Architecture of The California Missions - Construction Methods

Construction Methods

The earliest projects had a layer of streambed stones arranged as a foundation, upon which the adobes were placed. Later, stone and masonry were used for foundation courses, which greatly added to the bearing capacity of the brickwork. Aside from superficial leveling, no other ground preparation was done before construction started. There is some evidence to indicate that the initial structures at some of the outposts were produced by setting wooden posts close together and filling the interstitial spaces with clay. At completion, the building would be covered with a thatched roof and wall surfaces would be coated with whitewash to keep the clay exterior from eroding. This type of construction is known as "wattle and daub" (jacal to the natives) and eventually gave way to the use of adobe, stone, or ladrillos. Even though many of the adobe structures were ultimately replaced with ones of piedra or brick, adobe was still employed extensively and was the principal material used in building the missions as there was an almost universal lack of readily-available stone. The adobes were laid in courses and cemented together with wet clay. Due to the low bearing strength of adobe and the lack of skilled brick masons (albañils), walls made of mud bricks had to be fairly thick. The width of a wall depended mostly on its height: low walls were commonly two feet thick, while the highest (up to thirty-five feet) required as much as six feet of material to support them.

Timbers were set into the upper courses of most walls to stiffen them. Massive exterior buttresses were also employed to fortify wall sections (see the photo at right), but this method of reinforcement required the inclusion of pilasters on the inside of the building to resist the lateral thrust of the buttresses and prevent the collapse of the wall. Pilasters and buttresses were often composed of more durable baked brick, even when the walls they supported were adobe. When the walls got too high for workers on the ground to reach the top, simple wood scaffolding was erected from whatever lumber was available. Many times posts were temporarily cemented into the walls to support catwalks. When the wall was completed, the posts were removed and the voids filled with adobe, or were sometimes sawed off flush with the surface of the wall.

The Spaniards had various types of rudimentary hoists and cranes at their disposal for lifting materials to the men working on top of a structure. These machines were fashioned out of wood and rope, and were usually similar in configuration to a ship's rigging. In fact, sailors were often employed in mission construction to apply their knowledge of maritime rigging to the handling of loads. It is not apparent as to whether or not the padres used pulleys in their lifting devices, but these instruments nevertheless got the job done. Unless adobes were protected from the elements they would eventually dissolve into nothing more than heaps of mud. Most adobe walls, therefore, were either whitewashed or stuccoed inside and out. Whitewash was a mixture of lime and water which was brushed on the interior surfaces of partition walls; stucco was a longer-lasting, viscous blend of aggregate (in this case, sand) and whitewash, applied to the faces of load-bearing walls with a paleta (trowel). Usually the face of a wall that was to receive stucco would be scored so that the mixture would adhere better, or laborers would press bits of broken tile or small stones into the wet mortar to provide a varied surface for the stucco to cling to.

Once erection of the walls was completed, assembly of the roof could commence. The flat or gabled roofs were held up by square, evenly-spaced wood beams, which carried the weight of the roof and ceiling (if one was present). In the sanctuaries it was common for beams to be decorated with painted designs. Vigas rested on wood corbels, which were built into the walls and often projected on the outside of the building. When the rafters were in place a thatch of tules (brush) was woven over them for insulation, and were in turn covered with clay tiles. The tiles were cemented to the roof with mortar, clay, or brea (tar or bitumen). At some of the missions the padres were able to hire professional stonemasons to assist them in their endeavors; in 1797, for example, master mason Isidoro Aguílar was brought in from Culiacán, Mexico to supervise the building of a stone church at San Juan Capistrano. The church, constructed mostly of sandstone, featured a vaulted ceiling and seven domes. Indians had to gather thousands of stones from miles around for this venture, transporting them in carrettas or carrying them by hand. This structure, nicknamed "Serra's Church" once had a l20-foot-tall bell tower that was almost totally destroyed by earthquake in 1812.

Arched door and window openings required the use of wood centering during erection, as did corridor arches and any type of vault or domed construction. Windows were kept small and to a minimum, and placed high on walls as a protective measure in case of Indian attack. A few of the missions had imported glass window panes, but most made do with oiled skins stretched tightly across the openings. Windows were the only source of interior illumination at the missions, other than the tallow candles made in the outposts' workshops. Doors were made of wood cut into planks at the carpintería, and most often bore the Spanish "River of Life" pattern or other carved or painted designs. Carpenters used a ripsaw (or "pitsaw") to saw logs into thin boards, which were held together by ornate nails forged in the mission's blacksmith shop. Nails, especially long ones, were scarce throughout California, so large members (such as rafters or beams) which had to be fastened together were tied with rawhide strips. Connections of this type were common in post and lintel construction, such as that found over corridors. Aside from nails, blacksmiths fashioned iron gates, crosses, tools, kitchen utensils, cannons for mission defense, and other objects needed by the mission community. Settlements had to rely on cargo ships and trade for their iron supplies as they did not have the capability to mine and process iron ore.