11th INTERNA TlONAL BRICKlBLOCK MASONRY CONFERENCE

TONGJI UNIVERSITY, SHANGHAI, CHINA, 14 - 16 OCTOBER 1997

HOW THIN IS TOO THIN? Economics and Durability of the New Thin Brick Veneer Systems

Linda Brock I

1. ABSTRACT

Due to market competition from lower cost and more quickly erected c1adding systems there is increasing pressure for the development of more economical fired c1ay brick c1addings. Masonry has historical1y been an important building material, providing both structure and enclosure, although today in Canada and the United States fired clay/shale brick is used primarily as a veneer. Recently a number of attempts have been made to further decrease the cost of masonry c1adding. Many brick buildings, which often appear to be load bearing, in fact no longer even have an anchored veneer system of standard sized brick with a drainage cavity. What appears to be brick is only a thin fired c1ay/shale "tile" adhered to the building. North America appears to be a leader in the development of these new ultra-thin veneers with an interest in exporting the systems. However the following questions arise: How thin is toe thin? What is the long term economic impact of these products when durability is evaluated? Are these systems suitable for a world­wide marke.t? In an attempt to answer these questions this paper traces the beginnings of thin veneers, then analyzes several of the new thin brick systems.

2. INTRODUCTION

Since the earliest times, veneers of stone or materials resembling stone have been used to enhance the appearance or durability of a structure. The Egyptians faced sun-dried c1ay brick pyramids with limestone veneers and later the Romans faced brick buildings with marble and plaster. At the beginning of the nineteenth century in London, brick buildings were stuccoed and lined to resemble stone. ln the early 1970' s, with advances in stone cutting technology, thin anchored stone veneers of less than 50 mm (2") were used as c1adding in high-rise construction. One example, the 32 mm (1-1/4") Carrara marble that c1ad the Amoco Building in Chicago, met with disastrous results. The effect of using such thin marble, exposed to the atmosphere, was not adequately considered. The marble was eventually replaced with a granite veneer. Today rare stones are available in thicknesses as thin as one centimeter bonded to less expensive marble or travertine. One can also obtain stone bonded to a metal honeycomb backing material in a system that can weigh 80% less than solid stone. [I]

Keywords: Thin Brick; Brick Veneer; Precast; Building Envelope

1 Associate Professor, School of Architecture, lhe University of British Columbia, Vancouver, B.C., Canada, V61 1Z2.

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2.1 Fired Clay Brick Veneer

Fired clay brick has also been a popular choice for cladding. Even the Romans, who were not noted for their use of decorative brick, clad the Castra Praetoria (AD 21-23) with brick. This may be the first public building constructed of concrete and so clad.[2] With load bearing masonry walls, the exposed brick faces were originally part of the wall--the face brick being held in compression from the gravity loads of the floors and roof above. Later in England, in the interest of comfort, the exterior wythe of the load bearing masonry wall was pulled away creating an insulating cavity. By the 1850's, 80% of the workers' houses in Southampton were reportedly of cavity wall construction with composite action between the "veneer" and the structure.[3] Today many brick veneer systems have non-masonry backup walls. The only gravity loads on the brick veneer come from the weight of the single story veneer panel itself. These developments have been prompted by the desire for increased function and lower cost while still maintaining the "look of brick."[4]

2.2 "The Look of Brick"

In meeting the demands ofthe post World War II construction boom in the United States and Canada, a plethora of economical systerns were developed including non-masonry materials that appeared to be masonry. A 1967 House and Home magazine article on new products talked about "The look of brick: Now you can have it in aluminum, fiberglass , or verrniculite. All three materiaIs can be used both indoors and outdoors, and all are said to even feel like brick." A present-day example of this concept is an exterior insulation finish system with a brick profile face; the "look of brick" created with a cementitious acrylic stucco applied over expanded polystyrene foam insulation, concrete, or masonry. According to the manufacturer's literature it is " ... suited for alI climatic conditions from hot deserts to icy mountains to rainy tropics."[5] The thinnest "brick" veneer in existence may be a paint system noted in Japan. The concrete substrate is coated with a high quality e1astomeric paint. Self-adhering stencils, creating the desired bonding pattem, are applied. Then a second color is sprayed over the first. When the stencils are removed the base coat color is visible as the mortar joints while the second coat delineates the brick. This offers a durable and economical coating system, and one with considerably reduced potential for life threatening failures .

