WHY BRICK IS BEAUTIFUL

Published for the BrickDevelopment Association

BRICKBulletin

SPRING 2007

Alan Short on the joy of form and feelingThermal mass matters: how brick answers the sustainability questionPlus: The Ark at Bukharra, UCL’s Slavonic School; Headlands House

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The Ark at Bukharra, UzbekistanBrick a World History by James W.P.Campbell and Will Pryce, published by Thames and Hudson £39.95

Photo Will Pryce © Thames & Hudson Ltd., London. From Brick: A World History by James W. P. Campbell, Thames & Hudson’

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The sumptuousness of the Ark at

Bukhara in Uzbekistan is atelling reminder that

brick has been around for a long time.Down the course of history the material hasresponded successfully to the many challenges posed by designers and builders.But recently the rate of change hasincreased dramatically and the challengeshave come thick and fast.

The manufacturing process has developed in response to environmentallegislation and is regularly out-performingthe targets for energy consumption andemissions set by the Government.

The demands of the marketplace havemeant that manufacturers have devised new products and processes not only toimprove site performance but also to ensure that there are techniques applicable to off-site construction.

Overarching this activity are the requirements of ‘sustainability’. A few yearsago this was a subject for the specialists –now it permeates every activity. The publication of a Code for SustainableHomes is a good moment to reflect on therelevance of brick to modern constructionand that is what this edition of the Bulletinseeks to do.

Michael Driver, director Brick Development Association

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A sumptuous reminder

Cover photograph: Steve Speller

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This low-energy house in southHertfordshire is a good example ofsustainable design. The building isdesigned to take advantage of the viewsfrom the site and to answer the client’s briefthat the fireplace be sited centrally as the

social and communal hub of the home.The skilled local workforce enabled the

architect to use brick to resolve complexforms not possible or cost prohibitive withother types of construction.

The colour and texture of the handmade

bricks and roof tiles blend well withsurrounding buildings.

The house has a high thermal mass,complemented by passive solar design anda ground source heat exchange system thatuses under-floor distribution.

Headlands House

The durability and longevity of abrick structure is welldemonstrated by this building, asis the use of thermal mass toprovide a stable environment inwhich to house a precious andvaluable collection.

Sandy Wright of Wright andWright describes how thebuilding has been ‘stitched intothe very fabric of the city toharmonise it with itssurroundings’. The cue is takenfrom the blackened brick façadeof the 1846 washhouse, nowreborn as the entrance to the

library. The durability of brick andease with which it can be alteredallows this structure to berecycled and ready to serve for atleast another 150 years.

The new build is finished inbrick externally and internally ascladding to a concrete core. Thethermal mass of this structurestabilises the temperature withinthe building and protects thearchive material. As a result thebuilding is naturally ventilatedwith energy consumption some80% less than that of an air-conditioned equivalent.

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Alan Short

While many architects still seek therevalidation of the super-lightweighttranslucent box – in the faint hope ofmiraculous new glasses which won’thaemorrhage energy – others are attemptinga recovery of authentic masonry architecture.The environmental benefits of thermallymassive construction are generally known,but I write here to commend the power andintensity of expression available through thepiling up of masonry units, the finest grainedof all being brick.

Perhaps there is, among a particulargeneration of architects, a fear of anunwelcome environmental determinismmanifested through banal, ‘passive solar’form-making in the hairy, grainy naturalmaterials of pre-history. However, with thebuilt environment contributing some 45% ofthe energy consumption of a Westerneconomy, I can confidently predict thatbuildings in the future will be different.

Current calculations of the potentialimpact of photovoltaics and other devices on

the requirement for 10% on-site renewableenergy generation are almost laughable. Thereal intent of this legislation is to provokedramatic order-of-magnitude reductions inenergy demand through judicious design.The legislators don’t have much of an idea ofwhat this new architecture is going to be like.That is up to us. The incorporation of brickmasonry construction as a fundamentaldriver is certainly an interesting startingposition to adopt.

Should ambitious architects be afraid? No.If one rejects the long discredited idea of anarchitectural ‘progress’, the predeterminedrevelation of better ideas invalidating theirpredecessors, and substitutes an iterativecontinuum of experimentation andrefinement within the greater continuum ofhuman culture, a reservoir of designstrategies becomes available. Brick masonrycan be vastly more meaningful than therolling out of civic-scaled planes ofunrelieved stretcher bond.

Unwisely perhaps, we have spent many

hours over the last two decades unravellingWilliam Butterfield’s syncopated jazzbonding patterns, most particularly at Kebleand All Saints, Margaret Street. Now wewholly understand why one would embrace,with vigour, constructional polychromy tocommunicate this animation of the actualphysical stuff of the building. Emotionalintensity of this order is not generated byenamelled steel panels.

