Investigation, Analysis, and Treatment Testing for the Mission Church, Tumacácori National Historical Park

The adobe mission church (circa 1801) at Tumacácori National Historical Park in Arizona was damaged in an intense winter storm in 2010. To mitigate the damage and to address building envelope vulnerabilities, investigators completed a study of the hygrothermal behavior of the dome, including characterization of soluble salts and environmental conditions that result in salt damage, identification of structural and seismic vulnerabilities, performance testing (lab and in situ) of lime-based renders for exterior surfaces of the church, and an assessment of structural wood. Hygrothermal modeling of the dome indicates that heavy rain events that occur every 5–10 years result in moisture infiltration and damage to the decorated plasters on the dome interior. The structural assessment identified conditions requiring repair, strengthening, and/or improvements that will result in improved ductility of building assemblies. The wood assessment identified species and grade of structural wood members that require repair, reinforcement, or replacement for developing seismic retrofit designs. Natural hydraulic lime (NHL)–based stuccos offer the best combination of performance properties, resistance to erosion, low absorption and debonding, and acceptable flexural strength and water vapor transmission.