Stucco vs plaster. Which is the better option?
Updated: Apr 26, 2021
Stucco is a type of working material made out of cement, sand, water, and lime. On the other hand, plaster is also a type of working material usually made into a powder that is mixed with water to form plaster. When it comes to deciding which is better, we need to look at the pros and cons.
Stucco is usually applied at the exterior of building and houses. It goes from being a thick substance to a rock hard solid. In total it takes 48 hours to dry. Installation can go from $5-9 per sq ft depending on the company. Traditional stucco is made of lime, sand, and water. Modern stucco is made of Portland cement, sand, and water. Lime is added to increase the permeability and workability of modern stucco. Sometimes additives such as acrylics and glass fibers are added to improve the structural properties of the stucco. This is usually done with what is considered a one-coat stucco system, as opposed to the traditional three-coat method. Lime stucco is a relatively hard material that can be broken or chipped by hand without too much difficulty. The lime itself is usually white; color comes from the aggregate or any added pigments. Lime stucco has the property of being self-healing to a limited degree because of the slight water solubility of lime (which in solution can be deposited in cracks, where it solidifies). Portland cement stucco is very hard and brittle and can easily crack if the base on which it is applied is not stable. Typically its color was gray, from the innate color of most Portland cement, but white Portland cement is also used. Today's stucco manufacturers offer a very wide range of colors that can be mixed integrally in the finish coat. Other materials such as stone and glass chips are sometimes "dashed" onto the finish coat before drying, with the finished product commonly known as "rock dash", "pebble dash", or also as roughcast if the stones are incorporated directly into the stucco, used mainly from the early 20th through the early 21st centuries. As a building material, stucco is a durable, attractive, and weather-resistant wall covering. It was traditionally used as both an interior and exterior finish applied in one or two thin layers directly over a solid masonry, Brick, or stone surface. The finish coat usually contained an integral color and was typically textured for appearance. Stucco has also been used as a sculptural and artistic material. Stucco relief was used in the architectural decoration schemes of many ancient cultures. Examples of Egyptian, Minoan, and Etruscan stucco reliefs remain extant. In the art of Mesopotamia and ancient Persian art there was a widespread tradition of figurative and ornamental internal stucco reliefs, which continued into Islamic art, for example in Abbasid Samarra, now using geometrical and plant-based ornament. As the arabesque reached its full maturity, carved stucco remained a very common medium for decoration and calligraphic inscriptions. Indian architecture used stucco as a material for sculpture in an architectural context. It is rare in the countryside. Modern stucco is used as an exterior cement plaster wall covering. It is usually a mix of sand, Portland cement, lime and water, but may also consist of a proprietary mix of additives including fibers and synthetic acrylics that add strength and flexibility. Modern synthetic stucco can be applied as one base layer and a finish layer, which is thinner and faster to apply, compared to the traditional application of three-coat stucco. The repair of historic stucco should begin by identifying the cause of the damage to the stucco finish. Historically, the application of stucco was quite similar to the process of applying lime plaster. Repairs should be carried out as soon as problems become visible, as the damage will only become worse over time. Cracks may form in the stucco due to building settling or direct damage to the exterior coating. Once water is able to breach the coating, whether through an opening in the stucco itself or from beneath its surface, fragile stucco can begin to buckle and crumble. Wood is a common structural material that is often used as substrate beneath stucco. It can absorb moisture from at or below ground level and draw it away from the original source of the problem. Stucco can also be applied to masonry such as brick or stone, which can also be damaged by moisture infiltration. Depending on the extent of the damage to the finish, varying degrees of repairs may be carried out. Small hairline cracks may be sealed with an additional layer of finish coat or even simply a coat of paint. Modern caulking materials are not ideal mediums of repair. Making the choice to patch or completely repair a stuccoed surface depends on the texture of the finish coat. Repairs, especially numerous ones, made to a smoothly finished surface will be more noticeable and recovering the entire surface with a new layer of finish coat may be more appropriate. Conversely, it may be easier to conceal patches of repair work to a textured surface and complete refinishing may not be necessary.
Plaster is a building material used for the protective or decorative coating of walls and ceilings and for moulding and casting decorative elements. In English "plaster" usually means a material used for the interiors of buildings, while "render" commonly refers to external applications. Another imprecise term used for the material is stucco, which is also often used for plasterwork that is worked in some way to produce relief decoration, rather than flat surfaces.The most common types of plaster mainly contain either gypsum, lime, or cement, but all work in a similar way. The plaster is manufactured as a dry powder and is mixed with water to form a stiff but workable paste immediately before it is applied to the surface. The reaction with water liberates heat through crystallization and the hydrated plaster then hardens.
Plaster can be relatively easily worked with metal tools or even sandpaper, and can be moulded, either on site or to make pre-formed sections in advance, which are put in place with adhesive. Plaster is not a strong material; it is suitable for finishing, rather than load-bearing, and when thickly applied for decoration may require a hidden supporting framework, usually in metal.
Forms of plaster have several other uses. In medicine plaster orthopedic casts are still often used for supporting set broken bones. In dentistry plaster is used to make dental impressions. Various types of models and moulds are made with plaster. In art, lime plaster is the traditional matrix for fresco painting; the pigments are applied to a thin wet top layer of plaster and fuse with it so that the painting is actually in coloured plaster. In the ancient world, as well as the sort of ornamental designs in plaster relief that are still used, plaster was also widely used to create large figurative reliefs for walls, though few of these have survived.
Clay plaster is a mixture of clay, sand and water with the addition of plant fibers for tensile strength over wood lath.
Clay plaster has been used since antiquity. Settlers in the American colonies used clay plaster on the interiors of their houses: “Interior plastering in the form of clay antedated even the building of houses of frame, and must have been visible in the inside of wattle filling in those earliest frame houses in which …wainscot had not been indulged. Clay continued in the use long after the adoption of laths and brick filling for the frame." Where lime was not available or easily accessible it was rationed or substituted with other binders. In Martin E. Weaver’s seminal work he says, “Mud plaster consists of clay or earth which is mixed with water to give a “plastic” or workable consistency. If the clay mixture is too plastic it will shrink, crack and distort on drying. It will also probably drop off the wall. Sand and fine gravels were added to reduce the concentrations of fine clay particles which were the cause of the excessive shrinkage.” Straw or grass was added sometimes with the addition of manure.
In the Earliest European settlers’ plasterwork, a mud plaster was used or more usually a mud-lime mixture. McKee  writes, of a circa 1675 Massachusetts contract that specified the plasterer, “Is to lath and siele the four rooms of the house betwixt the joists overhead with a coat of lime and haire upon the clay; also to fill the gable ends of the house with ricks and plaister them with clay. 5. To lath and plaster partitions of the house with clay and lime, and to fill, lath, and plaister them with lime and haire besides; and to siele and lath them overhead with lime; also to fill, lath, and plaster the kitchen up to the wall plate on every side. 6. The said Daniel Andrews is to find lime, bricks, clay, stone, haire, together with laborers and workmen… .” Records of the New Haven colony in 1641 mention clay and hay as well as lime and hair also. In German houses of Pennsylvania the use of clay persisted.”
At the end of the day, plaster seems like the better option but its always your personal choice.