Calcium silicate brick is peculiarlyexpressive in this type of work; one could,until recently, evoke the beautiful, andanything but ‘unadorned’, interiors ofHendrik Petrus Berlage’s Amsterdam Beurs,in cinammons, buffs, gingers, dead whites,silver greys and even pale greens. What ascandal that the lazy disclaimers word-processed into insurers’ documentation haveall but killed this industry.

Here is a fundamentally communicativearchitecture, ingeniously interconnectingstrings of simple rectangular prisms,themselves constructed from very smallrectangular prisms, seen at a dazzlingly highlevel of resolution in the apparently casualbut subtly disciplined house forms of Shawand his contemporaries.

But above all, despite our bestendeavours, we marvel at Frank Furness’swildly, violently expressive library at theUniversity of Pennsylvania, a completelyoriginal conception crashed together fromindistinct, inky illustrations in ‘The Builder’and other long out-of-date Europeanpublications; he wasn’t much of a traveller,thank goodness, or he wouldn’t haveachieved his shocking new synthesis.

Here the bricks become the red hotmolten medium for the transmission ofFurness’s extraordinarily original andperiodically evil spirit; he sworecontinuously. In his library, for which thedrawn elevations are barely believable intheir deliberate chaos, red sandstone is usedto clamp the expressive pressures developingin the sizzling brick panels.

In the end the lone designer sitsconfronting a blank sheet, anxious to inventsome kind of architectural prose, even poetry,and no amount of scholarly contextualisingis going to help. Why is the idea of brickmasonry such a potent companion in thislonely task? Why does it invoke such‘empathy’, or ‘Einfuhlung’, the humanresponse Worringer, another practicefavourite, proposed to explain the directconnection between form and feeling inarchitecture.

Perhaps he was less original than wethought, as Jarzombek has revealed, butnonetheless ‘empathy’ as a concept mightjust help in the invention of this new anddesperately needed sustainable and humanearchitecture, an architecture which mightturn out to be more familiar than might beexpected.

Buildings in the future will be different, and ‘empathy’ as a conceptmight just help in the invention of a new and desperately neededsustainable and humane architecture

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Sustainability is a current buzz word that hastransformed attitudes in the constructionindustry. Those who would once only pay lipservice to the concept are now seriouslyexamining their products and processes toidentify, evaluate and improve theirsustainability credentials.

The brick industry was one of the foundermembers of the Government’s PioneersGroup and it was one of the first UKindustrial sectors to publish its sustainabilitypolicy. This was based on a Governmentstrategy designed to be applicable to allindustrial sectors, holistic rather than simplybeing concerned with energy consumptionin manufacture and construction. Itsunderlying principle is that sustainability isabout the responsible use of resources.Alternatively, seen from the BrundtlandCommission’s angle, it concerns ‘meeting theneeds of the present without compromisingthe ability of future generations to meet theirown needs’.

Underlying these two definitions are fourkey points that lie at the heart of theGovernment’s thinking on sustainability:1 Social progress that recognises the needs

of everyone2 Effective protection of the environment3 Prudent use of resources4 Maintenance of high and stable levels of

economic growth and employmentHaving identified the areas of possible

improvement the brick industry took its firststeps in what has become a dynamic andongoing process. A set of key performanceindicators (KPIs) were selected to allow theindustry to predict, measure and review useof resources and chart progress towardsdefined aims. These KPIs are evaluated andreviewed annually.

Social progressThe brick industry’s objectives includeimproving the occupational health andsafety of its employees, introducing relevant,useful vocational training to improveemployee development, and maintainingand further developing liaison with, andsupport for, local communities. This latterpoint is particularly important as manybrickworks are located in rural areas.

Protection of the environmentThe clay brick industry is working hard tominimise the visual and environmental

Sustainability in thebrick industry

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impact of clay extraction sites. Exhaustedpits are being restored to beneficialcommunity use, incorporating treeplanting, imaginative landscaping, and thecreation of lakes for leisure or natureconservation programmes. As part of itsenergy commitment, industry will reduceenergy consumption by more than 10% by2010 under the Government’s climatechange levy. Progress reports indicate thistarget is likely to be exceeded.

Prudent use of resourcesBDA members recognise the importance ofmeasuring and reducing the consumptionof natural resources such as the volume oftreated water and energy use. It isimportant that the resources consumed inproduction are evaluated over the wholelifecycle of the product. It is pointless

highlighting the consumption of aparticular resource without taking intoaccount the fact that brick has been shownto last hundreds and sometimes eventhousands of years.

Economic growth and employmentThe industry employs 5,500 people overnearly 90 manufacturing sites. Maintaininghigh and stable levels of economic growthand employment is therefore crucial. Thiswill be achieved by maintaining andimproving profitability to provide forcontinuing investment and employment;increasing investment in plant andmachinery in order to improvemanufacturing efficiency andenvironmental performance; anddeveloping new products to increase added value.