2.3 Thin Fired Clay Brick

Although thin fired-clay tiles have been used since very early times--traditionally adhered to masonry or concrete structures as decoration--few were intended to imitate a brick wall. One of the earliest attempts to produce a thin fired clay product that, when installed, gave such an appearance occurred in eighteenth century England. These so-called "mathematical tiles" of fired clay, a few centimeters in depth, were developed to circumvent brick tax laws. They were nailed, shingle style, on wood battens to give the impression of a wall of brick.[6] The lower half of the tile was molded to resemble a standard sized brick while the upper half comprised a nailing lip over which the next tile would be laid. After the tiles were nailed to the structure, the joints were mortared. Special comer pieces completed the ruse. Although it enjoyed some popularity as a frre resistant cladding for wood fnime construction, the system fell out of favor when all brick tax laws were repealed in the 1850's. Today similar thin brick shingles of concrete are being produced in Canada.

With the above exception, the use of fired clay "thin bricks" is relatively new. During the 1950's the Brick Institute of America (BIA), then called the Structural Clay Products Research Foundation, developed a system called "SCR Re-Nu-Veneer." In this system a 19 mm (3/4") fired clay tile was attached to the substrate with special clips. Although applicators had been licensed to seU the system, work was stopped after several years . According to BIA, the system was originally developed for the reveneering and remodeling markets.[7]

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2.4 Thin Veneers and Economics

In the Canada and the United States the use of fired c1ay brick as c1adding exists as part of a cavity walI system using a backup wall of concrete masonry, concrete, steel studs, or in the case of some residential construction wood studs. For the past decade the literature has been fulI of articles warning designers of problems with potentially compromising systems. For example, an article in Architectural Record titled "A Veneer Too Thin" referred to the failure ofbrick veneer over steel studs.[8] However, these concems have not and will not stop the move to create even less expensive fired c1ay masonry c1adding options.

The new thin brick veneers are premised on the c1aim that appearance and durability have :lOt been compromised. As one manufacturer so aptly states on the World Wide Web, one can have " ... durability, strength, energy efficiency and good looks - and ali this at a competi tive price."[9] The economics of a thinner c1adding make sense. If the weight is reduced, the cost of the materiais, installation and supporting structure is also reduced. Furthermore, many building and zoning codes measure to the outside c1adding face when determining the area of a buildíng. If the width of the exterior wall can be decreased, the amount of selIable or leasable space increases. A recent study in British Columbia, Canada noted that for high-rise buildings in the City of Vancouver, the use of a brick veneer cavity wall over a thinner face sealed c1adding system can cost the developer up to $3500 (Canadian) per suite in lost, selIable space.[IOL

Thin bricks often form part of prefabricated panels which may also have value added such as increased thermal resistance through the incorporation of rigid insulation or increased durability through the bricks being cast into concrete panels. Advantages also exist in construction. Prefabricating panels increase quality control and allow for year-round construction. Often scaffolding is not needed nor are large on-site material storage areas. Highly skilIed brick masons are unnecessary as many systems can be fabricated and installed by lower skilled and thus lower paid trades people.

Because of the value added, as welI as the decreased weight, an export market exists for many of the systems, particularly in the housing market. Several years ago Japan comprised 75% of the market for a thin brick over rigid foam system with the manufacturer's first sales occul7ing in the hostile environment of Hokkaido.[lI] This same system is used by a company that selIs prefabricated homes from Iceland to Saudi Arabia advertising that they offer, in addition to aluminum, wood and vinyl siding--"a quality brick altemative."[12] This altemative being 406 mm x 1220 mm (16" x 48") pane1s weighing approximate1y 14 kg (31 Ib.), that have a fired c1ay brick face and provide the thermal resistance of a meter thick brick walI (RSI= 1.53, R=8.7).

