12TH INTERNATIONAL

BRICK/BLOCK Masonry c O N F E R E N C E

THE EXPOSED BRICK WAll

M.S. Camino Olea Architect. Valladolid . Spain

ABSTRACT

Cam

This paper discusses various techniques which have been used to simula te the appe-arance of wall bonding in exposed brickwork.

Key words: Finish, exposed bond.

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In the construction of bearing walls for buildings over the centuries, care had to be taken to lap the masonry units in such a way that they formed a single element. To accomplish this, the fundamental rule which had to be observed was that each of the vertical joints between bricks on a course had to be covered by a brick on the course above. This was the case both on the face of the wall and on its width . It was not, however, necessary to set the brick in a precise position, which is the main difference with regard to bonded brickwork, where the bricks are set in such a way that the cross joints on non-consecutive courses are on the same vertical Ii-ne. In bonded brickwork, each brick must be placed in a specific location.

Prior to the 19'h century, these walls were constructed using bricks moulded ma-nually at brickyards. Because they were made by hand, the bricks tended to have notable variations of dimensions and warpage on the face. Thick mortar joints ten-ded to be used; where the walls were left exposed, it becomes clear on observan-ce that bonding was rarely used and that the bricks were instead lapped (Plate 1).

In the second half of the 19'" century, bricks began to be manufactured at pug mills. These bricks, as well as pressed bricks, had a better regularity of sizes and shapes and the faces were more nearly parallel. As a result, walls with bonding could be constructed using very thin joints, and the bricks on the wall face were left exposed.

For exposed brick facades, the preference was for pressed brick, or fine brick, with recessions on the top and bottom surfaces of the brick where the mortar

P/ate 1. Exposed brickwork at the Church of San Andrés in O/medo (Val/ado/id Province) . c. 18th century. The brick was manufactured manual/y.

jommg bricks could be set, thus leaving the joints hidden. Previous attempts had been made to achieve the precision with which walls using this type of brick were constructed (Plate 2), with joints measuring from two to five milli-meters and a regular bond. Other brick types were tried, as were a variety of techniques. Examples of these techniques may be seen in particular buildings and in descriptions found in treatises and manuais on architecture and cons-truction .

The techniques may be divided into two categories: the first category includes those methods which sought to regularize the dimensions of the joints and the exposed face of the brick; the second includes those techniques which attempted to simulate this finish using various facings.

Plote 2. Residential building with a facode af pressed brick. A heading band has been used and the jaints are hidden. Plaza de la Fuente Darada in Valladalid, d. 7908.

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Plote 3. Costillo de Coca in 5egovio.

The first category includes the technique of gauging, which consisted in cut-

ting and smoothing the face of the brick, as Benito Bails describes in the Dic-

cionario de Arquitectura Civil (Dictionary of Civil Architecture) . Bails defines

gauging as:

Shaping the bricks which wil/ farm part af a building ar wall ta the same width and

thickness by rubbing them and cutting them with the brick axe, which is called gau-

ged wark ar gauging.

P/ate 4. Brick walt with protruding joints and the remains of a rendering simu/ating a brick bond. Convent of Santa Brígida in Valtado/id. Latter part of 78th century.

In the Arte de la Albafiilería (Art of Masonry), Juan de Villanueva defines gauged brick as:

8rick which has cut and rubbed to reduce it to the some size as ali others.

Gauging was used when the brickwork was to be left visible, or exposed. It was also used in cases where a facing was to be applied later.

The other technique consisted in constructing the brickwork using recessed or racked joints, and subsequently rejointing the wall with protruding joints. In this

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Plate 5. 8rickwork with protruding joints at the Museum of Natural Sciences in Val/adolid. The brick was manufactured at a pug mil/. c. 1930.

case, the bed joints were aligned and the cross joints were at regular distances. Ali joints were of the same thickness. In the Manual dei Albafíil (The Bricklayer's Manual), Ricardo Marcos Bausá describes this process when speaking of the tech-niques that can be used to give brickwork an attractive appearance:

Once the brickwork is constructed, if the bricks on the outside face of the wolf are to be left visible, the trowel is run olong the joints of eoch of the courses, extrocting the mortor to a certoin depth; this gop is then filfed with finer mortor, hydroulic mortor; the bed ond cross joints are equolfy trimmed so thot on inspection they hove the so-me thickness ond the courses are more regular; this is colfed tuckpointing.

Examples of this technique can be found at buildings such as the 15'h-century Castillo de Coca in Segovia. Buildings constructed in later centuries also provide examples of this technique, though in the 20th century, protruding joints appear to have fallen out of use (Plates 3, 4, 5).

The second category includes rendering, used to simulate a brick bond. Following this method, the joints were laid out in mortar over a wall which had been ren-dered in red with greater precision than the joints on the supporting brickwork (Plates 4, 6).

One technique, which was actually a combination of severa I of the techniques mentioned here, involved gauging the brickwork, painting it with red ocher, and tracing the joints with lime. This is described by Benito Bails in De La Arquitectu-ra Civil (On Civil Architecture):

Plote 6. The rendering on this facode simulates brickwark. P/aza Mayar in Valladalid.

After the work of gauging, the wall was painted with red ocher and the joints were traced in lime ... or, the brick walls could be plaster-coated on both faces, though, it is best to leave the bricks on the outside face of the building exposed, since the bed joints and cross joints make a pleasant sight if they are laid well. To trace the bed joints and cross joints, a coat of red ocher is applied to the visible parts of the wall and the cross joints are marked with grout.

Another technique, which was used in the latter part of the 19th century and the early part of the 20 th, consisted in facing a wall with ceramic units which simula-ted a heading bond made of pressed brick. The most commonly employed de-sign had the dimensions of six headers with the corresponding joints. The lateral edges were toothed, simulating the toothing of a bonded brick wall.

Ali of the above-mentioned techniques would appear to indicate that the regular and precise appearance of bonded brickwork was highly valued, simulations ha-ving been attempted using a variety of methods.

SELECTED BIBLlOGRAPHY

B. Bails. Tomo IX, Parte I que trata De La Arquitectura Civil. Madrid, 1796.

Edición facsímil, Colegio de Aparejadores y Arquitectos Técnicos de Murcia, Murcia 1983.

B. Bails. Diccionario de Arquitectura Civil. Madrid 1802.

P.c.. Espinosa. Manual de Construcciones de Albafiilería. Madrid, 1859.

F. Ger y Lobez. Manual de Construcción Civil. Madrid, 1869.

R. Marcos Y Bausá. Manual dei Albafiil. Madrid, 1883.

P. Perier y Gallego. Tesoro de Albafiiles. Madrid, 1853.

A. Rebollo Matías. Revista Ayuntamiento de Valladolid. Noviembre 1996.

J. A. Ruiz Hernando. La arquitectura de ladrillo en la provincia de Segovia, siglos XII y XIII.

J. de Villanueva . Arte de la Albafiilería. Madrid, 1827. Editora Nacional, Madrid 1974.

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