SECTION 4
BRICKWORK CONSTRUCTION - BUILDABILITY AND POLYCHROMATIC BRICKWORK

4.1 General
4.2 Skill Levels
4.3 Attitude of Contractors
4.4 The Bricklaying Process

4.1 General

Any review of bricklaying practice will of necessity be strong on anecdotal evidence, if thin on empirical data. Having said this, much of the following material gleaned first-hand on sites in discussion with bricklayers, contractors and architects reveals a surprising degree of unanimity about the "how to" of polychromatic brickwork. Perhaps of greater significance than the "how to lay" question is the imperative for architects to better understand the perspective of the bricklaying subcontractor, the head contractor, and the realities of brick supply.

4.2 Skill Levels

Although peppered with highly skilled individiuals, the trade has presented itself to architects with the following inbuilt faults:

• The number of firms and available trowels change dramatically as economic cycles effect the building industry. This volatility is not conducive to skill.
• Even in economic downturns (when firms can be expected generally to shrink back to the best trowels), bricklaying firms in non-domestic work still suffer from inconsistency and unevenness of skill in the rank and file. Apprentices are also seen as too expensive in hard times. Leading hands will at first inspire confidence as early polychromatic work breaks new ground and complex details begin, but this hope is dashed when the workforce is extended.
• The bricklaying trade is sufficiently mobile to make certain parts of New South Wales (e.g. Canberra after 1987) virtually starved of talent when work levels fall. Turnover is higher than desirable to build up a 'body of knowledge' in each city and regional centre.
• To practice as a bricklayer, the appropriate union membership is critical (Construction, Mining, Forestry and Energy Union in New South Wales), but evidence in the form of a licence is not insisted upon. The result is a high proportion of trained-on-the-job bricklayers and a union that, in the past, had no active interest in bricklaying training and skill levels. Contrast this with the venerable bricklaying union in Victoria which insists upon a four-year apprenticeship to achieve accreditation. However, this may be seen by young people seeking to enter the trade as too high a threshold. Lower New South Wales labour costs probably result in more bricks laid per capita: 125 in New South Wales per annum versus 75 in Victoria.

An initiative worthy of support by architects is the re-emergence of bricklaying associations. The Australian Guild of Bricklayers and the Masonry Contractors' Association of N.S.W. have recently been formed in New South Wales. Each seeks to identify and accredit excellence in craftsmanship and to give a service to those jobs where an existing subcontractor cannot achieve the degree of expertise required. However, the initiatives arising largely from the award restructuring process might hold out the best hopes for the future.

4.3 Attitude of Contractors

Rightly or wrongly, head contractors of medium to large-scaled non-residential construction have long regarded bricklaying as a problem trade. The most commonly voiced complaints are that site industrial unrest has been historically prevalent on jobs with a major bricklaying component and that the trade is particularly susceptible to weather delays in an industry increasingly using off-site assembly of dry-enclosure building elements. One obvious repercussion of the above has been the favouring by contractors of certain bricklaying firms because of their industrial and speed track record on previous jobs. Understandable as this is, there is cause for concern that skill level alone is not always of equal concern to contractors as it is to architects.

An added cause for concern, particularly in boom periods, is the attraction to head contractors of tight bricklaying tendering, even to the point of forcing the bricklayer to 'absorb' burdensome extras. For example, a hard-nosed builder may tie a bricklaying subcontractor to a firm price for the works, with no quantification of, or reimbursement for special mortars, brick cutting, half-brick cutting, delays beyond the bricklayer's control and adequate protection of work in progress. Without taking the bricklayer's cause, tendering often proceeds with the bricklaying subcontractor receiving a bill of quantities only (no drawings), or asked to take-off quantities on a limited set of drawings. In recent years it has not been uncommon for bricklaying firms to have pulled out of projects mid-stream, to have forced a change from lump-sum subcontract to 'cost-plus' on a schedule of rates, to have absorbed heavy losses at the cost of quality, or eventually to have been forced into liquidation.

In this short canvassing of the issues, two immediate solutions arise:

• At the risk of limiting the field, architects could nominate select subcontract tender lists for brickwork as is common for trades such as mechanical services;
• Insist, and verify, that both the bill of quantities is fully detailed (see Appendix 2), and that tenderers issue full drawings and details to bricklayers at the time of tender.

4.4 The Bricklaying Process

The following observations of the bricklaying process are made to highlight the interplay of design intent, buildability, and the building process.