Thin brick veneers make good economic sense if they maintain or enhance the market appeal as welI as the durability of a properly designed and constructed brick veneer cavity wall. Sales figures indicate that market acceptance is not a problem. The real issue is one of durability. Do these systems make economic sense when examined on the basis of longevity?

3. THIN BRICK VENEER SYSTEMS

This paper covers thin fired c1ay/shale brick systems which have been designed to imitate a brick wall. It does not cover thin brick, terra cotta, or cerarnic tiles that are adhered directly to the structural substrate with either thin-set or thick-set methods. Nor is it intended to be inclusive of ali systems marketed in Canada and the U.S. This paper summarizes the most common systems presently marketed that are primarily intended for exterior use on new residential and non-residential construction. Those reviewed are marketed over a large geographical area.

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3.1 System Components

The basic components of the thin brick veneer systems are the thin brick, the backing material and the support/spacers that hold the brick in place until it is bonded to the backing material. Installation of prefabricated paneIs and finishing of the veneer system may require additional components.

Thin Brick A fired clay/shale thin brick is generally 9.5 mm to 19 mm (3/8" to 3/4") thick. Most systems stipulate that the brick meet or exceed the requirements for type FBX (when tight tolerances are important), severe weather grade, for general use in exposed exterior walls as set forth in ASTM CI088, Specificationfor Thin Veneer Brick Units Madeform Clay or Shale . The thin brick may be formed by the extrusion method and have a keyed back to aid in adhesion, or it may be sliced from a larger clay colurnn. Manufacturers can supply two and three sided comer pieces and offer a variety of shapes, colors, and textures. Some brick manufacturers produce "brick slices" that are wire-cut directly from green brick. The brick body and the slice are firedtogether to stabilize the slice. Standard brick is sometimes split into two "thin brick" for facing pre-cast concrete panels.

~acking Material The backing material provides support for the thin brick and rigidity for prefabricated panels. Common backing materials for prefabricated panels and field installed systems are rigid foam insulation, sheet metal and concrete. Foam insulation and sheet metal may additionally be backed with a rigid sheathing. If concrete is used as the backing material it may also function structurally as in the case of tilt-up paneIs.

Support/spacer Grid Support/spacers keep the thin brick in place until it is affixed to the backing material. A grid of these support/spacers may be the size of one brick or as large as 1220 mm x 2440 mm (4' x 8') . In vertical applications the brick must be supported to assure consistent spacing. The support/spacer grid for backing materials of rigid foam insulation or metal sheets is integral with the foam or metal and remains part of the system. Brick support/spacer grids used with concrete are meant to be removed after the concrete is cast.

3.2 Systems with Integral Rigid Foam Insulation or Sheet Metal Backing and Support/Spacer Grid

When the backing material is integral with the support/spacer grid, as is the case with rigid foam insulation and metal panels, the mastic or adhesive is applied to the backing material. Then the thin brick are placed in the grid from the exterior side. Mortar is then applied between the brick and the joints are pointed. The support/spacer is designed not to interfere with the mortar joint and in some cases reinforces the joint. . Generally the panel, whether pre-manufactured or fabricated on-site, functions solely as face sealed cladding with the only structural function being the transfer of lateral loads. These systems can be applied over a variety of structurally sound, flat substrates including steel and wood stud walls and concrete block.

3.2.1 Rigid Foam Insulation - Field Installed The backing material for these systems usually consists of extruded polystyrene thermal insulation of varying thicknesses. The face of the tongue and groove 1220 mm x 2440 mm (4' x 8' ) foam insulation boards has a vacuum formed styrene skin molded to form horizontal spacers which hold the btick in place. In one system the spacers are discontinuous, providing a drainage pathfor any water that may accumulate behind the brick. The insulation is usually attached to the substrate over a water barrier such as building felt or a spun polyolefin building paper. One system is screwed directly through

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the face of the insulation with an oversized plastic washer. Another screws though a crimped galvanized steel clip which creates a permanent mechanical connection between the mortar, the brick, and the structure. After the insulation is attached, adhesive is applied, and the thin bricks are snapped into the grid. The width of the head joint is determined by the installer. The installation is completed by applying mortar in the bed and head joints, tooling, and cleaning the face.

