Architecture of The California Missions - Building Materials

Building Materials

The scarcity of imported materials, together with a lack of skilled laborers, compelled the Fathers to employ simple building materials and methods in the construction of mission structures. Since importing the quantity of materials necessary for a large mission complex was impossible, the padres had to gather the materials they needed from the land around them. Five (5) basic materials were used in constructing the permanent mission structures: adobe, timber, stone, brick, and tile. Adobes (mud bricks) were made from a combination of earth and water, with chaff, straw, or manure added to bind the mixture together. Occasionally pieces of bricks or shells were placed in the mix to improve the cohesiveness. The soil used may have been clay, loam, or sandy or gravelly earth. The making of the bricks was a simple process, derived from methods originally developed in Spain and Mexico. A convenient, level spot was chosen near the intended building site and close to a suitable water supply (usually a spring or creek). The ground was dug up and soaked with water, whereupon bare-legged workers would stomp the wet earth and binders into a homogeneous consistency fit for carrying to, and placing in, the brick molds.

The mixture was compressed into the wooden formas, which were arranged in rows, and leveled by hand to the top of the frame. From time to time, a worker would leave an imprint of his hand or foot on the surface of a wet brick, or perhaps a literate workman would inscribe his name and the date on the face. When the forms were filled, the bricks were left in the sun to dry. Great care was taken to expose the bricks on all sides, in order to ensure uniform drying and prevent cracking. Once dry, the bricks were stacked in rows to await their use. California adobes measured 11 by 22 inches (280 by 560 mm), were 2 to 5 inches (51 to 130 mm) thick, and weighed 20 to 40 pounds (10 to 20 kg), making them convenient to carry and easy to handle during the construction process.

Facilities for milling lumber were almost non-existent: workers used stone axes and crude saws to shape the wood, and often used logs which only had their bark stripped from them. These methods gave mission structures their distinctive appearance. Timber was used to reinforce walls, as vigas (beams) to support roofs, and as forms for door and window openings and arches. Since most of the settlements were located in valleys or coastal plains almost totally devoid of suitably large trees, the padres were in most cases limited to pine, alder, poplar, cypress and juniper trees for use in their construction efforts. Indians used wooden carrettas, drawn by oxen, to haul timber from as much as forty miles away (as was the case at Mission San Miguel Arcángel). At Mission San Luis Rey, however, the ingenious Father Lasuén instructed his neophyte workers to float logs downriver from Palomar Mountain to the mission site. The lack of good-sized timber forced the men to design mission buildings that were long and narrow. For example, the widest inside dimensions of any of the mission buildings (at San Carlos, Santa Clara, and Santa Cruz) is 29 feet (8.8 m): the narrowest, at Mission Soledad, spans 16.2 feet (4.9 m). The longest structure, at Mission Santa Barbara, stretches 162.5 feet (49.5 m). Stone (piedra) was used as a construction material whenever possible. In the absence of skilled stonemasons, the inexperienced builders resorted to the use of sandstone; though easier to cut, it was as not weather-resistant as that which would have been used by skilled artisans. To bind the stones together, the priests and Indians followed the (Mexican) Pre-Columbian technique of using mud mortar, since mortar made from lime was unavailable to them. Colored stones and pebbles were added to the mud mixture, giving it "a beautiful and interesting texture."

Ladrillos (conventional bricks) were manufactured in much the same manner as adobes, with one important difference: after forming and initial drying, the bricks were fired in outdoor kilns to ensure a much greater endurance than could be achieved through merely sun-drying them. Common bricks typically measured ten inches (250 mm) square and were 2 to 3 inches (51 to 76 mm) thick. Square paving bricks were equal in thickness to the common variety, but ranged from 11 to 15 inches (280 to 380 mm) across. Many of the structures erected with this type of brick remained standing long after their adobe counterparts had been reduced to rubble.

The earliest structures had roofs of thatch or earth supported by flat poles. Tejas (roof tiles) were utilized in later construction (beginning around 1790) to replace the flammable thatch. The semicircular tiles consisted of clay molded over a section of a log was which well-sanded to prevent the clay from sticking. According to the accounts of Father Estévan Tapís of Mission Santa Barbara, some thirty-two Native American males were required to make 500 tiles each day, while the women carried sand and straw to the pits. The mixture was first worked in pits under the hoofs of animals, then placed on a flat board and fashioned to the correct thickness. Sheets of clay were then placed over the logs and cut the desired to size: they ranged in length from 20 to 24 inches (510 to 610 mm), and tapered from 5 to 10 inches (130 to 250 mm) in width. After trimming, the tiles were dried in the sun, then placed in ovens and burned until they took on a reddish-brown coloring. The quality of the tiles varied greatly among the missions due to differences in soil types from one site to another. Legend has it that the first tiles were made at Mission San Luis Obispo, but Father Maynard Geiger (the Franciscan historian and biographer of Junípero Serra) claims that Mission San Antonio de Padua was actually the first to use them. Aside from their obvious advantage over straw roofs in terms of fire retardance, the impermeable surface also protected the adobe walls below from the damaging effects of rain. The original tiles were secured with a dab of adobe and were held in place because of their shape, being tapered at the upper end so they could not slide off one another.