Plaster is one of the oldest types of building materials used in home construction and can be made from lime, clay or gypsum. The type of plaster used varies, based on the age of the home or the architectural design period. For instance, many Victorian homes often included a mixture of mud and straw with clay plaster and wood. Homes with chipped, broken or falling plaster require immediate repair, especially when the plaster is on the ceiling.
A building's age helps to identify the type of plaster used. To determine the age of your home before digging into the walls, start with researching home documents. For instance, many homes built in the 1930s used a combination of wood lath and plaster as a base for the walls. If you don't have any of the home's documents handy, the local recorder's office in your city or county will have historical information on the home.
Professional Home Inspection
A professional home inspection can determine the type of building materials used in construction as well as the age of the home when you can't access historical documents. Gypsum-based plaster, because of its strength created during heating or burning process of its manufacture, could be used on either the exterior or the interior of the home. Very old homes often had horsehair mixed with lime plaster for its exterior wall coverings. Clay plaster mixed with straw and mud was hand-applied over woven wood.
By identifying the support materials used in construction, you can usually identify identify the plaster type. The type of support materials include gypsum board, wood and expanded metal lath or mesh. For instance, plaster of Paris, a gypsum-based plaster, was typically used in combination with lathing or over masonry or brick. When crumbled, plaster of Paris turns into a fine dust, as there are no other elements present within the plaster. Today's modern plasters come in a variety of colors, including pink, brown or gray and use adhesion to stay on the cladding material as opposed to the suction method used with older plaster types.
Locate an out-of-the-way area to conduct a test to determine the type of plaster used. A good area is the attic. Check for an area where the plaster is in disrepair or falling off the walls. This allows you to look at the wall and determine the support backing and type of plaster used. Scrape a small bit of plaster from the wall and examine it closely for sand and horsehair in lime or calcite-based plaster. High-tech methods include taking a sampling for a laboratory analysis.
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