Reports on two 19th-century plaster ceilings, one in the First Baptist Church in Portland, Oregon, and the other in the Crocker Art Gallery in Sacramento, California, which were showing signs of rapid deterioration. Plaster and ornamental moldings were separating from the lathwork, and extensive cracks were developing across the ceiling. Instead of removing the original ceiling and replastering, a structural adhesive was used to reconsolidate the deteriorating plaster and lathwork. The structural failure had resulted from the original method of plaster application, with additional stress from vibration and building settlement. The epoxy repair method used in each ceiling is described.