Objective Reducing the impact of atmospheric emissions from the production process

KPI: CO2 emission per square metre of brickwork

Tonnes CO2 / sq metre / annum2000 0.0002352005 0.000232

The measure reflects the contribution of CO2 emissions per square metre of brickwork per annumattributable to brick assuming an average expected service life of 120 years. The CO2 emissions com-prise direct emissions from energy and process as reported under the EU Emissions Trading Scheme.

Objective Reducing energy consumed through improved energy efficiency

KPI: Specific energy consumption per tonne of output

Output (tonnes) Energy consumed (KWh) SEC2001 6,539,688 51,000,130,531 779.92005 6,357,704 4,810,757,299 756.7

Energy comprises a major cost for the industry. Consequently there is ongoing commitment toimproving efficiency. In addition the industry has participated in Climate Change Agreements since2001 and is subject to the EU Emissions Trading Scheme.

Objective Minimising virgin raw material (clay) consumption

KPI: Proportion of raw materials derived from sources other than clay extraction

Research undertaken recently by CERAM Building Technology has established that:8.3% of the industry's raw materials are derived from sources other than the primary extractionof clayThis equates to 643,000 tonnes of materialsThe industry has very close to 100% internally generated process waste recovery and recycling

It is intended that this measure will be continued in future years.

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School of Slavonic studies

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Short & Associates

The building created to house the School ofSlavonic Studies at University College,London, is the latest of Short Associatesdesigns to use natural ventilation for a largebuilding. It is the first time that passivedown-draft cooling has been used on apublic building in a major city.

The thermal mass of the masonry of themain elevation and the staircase zone behindit allows the stair void to act as a hugeventilated cavity. This tempers the building’sinternal temperatures working inconjunction with the central glass atrium that rises through the middle of the building,

the perimeter stacks and roof-mountedchimneys.

The brickwork of the façade consists of anouter 215mm-thick solid brick wall tiedacross a 100mm cavity to an inner 215mmwall that is left fair-faced. The dentilledarchitrave to the main elevation doubles asan ingenious exhaust duct.

The confident detailing of the brickworkshows how, with care and thought, it ispossible to use brick to produce anarchitecture that is vibrant and dynamicwhile at the same time creating a buildingwith impeccable sustainability credentials.

Three principles guided the design ofthis building for the National Trust. Thebuilding had to be:1 The most sustainable building

possible within budget2 The best possible working

environment3 The most appropriate contextual

response

The trapezoidal plan is capped bysaw-tooth roof lights that are used forboth north light and foraccommodating south-facingphotovoltaic panels. The roof createsthree gabled elevations that are built inStaffordshire Blue brick. The externalwalls are 442mm thick with a U-value of0.2 achieved by a 140mm-thick internalconcrete blockwork (renderedinternally to capitalise on thermalmass), a 200mm cavity containing150mm of high-performance insulationand the 102mm-thick external facingbrickwork laid in lime mortar.

Internally, the exposed thermal massin the walls and fair-faced concretesoffits help to mitigate solar gainsassisted by natural ventilation and nightcooling in summer. The distinctive roofcowls promote both stack and wind-driven ventilation.

The building achieved an ‘excellent’BREEAM rating. It provides first-classworking conditions and sits comfortablyin the context of the Victorian railwaysheds of Brunel’s Great WesternRailway.

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The current debate on construction hasdeveloped into an argument about therelative merits of different materials andwhether specific methods of construction aremore sustainable than others.

This debate misses the point; namely thatit is the prime responsibility of everyone inthe construction industry to create spacesand places that enhance people’s lives. Unlesswe build houses that are good to live in andin communities that function well, we willcreate a tranche of buildings that peopledon’t respect and therefore seek to destroy.You have only to revisit the housing boom ofthe 1960’s to see what happens wheninhabitants are alienated.If enhancing people’s lives is the primaryfocus it still must be achieved sustainably,that is through a responsible use of resources– be they human, physical, or financial. It isthese considerations that reinforce the casefor brick because in brick we have a materialthat is:

Aesthetically pleasing and mellows withage, people feel comfortable living with itDurable and long-lasting, requiringminimal maintenanceWell understood yet capable of furtherdevelopmentAble to be used in conjunction with othermaterials and all construction systemsEasy to adapt to accommodate the changesin the function of the buildingFireproof, insect and water resistantSustainable because it is created as a resultof a responsible attitude to human, naturaland physical resourcesGood value whether you are consideringinitial cost or lifecycle cost