3.2.2 Rigid Foam Insulation - Prefabricated Panels One of the systems discussed above can also be prefabricated. Brick can be applied, in the factory, to 406 mm x 1220 mm (16" x 48") extruded polystyrene insulation panels. The first panel is attached to a starter angle. Then successive rows are supported by angle clips. Connections to the structural substrate are made in the joints between brick. The final steps are the same as those required for field installations: applying mortar in the bed and head joints which conceals the connections, tooling the joints and finally cleaning the face.

Interlocking 406 mm x 1220 mm (16" x 48") panels comprise another common prefabricated system are that, once in place, requires no additional on-site work. The panels are composed of thin brick adhered to rigid, polyurethane, thermál insulation, bonded to exterior grade plywood or cement board. Mortar is factory applied to the head and bed joints. The first row of pane1s are fastened in place supported on a continuous angle. Subsequent panels then overlap concealing the connection. The panels interlock to create a water tight self-sealing joint.

3.2.3 Metal Panels - Field Installed and Prefabricated Panels Less common are backing materiais of metal, the usual choice being galvanized stee!. With the prefabricated systems the brick is adhered to the metal panel at the factory. The metal sheet has punched tabs that hold the brick in place during installation and then form a permanent lock between the panel and the mortar and brick. Prefabricated panels can be backed witha variety of materiais ineluding plyweod, Figid foam iRsulation.G~ment-board or gypsum board if desired for rigidity, thermal insulation or fire protection. The metal panels vary in size from 406 mm x 1220 mm (16" x 48") to those of a system that uses 1220 mm (48") wide sheets in heights up to 2440 mm (96"). The tabs on one system space the brick both vertically and horizontally. This same system has an embossed surface to provide a better bonàing surface for both the mortar and mastic as well as incorporating a built-in weep system on both sides of the metal pane!.

With ali systems a mastic is applied to the metal panel and the bricks are locked in place either at the factory or on-site after the metal panel has been attached to the structural substrate. Mortar is then applied to the installed panel and tooled.

3.3 Systems with Concrete Backingand Removable Support/Spacer Grids

With these systems the support/spacer grid, which is on the exterior of the veneer, is removed after the thin brick has been cast in the concrete. No mortar is necessary as the mortar joint, formed by the grid, consists of the concrete. After the gIjd is removed the veneer is cleaned, and the installation is complete. The spacers in the grid stop the majority of the cement paste from reaching the face of the thin brick during casting. There are several ways of assuring that any cement paste that does reach the face will not adhere including the use of concrete retarder papers in the grid or coating the face of the 'brick with retarders or paraffin. Precast applications can be grouted first if a coloredmortar joint is desired. The precast panel may function solely as cladding or can serve as the structural wall as in the case of tilt-up panels.

3.3.1 Precast Concrete Panels Precasting of panels allows for repeated use of the support/spacer grids, generally elastomeric liners. The liners for one system measure 1220mm x 2440mm (4' x 8'), have a Shore A-55 durometer hardness and come with a backing of plywood for ease of attachment to precast beds and to assure squareness. Protrusions ftom the liner form the

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mortar joints and provide a seal that stops the cement paste from reaching the face of the brick. The fit between the thin brick and the liner is very important and the brick must hold to tight tolerances in size.

Another similar system uses projecting fins on the joint seals to prevent any cement paste from reaching the brick face. The flexible seals have a Shore A-80 durometer hardness and are bonded to a base of Shore A-30 durometer hardness. Buttons on the base elevate the face of the brick creating a paste reservoir. F1exible side seals, coupled with the paste reservoir, allow for the use of brick with greater irregularities in the size. This system does not include a plywood backing

With both systems the reusable Iiners are attached to the fonning bed, the thin brick are inserted, reinforcing is placed and the concrete casto The paneI is then lified and the liner is reused. Ofien the liner will last through 100 reuses. These systems offer complete design flexibility in the coursing and size of brick and joints.

