Operative Plasterers’ and Cement Masons’ International Association of the United States and Canada (OPCMIA)

OPCMIA represents workers that fall into two major segments: plaster and concrete. Workers in each of these fields generally have multiple specialties to serve niche markets, such as commercial, industrial and residential. Today OPCMIA represents plasterers and cement masons who lay building foundations, cast flat and decorative concrete components, and apply wall finishes, free-form decorative plasterwork and fireproofing.


OPCMIA’s roots can be traced as far back as 1864, during the American Civil War. At that time, it was known as the National Plasterer’s Union, which backed the “Eight Hour Day” movement. In 1887, the union amended its constitution to include Canadian workers. The union officially changed its name to OPCMIA in 1951, after recognizing that union members performed work well beyond just finishing cement.


The trade(s) that are represented by this union include:



11720 Beltsville Drive

Suite 700

Beltsville, MD 20705

United States


(301) 623-1000

International Website