Embodied energyBrick production at its most fundamental is acombination of earth, water and fire. Clay isdug, moistened and formed, then dried andfired. However, modern production is asophisticated version of the fundamentalprocess. Clay is usually dug near the factory,prepared on site then formed by throwing,pressing or extrusion before being dried inchambers warmed by heat extracted from thekilns. Waste clay is recovered and returned tothe process. Fuel-efficient kilns, generallyfired by gas but also by methane recovered

Brick and brickwork:production and use

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from landfill, or other alternative sources,have reduced the energy consumed whilstdevelopments in flue technology havereduced the emissions. The brickcomponent in a square metre of brickworkproduces 27kg CO2 by the time it isdelivered to site. This equates to 0.000232tonnes/per sq metre/per annum over a lifespan of a 120 years. To put this into contextrecent studies suggest that at 60 years theratio of embodied energy of construction tothe operational energy in a building is 1:10.

Installed cost of brickworkThe construction techniques that involvebrick are well understood. What is lessappreciated is the value of the installed costof brickwork. The current price for a squaremetre laid of facing brickwork is around£35. The brick component in this equationis around £15 to £18 per square metre.

Lifespan of clay brickwork wallingIn the Green Guide to Specification,(Howard et al 1998) it states: ‘Brickconstruction may indeed last manyhundreds of years.’ While in the PhD thesisWhole Life Performance of Clay MasonryBrickwork written by Adrian Brown ofLeeds Metropolitan University there is arecord of a survey of 860 domestic and low-rise brick built properties across the Northof England. Twenty two per cent of theproperties are more than 140 years old, 12%

are between 100 and 140 years old, 8% arebetween 80 and 100 years old, 32% arebetween 60 and 80 years old and 40% areless than 60 years old.

The object of the survey was todetermine how much maintenance, repair,and renewal has been carried out on thebuildings and to draw conclusions on thelife expectancy of the structures. The oldeststructures were solid wall construction withcavity wall introduced in the last 100 years.The conclusions are that, given sensiblemaintenance and repair, there is no reasonwhy brick structures shouldn’t beconsidered to have a life of 500 years andbeyond. Repointing first occurs on averageafter 85 years and by then some of thebuildings had experienced some repair –for example to lintels or the replacement ofa few bricks. The message is that ifbrickwork is well built and maintained itwill continue to do its job efficiently andeffectively for a long time.

RecyclingThere are many reasons why buildings aredemolished. However, it is unlikely to bethat the brickwork is in such poor conditionthat it is not worth keeping. Brick buildingsare often recycled, fulfilling functionsdifferent to those for which they weredesigned. Their basic construction makesthis a good option and it is certainlysustainable.

However, if there is no option other thanto demolish it is still possible to benefitfrom a brick building. There is a thrivingmarket in reclaimed bricks and while aspecifier needs to be careful to check thequality of the reclaims there are manyexamples where the new build hasbeen successful.

Modern bricks have carefully definedproperties. In future this will take the guesswork out of the use of reclaimed bricks and,along with the use of mortars that can becleaned off the brick, will maintain thepopularity of the material.

If reclaiming the brick is not an optionthere are many uses for crushed brick.Shale tennis courts, green roofs, paths andgeneral construction hardcore means thatthere will be very little disposed to landfill.

The constructiontechniques thatinvolve brick arewell understood.What is lessappreciated is thevalue of theinstalled cost ofbrickwork

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The chronicles of MARSS: alternative,recycled and secondary resources

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Survey

One measure of sustainability is the amountof material from alternative, recycled andsecondary sources (MARSS) that is includedin a product. In the case of clay bricks, thesematerials replace the primary clay therebyconserving existing stocks.

In 2006 CERAM was commissioned bythe industry to carry out a survey of the useof MARSS in brickmaking.

The survey covered 51 factories usingMARSS materials representing 67% of theproduction sites in the UK and

accounting for more than 85% of the clay used in the manufacture ofclay bricks.

The survey identified 28 differentMARSS materials divided into six majorgroups – their use is recorded above.

Manufacturers were asked to identify thebenefits and reasons for the use of MARSSmaterials. Non-primary clay (generally fire-clay) accounted for nearly 44% of MARSSmaterial usage, bulking additives 15% andcolourants 9%.

The pumping station atPapplewick is a rare example ofa group of buildings that areboth listed and a scheduledancient monument. Erectedbetween 1882 and 1885 by OgleTarbotton for NottinghamCorporation Water Department,the complex is a fusion ofarchitecture, engineering, art and landscape. Papplewick wason the English Heritage list ofBuildings at Risk, but thePapplewick Trustees andAssociation obtained a BIFFAaward to carry out repairs led byCullen Carter Hill.

A structural assessment of thebuildings showed that after 120years the structural componentsof the building were in good

condition but repair andrestoration was needed to thegeneral fabric.