Brick selection

Although brick selection for polychromatic work may have been made early, that selection may be questioned as soon as work commences on site. For example, the first few pallet loads arriving on site may differ from the architects rather pristine sample pack provided months earlier by a trade representative. This problem is only avoided by taking the time at brick selection stage to view bricks at least en masse at the brickyard, or built into a previous job, so that design expectations are not shipwrecked on changes of supply or colour and quality variations.

The subtleties of polychromatic work demand that, wherever possible, sample panels should be erected to fine tune all variables at the pre-contract, or immediately post-contract stage. In particular, mortar needs time to dry and to be cleaned off the brick face so the finished effect can be fully understood.

The problem is further complicated if, for example, dry-pressed bricks are used with a bricklayer having little experience in laying them. Obviously, dry-pressed bricks are heavier to lay, may require more rigorous pre-wetting, and are somewhat slower to tamp down to level in the momentum of laying. These matters and the greater degree of handling care to protect arrises compared to extruded bricks needs to be understood by the bricklayer. Attention could be drawn to these matters in the specification. Here is a case for possibly using a select tender list for bricklayers (extendable of course, if the contractor can argue for a firm not on the list), and for clarification at an early stage in the job of the work practices needed for good results.

Where, for any reason, a late change in a brick selection is made it is important to check the physical compatability of bricks, for example, their relative 'e' factors.

It is common for the contractor to order and purchase bricks on projects where colour uniformity is important to the design intent. The architect needs to ensure that the bricks are ordered from the one manufacturer's batch number. This process starts with a firm order from the contractor. The brick manufacturer then reserves the number ordered from a production batch. If, however, the contractor underorders due to a concern to keep cost down, or chooses to order on more than one occasion, the brick manufacturer may be in a dilemma. When a second order is placed (because bricks run out), the additional bricks are invariably taken from another batch. The risk, particularly in a light coloured face brick, is that the second batch will be a different colour. All the above problem can be minimised if the bricklayer sets aside several pallets from each batch. However, if the first batch has been laid, it will not be posible to mix batches and different coloured bands may result when the second batch is laid.

Subtle brick banding

Apart from the problems that lime bloom and staining cause to brick bands of subtly differing hues or tones, some brick ranges vary over time as the clay seam varies. Thus, a sample pack of bricks chosen possibly a year before bricks are laid on site, may differ from the brick produced at the time of ordering. It is thus better to avoid overly subtle banding and err towards bold colour combinations.

Brick size

Communication of priorities in brick design to the contractor and bricklayer is an important ingredient in achieving quality. One example is the issue of brick size. With a medium to dark brick, the brick size may be such that a 'standard' gauge (20 bricks length + 20 perpends = 2400 long; 7 courses = 600mm high) results in a fat joint. If a bed joint width of 10mm is a higher priority than brick gauge (and hence some dimensioning of floor-to-floor levels), then a brick gauge built up from the actual brick size may be necessary (e.g. 7 courses = 590). Another example is the variation in size between light and dark bricks in the one polychromatic wall. Feedback from bricklayers is that architectural specification requirements are often contradictory.

Mortar specification

Where a standard 1:1:6 mix is specified and used, few problems arise on site for mixes using both standard portland cement and off-white cement. (The use of white cement being rare because of its high cost and fickle setting characteristics).

Efforts to introduce a colour to the mortar are usually fraught with danger. Colour additives in the form of oxides are prone to variations which will spoil the finished product unless the whole mortar batch for a project can be dry-mixed in one operation. The latter solution is costly, given the need to allow for wastage. Colouring by oxides is usually undertaken to match or approximate the colour of darker brick in polychromatic work. It must be borne in mind that for the bricklayer the change from one mortar mix to another for a polychromatic band or panel is extremely disruptive to the flow of work. The second problem is that of achieving a reasonable junction between perpends in one colour and bed joints in another. The interface needs to be a raked joint - but even this technique does not eliminate all problems.

With light coloured brickwork, the design intent can be to introduce a cream or ochre colouring to mortar to approximate the brick colour. This can be done by varying the sand source to provide a yellow or ochre to colour.

The following factors are relevant:

• Architects' unfamiliarity with the finer points of available sands and their colour. In a market served mainly by large bulk suppliers of sand and readymix, such information is not easily gained and few architects keep abreast of it.
• A favourably coloured sand may not have the workability of a bricklayer's preferred bush sand and the architecct can become a contributing agent to a less preferred mortar mix and possible second rate work.
• If trials are done within the contract itself (instead of in a pre-contract mock-up), any delays in resolution of the mortar can be costly. Yet again it is a case of pre-contract experimentation.