Precasters also use wood supportlspacer grids and hand place thin brick with rubber joint strips of Shore A-60 durometer hardness. These applications are generally not marketed as a system and thus are not included in this review. The hand placing of brick and joints is time consuming and wooden molds offer less flexibility than other systems.[13] Prefabricated panels, consisting of thin brick in a thick-set cementitious grouting bed on a gypsum sheathed, steel stud wall, are produced in many areas although not marketed as a system.

3.3.2 Site Cast Concrete Walls The supportlspacer grids for cast-in-place concrete walls and tilt-up panels are generally designed for single use due to the economic need to cast large areas simultaneously. One system uses single plastic trays in which one thin brick has been placed. These trays are snapped together at the job site. The system is also available in a 660 mm x 1220 mm (2'x4') plastic grid with the thin brick inserted on site. The face of the brick it is coated with paraffin to prevent cement paste from adhering. The grid, with bricks in place, is attached to the forrn work, reinforcing is placed and the concrete is cast. After the tilt-up panels are in place, or the forrn work is removed from vertical installations, the grid is stripped and the face c1eaned with pressurized hot water to remove the paraffin.

4. ECONOMICS

The cost advantages of systems with integraI supportlspacer grids and backing materials of rigid foam insulation or metal panels are realized by the speed of installation and the use of semi-skilled trades people. Pre-fabrication of the panels can further decrease installation costs and lengthen the construction window. Cost savings also come about as a result of the reduced weight of the systems. Most of these thin brick systems, with integral support/spacer grids, cost less than conventional brick veneer. Savings are even more apparent when the cost of added value such as therrnal insulation is considered. The economic compromises come in regard to the durability and longevity of the system.

The cost of precast concrete paneIs, where thin brick are used solely as ciadding, may be higher than conventional brick veneer however it also offers potentially increased durability. The cost difference decreases with the standardization of the panels and the height of the building. In areas of high seismic activity these systems may be the only viable option for brick c1adding. There are also cost savings when the panels forrn the structural wall as is the case with cast-in-place walls and tilt-up.

5. DURABILITY

These thin brick c1adding systems must be considered as an integral part of the building envelope--mediating the environment to provide safe and healthy Iiving spaces. To do this

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the wall must stop water, control water vapor and air movement, control thermal transmission, transfer structuralloads and accommodate differential movement. Fire and acoustics are also considerations.

The cladding may be designed to stop alI water penetration at the exterior face as in the case of face-sealed systems. In the drain screen approach a cavity behind the cladding allows for any moisture that does penetrate the surface to be drained to the exterior by a flashed weeping system. The water barrier at the back of the cavity provides a second line of defense. A rainscreen is similar except that the pressurr- is equalized between the exterior and the cavity furtber stopping the penetration of moisture. This is accomplished by installing a continuous air barrier, sealed at alI penetrations, and dividing the cavity into chambers sized to eliminate air movement. [ 14] The cladding must also transfer lateral loads to the structure and be able to accommodate differential movement between the structure and the cladding materials. Differential expansion of the cladding materials and the potential damaging effects of pollution and ultraviolet radiation must also be considered.

5.1 Face-Sealed Systems

Most systems using insulation or metal as the backing material rely on a face-seal to stop water. The one c:;xception may be a sheet metal system that clairns there is drainage on both the interior a'nd exterior of the panel. Test data from several systems indicated a perm rating of close to one, _ the number commonly used to denote a vapor barrier. Any water that does penetrate the thin brick cladding comes up against what is essentially a vapor and water barrier formed by the styrene skin of the insulation, the metal, the mastics, or a combination of the above. This means that the thin brick cladding may be continually wet which could lead to potential damage through freeze-thaw of the brick, degradation of the mortar joints, and loss of bond between the brick and the backing material.