The brickwork and terracottaplasters and mouldings weresatisfactory and it was onlywhere the face of a brick wasblown that new brickworkwas required.

Bricks were specially made tomatch the original, together withmouldings for the pumpingstation, boiler house, chimney,and superintendent’s house.This fine group of buildings willbecome a valuable resource forboth the public and scholars.They are ample evidence of thedurability and longevity of brickstructures – key componentswhen considering sustainability.

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Cullen Carter Hill

Recovered water accounts for 33% of all the water used in the brickmakingprocess.

This is an important contribution tosustainability because recovery saves theuse of treated water. It should go withoutsaying that the industry is determined toimprove this figure year on year.

While individual factories make more orless use of MARSS materials, the averagepercentage addition rate in a brick is 11.89%.

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Pallant House Gallery: Chichester

Long and Kentish in association with Colin St John Wilson and Associates

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Pallant House, originally built in the 17thcentury for a Chichester Merchant now hasanother life as the home for the PallantHouse Collection of early twentieth century

art. The house was renovated and extendedthrough 2004-6 by architcet Long andKentish to accept the collection of ColinSt John Wilson.

It’s stands as a clear demonstration of theadaptability of brick structures and howskilful use of the material gives a commonthread to the house and its extension.

Engineer James Cubitt (1811-1872)and Contractor Thomas Brassey(1805-1870) were responsible forthe wonderful Digswell Viaductwhich carried the twin tracks of theGreat Northern Railway across theMimram Valley.

The viaduct is a whopping 470mlong. The 40 arches each span 9.1mand are up to 30m high.Thirteenmillion bricks were used in itsconstruction.

This structure is still carryingthe East Cost Main-line and othertraffic and is a prime example of thedurability and longevity of brick.

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St Pancras challenge

When St Pancras was built in the early 1870sit was the largest rubbed and gaugedbrickwork project in the world, consumingvast quantities of facing bricks and all of theUK stock of washed rubbing blocks. Whenthe west elevation was to be rebuilt as part ofthe works for the Channel Tunnel Terminusthere were people who said the Britishconstruction industry no longer had thenecessary craft skills to handle difficult large-scale projects with intricate brickworkdetailing.

However, the brick industry, in the shapeof Charnwood Forest Brick and Bulmer Brick& Tile, showed the materials could be

manufactured. Bulmer Brick Cutting provedequal to the task of cutting and supplying22,000 pieces and Irvine Whitlock’sbricklayers demonstrated that their skilllevels were at least the equal of theirVictorian counterparts. When the Victorianfacing bricks from St Pancras were analysed itwas clear that the clay had come fromLeicestershire. However, the shape of thebrick and the finish to the face required areappraisal of current hand-throwingtechniques. Instead of the face being theresult of clay meeting the mould, the face ofthe St Pancras brick was the open side of themould, meaning that the bricks were thrown

sideways. This gave a frog on both sides. The moulds were deeper than normal and

turning out the clay was difficult because ofthe mould shape and the position of thefinished face. Brickmakers at Charnwoodproved equal to the challenge andmaintained a steady supply of facing bricksin accordance with the constructionprogramme.

Bulmer Brick was successful in quotingfor the red rubbers in conjunction withBulmer Brick Cutting. While manufacturingred rubbers is well understood, theproduction of a large quantity of cut bricks tovery fine tolerances needed some lateralthinking. Bricks are cut to templates and,rather than employ conventional patternmakers, Bulmer approached a laser cuttingcompany that normally works in thepackaging industry to laser cut 15mm birchply templates from CAD drawings.

In order to achieve cuts that tapered0.5mm over 115mm and 1mm over 229mm,Bulmer redesigned the standard masonrycutting saw bench so that it was able tomaintain accuracy over an extended period.

Finally, the shaped pieces had to bedelivered to site to allow the arches to beconstructed with confidence. This wasachieved by devising a system of purpose-made packing trays containing bricks packedin the correct sequence for laying.

The bricklayers of Irvine Whitlockrelished the opportunity to demonstratetheir skill laying the facing bricks in a limemortar of 5mm thickness and the rubbedbricks and stone in fine 2mm joints using apure, sand-free lime putty. The evidence oftheir skill will be on view for many years.

The significance of this project is that eachcomponent of the supply chain showed theability to solve problems and then deliver. Itshould inspire other designers to design inbrick confident that the industry is able torespond to any challenge.

There is a perception that thereis a shortage of bricklayers inthe UK and this is always citedas a reason for using alternativemethods of construction. How-ever, this perception is wrong.Speak to Geoff Irvine, Chairmanof brickwork contractors Irvine

Whitlock and Chairman of theAssociation of Brickwork Con-tractors, and he will tell youthere is no shortage of skilledtradesmen.

