavements for driveways, paths and pedestrian plazas. Brick pavers with large spacer nibs are laid above a very deep bed of coarse aggregate, which serves as a slow draining underground water tank. The crushed stone jointing between individual pavers enables surface water to drain immediately into the sub-base for infiltration into the ground or a controlled drainage system.

---