Lime content

The prevalence of an air entraining agent, e.g. Bycol in mortar mixes (despite its prohibition in specifications) is gradually decreasing as the understanding of its toll on mortar strength and integrity is broadened. However, part of the reason for that use lies in bricklayers' dislike of lime and penchant for slow-setting (economical) mixes, and sometimes an effort to reduce lime bloom at the cleaning stage. Research into the importance of a 1:3 basic ratio of paste to matrix in the 1:1:6 mix, as well as the self-mending properties of lime which minimises unsightly cracking due to brick growth and diurnal expansion, should enhance the future of lime-based mixes, particularly where several brick types are juxtaposed. Some bricklayers prefer slightly less lime in a 1:2:12 mix.

Joint design

Joint design needs to take into account the practicalities of the selected brick and the bricklaying process. For example, a tooled joint of moderate depth will draw attention to the quality of the brick arris. A close inspection of a tuck-pointed facade in Sydney red bricks will reveal fair to poor arrises, masked by the coloured blind mortar, and the whole salvaged by the sharpness of the tuck pointing. In modern work, a flush joint will place demands on brick quality - notably brick arrises, size, consistency and shape. The architect needs to appreciate the implications of all such variables prior to design finalisation.

For example, higher moisture content green bricks may suffer from undulations along the stretcher face between extrusion holes and from lipping outwards along the arris. Other problems associated with extrusion and wire cutting can lead to longitudinal warp, or 'banana' bricks. All of the above - rippling undulation, lipping and warp - will make it extremely difficult for the bricklayer to lay smooth 'ashlar' work when flush joints are specified. By definition, two adjacent bricks will not be uniform along their bed joint. Sidelighting will greatly exacerbate the problem.

• keep to finer grain sands in the mortar mix, but not an all-fine ("Sydney" beach sand) mix, which is too runny to cut;
• strike joints one or two courses behind laying, in order to allow the mortar to go off slightly - this is not easy to enforce;
• allow the mortar to stiffen after striking; then work the joints with a bagging action using carpet or a styrene foam block.

Raked joints are, by comparison, much less problematic.

Brick cleaning

Interrelated with design decisions regarding joints are the problems caused by the brick cleaning process. It is a mark of a good bricklayer that they will tend to keep brickwork clean while laying, leaving little mortar on the face. However, that such care is shown by only a minority. Hence an attitude develops that mortar stains on face brickwork are not of great consequence, as the brick cleaner will fix it. This sloppy attitude, combined with the open surface of most extruded bricks, results in much ingrained mortar left on face brickwork. As brick cleaning has developed in New South Wales as a separate trade, the head contractor will, in many cases, be more anxious about mortar staining than will the bricklayer. Every supervising architect will be familiar with the damage caused to brick faces, fretting of joints and damage to other elements by excessive and rich cleaning at high pressure. The problem will only be resolved when the brick-cleaning trade (it is really little more than an itinerant workers club for the unskilled) becomes trained and licensed or the trade eliminated and cleaning revert to bricklayers.

Techniques such as bagging mortar flush joints (by carpet or polystyrene), while ultimately very successful in the short term, can create difficulties by masking the whole face of polychromatic brickwork with mortar smears. It becomes very difficult for the architect or bricklayer to see the brick quality gauge and check for brick batch colour problems until cleaning is done and when rectification may be too late.

Polychromatic brickwork

Finally, the architect needs to appreciate the impact that polychromatic design has upon bricklaying. The main feedback from bricklayers centres around the effect on momentum and productivity. Each change in brick colour, each corbelled course or change in bond, tends to slow down the momentum which is critical for both the bricklayer's profitability and the programme of the works. To load a second brick colour stack on the scaffold, to mix mortar colour supplied, etc. represent a break in concentration and need for constant supervision.

The supply of bricks from more than one manufacturer is not in itself a problem for the bricklayer. The larger the job, the greater the opportunity for bricklayers to become acquainted with the pattern of polychromatic laying as they move along the 'learning curve'. The key to all of the above is clear documentation of polychromatic details. Ambiguities or lack of cross-referencing of drawings will lead to the bricklayer adopting a 'best-guess' approach, which will assume that patterns in one part of the building are common throughout. Thus both comprehensiveness of detailing and logical consistency in using polychromatic work will be rewarded by good results.