Problems also arise with moisture from the interior. In Canada and most of the United States the vapor drive is commonly from the interior to the exterior during the colder months. With residential wood or steel frame construction polyethylene is the most common choice for a vapor barrier. The intent is to stop diffusion of water vapor before it reaches its dew point where it would condense. In reality vapor barriers are more accurately called vapor retarders, and in many cases, are severely compromised or missing. They are often not used in commercial construction. And the larger, more serious problem is moisture laden air carried through the wall. A structurally supported air barrier is necessary to stop this movement but is even less apt to be found in standard construction. Face-sealed systems generally do not function as air barriers due to the panelized installation. Thus water vapor can traveI freely through the wall until it meets what is now functioning as a vapor barrier on the cold side of the insulation. Given the right conditions, moisture laden air can condense throughout the system culminating in corrosion of fasteners, steel studs and reinforcing steel; degradation of batt insulation, exterior sheathing and interior finishes; and rotting of wood frarning.

Transfer of lateral loads is direct for positive loading but relies on mastics and fasteners to transfer negative forces. This presents two areas for problems. First the thin brick can be pulled off the wall. Although much lighter than conventional brick they still pose a life safety hazard. The larger concern might be in the weakening of the face-seal. Continued lateral loading in combination with differential movement can compromise the face-seal, and once moisture gets into the system there is no drainage system to carry it back to the exterior.

5.2 DrainIRainscreen Systems

Precast concrete panels with thin brick cladding generally incorporate cavity construction. Although the brick facing will stop the majority of water from the exterior, there is a second line of defense for moisture that does traveI either through the panel -by diffusion or through the joints due to pressure differentials in the case of drain screeris. ' The cavity

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behind the panels will allow for quick drying of any moisture that might accumulate, and a water barrier at the inside face of the cavity will stop further penetration. Water vapor from the interior due to incomplete vapor and/or air barriers will not be stopped. Both the brick and the concrete allow for water vapor diffusion as there are no "hidden" vapor barriers in the system. If properly designed moisture from the inside will be carried to the cavity before condensing.

Using concrete as the backing material solves several problems mentioned above. First the adhesion of the brick to the concrete appears to be superior to systems using a mastic. For example, testing of bond from brick to foam or metal backing indicates it takes from 317 to 360 kg (700 to 800 Ib.) force to pull the thin brick from the pane!. One test of brick to concrete bond indicated that ..... the apparent point of failure was in the brick itself, as the layer bonded to the epoxy [used to bond a steel cross-plate for the testing apparatus] pulled away from the rest of the brick."[15] There have been few reported failures of thin brick coming loose when integrally cast in concrete. Finally, the stability of the concrete panel greatly reduces the possibility of problems created by differential movement.

6. CONCLUSIONS

For the domestic markets of Canada and the United States, the future of thin brick systems is based on the poiential for increased performance and/or decreased cost over conventional brick veneer cavity wall construction. Marketing the systems globally depends on systems which are light weight and offer added value and increased performance and/or decreased cost over other available cIadding systems. Exportation of field installed systems and prefabricated paneIs using rigid foam or metal backing materials is common, particularly to countries without a thriving brick industry such as Japan. Pre-cast concrete panels are generally not exported because of weight, although there is an export market for the supportlspacer girds ando possibly the thin brick.

Face-sealed systems have the potential for serious problems. The City of Vancouver has experienced many building envelope failures on mid and high-rise residential buildings with face-sealed stucco and EIFS systems.[16] The City has responded by issuing bulletins that will require "drainlrainscreen" construction of ali cIadding systems with detail design and inspection by a certified building envelope specialist.[17]

Precasting of thin brick into a concrete panel appears to have solved the majority of these problems if the wall on which they're used is properly constructed. There are no covert vapor barriers in the precast panel. The permeance of brick and concrete allow the panel to breath similarly to the traditionalload bearing masonry wall. Adhesion of the thin brick is excellent, and if a brick does become dislodged, the function of the wall is not compromised. Acoustic and fire properties are superior. A wide range of options exist for construction of the backup wall , particularly when the panels are attached directly to the colurnns and beams. This backup wall can then act as the secondary line of defense for water as well as fulfill the building envelope requirements for thermal, vapor, and air transfer. (Note that thin brick, when site-cast in structurai walls, requires an interior wall be constructed to provide the necessary thermal and moisture retarders.)