The problem might be thatsome contractors do not valuethe services of bricklayers,

hence they will find it hard torecruit. But if the tradesmen aretreated fairly, Geoff will tell youthat there is no evidence of ashortage.

A simple calculation supportsGeoff's assertion. The CITB gives117,500 as the number of brick-

layers in the UK. If each brick-layer lays 500 bricks per day for5 days per week the output ofthe UK brick industry will be laidwithin 10 weeks. This leavesplenty of time for bricklayers tolay blocks and do all the otherthings they do.

Bricklayer Shortage

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01 Angle brickA neat way of producing any angle in a runof brickwork.

02 Spiral brickA single brick that produces a spiral barleytwist column.

03 Tile brickAn extruded clay unit that replicates tilehanging. Laid by bricklayers, it allows ‘tile-hanging’ to be incorporated into a façadewithout a change of trades.

04 Different formatsA series of large format clay blockscomplement the different sizes thatmanufacturers now offer.

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05 Pre-assembled brickworkPre-assembled feature brickwork detailsfor incorporation into standard masonry.Illustrated are bulls-eye and stack bond.Also available basket-weave, quoins,dentils, bonding course and solider coursepolychromatic brickwork.

06 Prefabricated brickworkOff-site assembly of completecomponents, such as columns at theInland Revenue Building, Nottingham, andbrickwork at The Grove, Watford.

Brick manufacturers are awarethat they have to expand theirproduct line beyond the traditionalbrick. This has resulted in anumber of new products that canbe grouped under three headings:The Unit, The Component and The Process.

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07 CoriumA system that provides a mechanical fixingfor a clay tile to a plastisol-coated metaltray. A variety of tile shapes is available.

08 Thin joint brickworkA modified sand and cement mortar thatglues brickwork together. The mortar ismixed and pumped through a hand-heldnozzle. The joints are 3mm-4mm andthere is no mortar in evidence, hence theeffect of the clay is intense. Applicable forboth on-site and prefabricated brickwork.

09 WonderwallA system that glues brick slips on to aninsulated backing sheet.

10 Traditional PlusA single brick external wall using a140mm-wide brick. Intermediate floorsand restraint ties are located in the brick.The insulation is placed on the internalface of the external wall.

11 Earth bricks A range of unfired clay bricks and blocksintended for internal use. Excellentsustainability credentials, low energyinput, low waste, fully recyclable. They givea building thermal mass, inhibitcondensation and regulate the relativehumidity of the atmosphere.

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Why masonry mass could be critical

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There is now an overwhelming body ofevidence, documented in the recent SternReview, for climate change caused bygreenhouse gases. And The Met Office datacontinues to forecast a warmer climatethrough the latter part of the century.

As a result it is quite likely that homes ofthe future could require mechanical coolingin order to maintain a comfortableenvironment. However, the impact of releaseof the resulting CO2 into the atmosphere(together with concerns over the security ofthe energy supplies) have given rise to adifferent appraisal of performance ofbuilding components and fabrics.

Overheating may be avoided by:Improved ventilation through suitableventilation stacks, ducting and naturalconvectionSolar shading through correct orientationof building, blinds and shuttersActive use of thermal mass

The mechanism by which 'heavyweight'building structures absorb and release heatin a way which is beneficial to the occupantsis shown in figure1 below. As the outsidetemperature rises heat is absorbed bythermal mass during the day and then slowlyreleased during the night.

Heavyweight masonry buildings:Absorb heat during daytimeRelease heat during night timeThe 'lag' illustrated helps to stabilizeindoor temperaturesIn contrast insulated lightweight

structures tend to absorb and dissipate heatmuch more quickly.

Historical precedencePassive Solar Design or PSD utilizes anefficient combination of thermal mass,natural ventilation and solar shading and hasbeen successfully used in the Middle East forcenturies. The sketch, top left, shows theprinciples of how wind is used as the sourceof clean and natural ventilation in a dwelling.A tower 'catches' the wind and directs it tothe interior of the building; shades andshutters are used to moderate the effects ofoutside temperature on the indoorenvironment and complement thesustainable architecture of a claymasonry building.

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Figure 1: Illustration of thermal mass benefit of ‘heavyweight’ structures

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Brick has been a reliable constructionmaterial for centuries – and with goodreason.

It is user friendly, relatively easy tomanufacture and offers unparalleledversatility in use.It is compatible with many different formsof construction.It offers a durable attractive envelope withproven performance.It makes a significant contribution as astructural component.It has excellent flood resistance/resilienceproperties; a CIRIA report (to bepublished) places Engineering Bricks atthe top of its recommended materials ofconstruction for dwellings.

It is this latter point that is leastunderstood and is highlighted here.Brickwork, made with standard UK bricks,can accommodate movement better thanother forms of masonry:

The larger number of joints offers a more‘articulated’ form and reduces strainconcentration.Spacing of movement joints in claymasonry is about twice that in cementitousmasonry.

