STABILIZING SAN ANTONIO'S
SPANISH COLONIAL MISSIONS
Mission San Juan Capistrano, 1851, by Herman Lungkwitz. Courtesy San Antonio Museum Association.
The task of stabilizing San Antonio's Spanish Colonial Missions,
symbols of our heritage and examples of our area's earliest buildings, is
made more complex by the fact that their lives as buildings reflect many
changes and alterations. The final sites we see today were preceded by
others. Once the sites were selected, there is evidence that earlier
buildings were abandoned and the foundations built-over in an organic
process of shifting and changing in response to the forces, internal and
external that comprised the vitality at the heart of the Missions. At the end
of the Mission Period when the churches were abandoned and the lands
given to the Mission Indians, this process continued as the compounds
served as quarries, repositories for cut stone used in nearby buildings. The
Mission walls expanded as rooms were added within the walls, and
contracted as stones were removed for use elsewhere. Mission Concepci6n
served as a cattle barn. The Granary at San Jos6 housed several families.
Neglect following abandonment left the forces of nature free to wear away
at the structures, so that by the latter part of the Nineteenth Century, all
the Churches except Concepci6n and San Jos6's Sacristy had lost not only
their roofs but also important sections of their walls as well.
As their use as Churches was revived, the subsequent restorations and
reconstructions of the Nineteenth and Twentieth Centuries that produced
what we see today have been incorporated into the ongoing lives of these
structures.
Tracking and integrating the building sequences into an overall
understanding of the structures is important to the preservation of the
Missions through a comprehension of the manner in which the forces of
the various building sequences play upon one another. A structures survey
has recently been completed and information about the early Mission
construction is coming to light through the translation of original Mission
records microfilmed in Queretero and Zacatecas. Selected archaeological
exploration has also helped reveal the building sequences, however some
questions still remain. With what is known, both from research and
physical evidence, every effort is made to keep all of the interventions in
the structures in balance.
As efforts are made to stabilize these precious resources, many
factors that contribute to their deterioration are addressed.
Water, architects' oldest enemy, heads the list, attacking the
buildings from above as well as below. Leaking roofs, flashings and
parapets have allowed rain to insidiously undermine the surface as well as
the internal binding of the walls. San Jose's Sacristy ceiling was almost
completely ruined by the leaking roof. Faulty drain connections through
the parapets to the canals at San Jos6 caused water to saturate enormous
sections of the walls. Part of the wall of the bastion at Mission Espada
was near collapse due to roof failure that caused water to erode the
dirt/mortar infill, destroying the tie between the interior and exterior
wythes of wall. In this case the damage was so severe that danger of
collapse was imminent. The threatened portion of the structure was
recorded, disassembled and reconstructed.
Domed roofs present unique problems. Their shapes cause
conventional roofing and flashing methods to fall short of being
satisfactory. Plaster was the original cover and remains so on Mission San
Jose's reconstructed dome and the original one at Mission Concepcion
The Sacristy domes at San Jose, three, with low profiles surrounded by
parapets, and large relatively flat areas presented a difficult roofing
challenge. The high maintenance of plaster in this more vulnerable
location forced other solutions to be sought. Urethane roofing and flashing
with a "breathable" silicone coating has proven to be successful.
These are but a few examples of a planned program aimed at
addressing the above-grade sources of moisture penetration that has been
in effect for over 10 years. Roofs have been replaced or patched, canals
repaired, lined and extended from the walls. Asphalt and plant life have
Bexar County Historical Foundation
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