Construction occurs off site, scaffolding is not necessary nor are large on-site storage areas. The only readily apparent disadvantages of precast brick cIadding systems are the weight, thickness and cost. However, it is expected that over a 20 to 50 year period, a well designed precast concrete panel with thin brick would prove to be more economical than the face-sealed systems with backing of foam insulation or metal sheets. However if the cost of additional insulation and lost floor area are considered, as well as a much shorter life expectancy for the building such as 10 to 15 years, the systems with insulation may be more cost advantageous.

With ali systems the design of the building should offer protection from exterior and

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interior moisture sources. Overhangs will greatly reduce the amount of water from exterior sources. However this is only a solution for low-rise construction in less dense areas. Panel design can also help shield criticai joints from water entry.

There are numerous thin brick veneer systems as well as hybrids with advantages and disadvantages to each depending on the local conditions. Most systems have test data indicating adequate performance of the thin brick c1adding systems but not when combined with actual conditions created by the installation. For both domestic and global markets it is necessary that someone take the responsibility to look at the entire wall given the c1imatic conditions of the region, configuration of the building and structural loading. These issues are not being addressed by the manufacturers of the various systems and the question begs asking, is anyone designing these walls?

If this responsibility is not addressed and face-sealed systems are not modified to provide some degree of secondary drainage and water protection, the answer to the question of how thin is toe thin may be the thickness of the thin brick itself. It is the opinion of this author that, presently, the only reliable systems with the potential for a 50 year life are properly designed conventional brick cavity walls and thin brick cast integrally with concrete.

7. REFERENCES

I. Magazine of Masonry Construction UNew Products", The Aberdeen Group, Addison, Illinois, February 1997, p.1l3.

2. Plumridge, A. and Meulenkamp, W., Brickwork. New York: Harry N. Abrams, Inc., 1993, p.16.

3. Elliot, C.D., Technics and Architecture. Cambridge, Massachusetts:' MIT Press, 1992, p.49.

4. Brock, L., uThe Contemporary Brick Wall", Proceedinl1s of the 10th Intemational Brick and alock Masonry Conference. Calgary, Alberta, Canada, 1994, pp. 856-866. This paper provides additional history of the brick wall.

5. Promotionalliterature on UUltra-Tex Finish". Dryvit Systems, Inc. Publication 3-96-lüM.

6. Lloyd, N., A History ofEnglish Brickwork, New York: William Helburn, Inc., 1925, pp. ll,25.

7. uThin Brick Veneer Production - 28C, Reissued February 1990". Technical Notes on Brick Construction, BIA, Reston, Virginia. .

8. Archjtectural Record, UA Veneer Too Thin", March 1989, pp. 116-119.

9. Website ofUniversal Therrno Briques Inc. http://WWW>CAM>ORGI-utb

!O. F.S.R. Study Consultatjon. Prepared by the Masonry Institute of British Columbia for the City of Vancouver, November 9, 1995.

I!. UFirrns Nailing Down New Market", The Globe and Mail Newspaper, Toronto, Ontario, Canada, Sept. 8, 1993, p.B I.

12. uBoost Profile and Enhance Look with Insulated Brick Siding", Buildinl1 Systems Builder, October 1992, p.33.

13 . Freeman, S., UClay Product-Faced Precast Concrete Panels", PCI Journal, JanuarylFebruary 1994, pp.20-36.

14. Ruggiero, S.S. and Meyers, J.C., UDesign and Construction of Watertight Exterior Building Walls", Water in Exterior Buildinl1 Walls' Problems aod Solutions ASTM STP 1107. Thomas A. Schwartz, Ed., Arnerican Society for Testing and Materiais, Philadelphia, 1991. This text is a good source for inforrnation on moisture problems.

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15 , "Survey of Building Envelope Failures in lhe Coastal Clirnate of British Colurnbia" Canadian Mortgage and Housing Corporation, Novernber 22, 1996,

16, City of Vancouver, Bulletin 96-02 dated July 30, 1996, "Performance Requirernentl. for Wall Cladding Systerns [Olher lhan EIFS--see Bulletin 95-09] and Bulletin 96-25 dated Novernber 5, 1996 [Supplern.:nt to 96.02 dated July 30, 1996], "New Building Envelope Design Requirernents" ,

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