Brickwork contributes to strength andenhances structural performance. In a‘standard’ cavity wall construction of 100mminner leaf blockwork and 102.5mm outer leafbrickwork and a typical storey height of 2.5momitting the brickwork has the followingconsequences:

A minimum of 135mm-thick blockwork isneeded to achieve the same verticalloadbearing capacity.For the same thickness blockwork the wallis some 37% weaker.A single leaf wall requires insulation andrender or some form of rainscreen – bothof which increase the overall thicknesswithout any structural benefits.

In a typical brick and block cavity wallpanel, 2.5m high x 5m long in simplebending along the bed-joints:

150mm thick blockwork is needed tocompensate for omitting brickwork, againwith render/rainscreen and insulation.And in case of orthogonal bending of the

panel:Some 70% of the bending strength isprovided by the brickwork with furtherenhancement if the self-weight is takeninto account.Lower orthogonal ratio of brickworkresults in a greater two-way action of thepanel.The enhancement by the brickwork to

laterally loaded masonry panels applies toload-bearing masonry as well as masonryinfill walls to frame structures.

It is therefore clear that brickwork is notjust a pretty face and when used as so-calledcladding it makes a significant structuralcontribution.

The structural role of brickDr Ali Arasteh

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Figure 1: Vertical loading only

Figure 2: Lateral loading only

102.5

Tied cavity wall Single leaf Single leafBoth require rainscreen cladding + insulation

Tied cavity wall Single leaf Single leafBoth require rainscreen cladding + insulation

100 135 100

102.5 100 150 100

= OR But 37% weaker

= OR But 70% weaker

Brickwork

Insulation

Blockwork

Brickwork, 7<mc<12

Insulation

Blockwork, 3,6 N/mm2

Masonry in mortarstrength class M4/M6

Baggeridge Brick plcFir Street, Sedgley, DudleyWest Midlands DY3 4AATel: 01902 880 555Fax: 01902 880 432email. enquiries@baggeridge.co.ukwww.baggeridge.co.uk.Sales office: T 01902 880 666F 01902 880 432E sales@baggeridge.co.ukLondon consultancy:T 020 7236 6222F 020 7248 6363Rudgwick sales office:T 01403 822 212F 01403 823 357

Blockleys Brick LtdSommerfeld RoadTrench LockTelford, Shropshire TF1 4RYT 01952 251 933F 01952 265 377E sales@blockleys.comW www.michelmersh.com

Bovingdon Brickworks LtdPudds Cross, Bovingdon, Near HemelHempstead, Hertfordshire HP3 0NWT 01442 833 176F 01442 834 539E info@bovingdonbricks.co.uk W www.bovingdonbricks.co.uk

Broadmoor Brickworks LtdWhimsey, CinderfordGloucester GL14 3JAT 01594 822255F 01594 826782E sales@broadmoor-brickworks.co.uk

Bulmer Brick & Tile Co LtdBrickfieldsBulmer, SudburySuffolk CO10 7EFT 01787 269 232F 01787 269 040E bbt@bulmerbrickandtile.co.uk

Caradale Traditional Brick LtdEtna WorksLower Bathville, ArmadaleWest LothianEH48 2LZT 01501 730 671F 01501 732 991E Carolyn@caradle.co.ukW www.caradale.co.uk

Carlton BrickGrimethorpe, Near BarnsleySouth Yorkshire S72 7BGT 01226 711 521F 01226 780 417Sales Line: 01226 715 000

Charnwood Forest Brick LtdOld Station Close, Shepshed Nr LoughboroughLeicestershire LE12 9NJT 01509 503 203F 01509 507 566E sales@charnwoodforest.comW www.michelmersh.com

Coleford Brick & TileThe Royal Forest of DeanBrickworks Cinderford,Gloucestershire GL14 3JJT 01594 822 160F 01594 826 655E sales@colefordbrick.co.ukW www.colefordbrick.co.uk

Dunton BrothersMeadhams Farm BrickworksBlackwell Hall LaneLey Hill, CheshamBucks HP5 1TNT 01494 772 111F 01494 791 255E sales@duntons.comW www.michelmersh.com

Errol BrickInchoonans RoadErrol, Perth PH2 7RBT 01821 642 653F 01821 642 427E info@errolbrick.co.uk

Freshfield Lane Brickworks LimitedDanehill, Haywards Heath Sussex RH17 7HHT 01825 790 350F 01825 790 779E sales@flb.uk.com www.flb.uk.com

Hammill Brick LimitedWoodnesboroughSandwichKent CT13 OEJ T 01304 617 613F 01304 611 036

Hanson Building ProductsStewartby, Bedford MK43 9LZLondon, Butterley, Desimpel,Red Bank, Wilnecote Range. T 0870 609 7092F 01234 762 040E info@hansonbp.comW www.hansonbrick.com

H G MatthewsThe BrickworksBellingdon, CheshamBucks HP5 2URT 01494 758 212F 01494 758 077

Ibstock Brick LtdIbstock, Leicestershire, LE67 6HST 01530 261 999F 01530 257 457www.ibstock.co.ukScotland:Glasgow T: 0870 903 4001North West:Parkhouse T: 0870 903 4007North East:Throckley T: 0870 903 4004 Eastern:Leicester T: 0870 903 4008West Midlands:Lodge Lane T: 0870 903 4006South West:Cattybrook T: 0870 903 4010South East:Laybrook T: 0870 903 4012

Kingscourt BrickKingscourt,Drumsgill County Cavan, IrelandT +353 (0)42 9667 317F +353 (0)42 9667 206E info@kingscourtbricks.ieW www.laganbrick.com

Michelmersh Brick & Tile Co LtdHillview RoadMichelmersh, Romsey SO51 0NNT 01794 368 506F 01794 368 845E sales@michelmersh.co.ukW www.michelmersh.com

Normanton Brick Co Ltd Altofts Brickworks,Greenfield Road, Normanton West Yorkshire WF6 2DJT 01924 892 142 / 01924 895 863F 01924 223 455

Northcot Brick LimitedBlockley, Near Moreton-in-Marsh,Gloucestershire GL56 9LHT 01386 700 551F 01386 700 852E info@northcotbrick.co.ukW www.northcotbrick.co.uk

Ormonde Brick LtdCastlecomber County Kilkenny, IrelandT +353 (0)56 44 41323F +353 (0)56 44 41314E ormondeb@iol.ieW www.ormondebrick.ie

Phoenix Brick Company LtdThe Brickworks, Campbell Drive Barrow Hill, Chesterfield S43 2PRT 01246 233 223F 01246 230 777E enquries@bricksfromphoenix.co.ukW www.bricksfromphoenix.co.uk

Wm. C Reade of Aldeburgh LtdAldeburgh Brickworks 70-72 High Street, AldeburghSuffolk IP15 5AFT 01728 452 982F 01728 454 957E reception@msoakesltd.co.uk

Swarland Brick Co LtdThruntonWhittinghamAlnwickNorthumberland NE66 4SDT 01665 574 229F 01665 574 400E chris@swarlandbrick.fsnet.co.uk

Tyrone Brick Ltd48 Coalisland Road, DungannonNorthern IrelandBT71 6LAT 02887 723 421F 02887 727 193W www.tyrone-brick.com

The York Handmade Brick Co LtdForest Lane, Alne, York YO61 1TUT 01347 838 881F 01347 838 885 E sales@yorkhandmade.co.ukW www.yorkhandmade.co.uk

W H CollierChurch Lane, Marks Tey,Colchester, Essex CO6 1LNT 01206 210 301F 01206 212 540E sales@whcollier.co.uk

Wienerberger LtdWienerberger House, Brooks Drive,Cheadle Royal Business ParkCheadle, Cheshire SK8 3SAT 0161 491 8200F 0161 491 1270E office@wienerberger.co.ukW www.wienerberger.co.uk

The Brick Development Association Ltd.Woodside House, Winkfield Windsor, Berkshire SL4 2DXT 01344 885 651F 01344 890 129E brick@brick.org.ukW www.brick.org.uk

BDA: promoting the best of brickMichael Driver

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The Brick Development Association (BDA)was established to promote the best possibleuses of clay brickwork and clay paving. Thisincludes maintaining and disseminating thetraditions that have made brick one of thegreat materials of construction. But it alsoincludes supporting ongoing research intonew uses for brickwork that will ensure itsuse well into the third millennium. Helpingthe BDA achieve these goals are its memberswho together account for over 98% of claybrick manufacture in the UK and Ireland.

A wide range of BDA activities are

designed to promote excellence in thearchitectural, structural and landscapeapplications of brickwork. These arespearheaded by the Brick Bulletin, theannual Brick Awards – which have becomeone of the most prestigious events in theconstruction industry calender – and by BDAtechnical staff, who lecture to schools ofarchitecture and engineering, as well as atCPD events.

The BDA provides comprehensive adviceand information on every aspect of brickconstruction. Architects, engineers,

specifiers and members of the public canaccess a comprehensive resource on thepractical, technical and aesthetic aspects ofbrickwork either by telephone, the website(www.brick.org.uk) or through the extensiverange of BDA publications. BDA staff workon the drafting of technical publications,codes and standards. They represented theindustry on the committees that formulatedthe new harmonised European standards andare currently involved in revisions of thetechnical literature to take account of thenew standards.

Member companies