Choosing the right plaster: conventional vs. veneer
Gold Bond plaster products are created to deliver exceptional beauty and durability — what’s the best solution for your project?
Gold Bond Building Products, LLC, an affiliate company of National Gypsum Company, manufactures one of the most complete lines of gypsum plaster products. From conventional plaster base coat and finish options to one- and two-coat veneer plaster systems, Gold Bond® plaster products create high-quality surfaces, enhancing the overall durability of walls and ceilings. This wide array of gypsum plaster provides solutions for some of commercial and residential construction’s most demanding requirements.
“Gold Bond’s plaster products perform well in appearance, sound isolation and fire endurance ratings,” said Mark Chapman, senior manager, construction services at National Gypsum Company. “The versatility and performance of plaster allow architects to design virtually any number of interior ceilings and partitions.”
Let’s explore what makes each type of plaster unique, how they are used and tips for finishing, painting and repairing plaster walls.
What is the difference between conventional plaster and veneer plaster?
The main difference between conventional plaster and veneer plaster systems lies in the overall thickness and application. Conventional plaster is thicker and requires several coats, while veneer plaster is thinner and often requires only one coat.
- Conventional plaster two-coat or three-coat systems range from ½" to ⅞" thick. Conventional plaster systems can be applied over masonry, metal lath or gypsum lath. The ability to apply on metal lath is unique to conventional plaster.
- Veneer plaster one-coat or two-coat systems are no thicker than ⅛". One-coat veneer plaster systems are applied over gypsum lath, while two-coat veneer plaster systems may be applied over masonry or gypsum lath.
The overall application of a veneer plaster is faster and easier than conventional plaster, making it a popular choice for modern construction projects. However, conventional plaster’s additional thickness makes it more durable and longer lasting than veneer plaster, especially in high-traffic areas. In addition, all gypsum plasters are noncombustible and act to prevent the passage of intense heat from fire for extended periods.
"Gold Bond’s plaster products perform well in appearance, sound isolation and fire endurance ratings. The versatility and performance of plaster allow architects to design virtually any number of interior ceilings and partitions.”
Mark ChapmanSenior Manager, Construction ServicesNational Gypsum Company
When to use metal lath vs. gypsum lath
While historic plaster walls and ceilings used thin, wooden lath strips to form a base for applying plaster, modern lath used for a conventional plaster application is most often made of metal or gypsum. Metal lath provides a matrix to which conventional plaster can embed, allowing “keys” to form as the plaster pushes through the holes in the metal to create a mechanical bond.
Gypsum lath, such as Gold Bond® Kal-Kore® Plaster Base, is a durable substrate for both conventional and veneer plaster. Kal-Kore Plaster Base is a tapered-edge gypsum plasterboard with an absorptive face paper designed to permit rapid trowel application and a strong bond of the plaster. For speed of installation, GridMarX® installation guide marks are printed on the face paper.
“Kal-Kore Plaster Base is simple to use and easier to install compared to metal lath,” said Chapman. “Its installation is similar to regular gypsum board and the face paper is specially designed to receive plaster.”
How to apply conventional plaster
A predecessor of drywall, conventional lath and plaster systems, or wet wall systems were once the industry standard in wall and ceiling construction. Today, conventional plaster systems continue to provide smooth, high-quality wall surfaces, regardless of framing alignment.
Common uses of conventional plaster:
- Interior partitions and ceilings
- Radiant heating systems in ceilings
- Sculpting and casting decorative objects
- Historic restoration
Conventional plaster involves applying several layers of plaster to a surface, building up the thickness until the desired level is achieved.
Two-coat work: If using a two-coat conventional plaster system, the base (first) coat is applied to the gypsum lath or masonry base, leaving the surface sufficiently rough and porous to provide a suitable bond of the finish (second) coat. The finish coat can be applied so that it creates either a smooth or a textured surface.
Three-coat work: A three-coat system is generally used with metal lath or direct masonry bases. The scratch (first) coat establishes the bond, or keys, with the base substrate. The brown (second) coat then adds mass and surface to the plaster, followed by applying the finish (third) coat over a partially dry basecoat.
“It is recommended to allow conventional plaster systems to dry for a minimum of 30 days under ambient conditions before final decoration,” noted Chapman. “Variances in humidity or poor drying conditions may affect the drying process.”
Advantages of conventional plaster:
- Provides a smooth, high-quality surface
- Requires no joint taping and finishing
- Resists nail pops better than gypsum wallboard
- Enhances overall wall strength
- Offers high-impact and abrasion resistance
How to apply veneer plaster
Providing high resistance to cracking, abrasion and impact, veneer plaster is a thinner and more modern plastering system. A veneer plaster system consists of a gypsum lath with a special, highly absorptive paper surface that is covered with one or two coats of thinly troweled, special-purpose plaster.
Veneer plaster is ideal for all types of partition and ceiling constructions, including wood framing, steel framing, and furring and masonry.
The same project conditions used in good conventional plastering practice should be replicated when using veneer plaster. However, because veneer plaster coats are thin, particular care must be taken to guard against dryouts (primarily avoiding direct exposure to concentrated sources of heat and drafts).
One-coat veneer plaster: As the name suggests, a one-coat veneer plaster system involves the application of a single layer of plaster over the surface to be finished. This layer is usually thicker than the individual layers of a two-coat system and is applied using a trowel in one initial coat then doubled back over the area bringing it out to the total thickness.
Benefits of a one-coat veneer plaster application:
- Requires only one plastering material for the project
- Has a slightly lower in-place cost than a two-coat system
- Can be applied directly to concrete block with flush or flat joints
Two-coat veneer plaster: With the application of two separate layers of plaster, the base (first) coat is applied as a thin layer over the surface to be finished. Once the base coat has set, the finish (second) layer is applied to provide a smooth and even surface.
Benefits of a two-coat veneer plaster application:
- Has greater crack resistance than one-coat systems
- Can be applied directly to concrete block
For both one- and two-coat veneer plaster, special attention should also be given to the temperature conditions under which the system is installed. For the application of veneer plaster, ensure a temperature of 55 F to 80 F for at least 24 hours before plastering. This same temperature requirement must be maintained for one week after the plaster has set and dried.
Advantages of veneer plaster:
- Rapid installation, reducing overall construction time
- Appearance and surface of conventional plaster at a lower cost
- High resistance to cracking, nail-popping, impact and abrasion failure
- Mill-mixed plaster components that help ensure uniform installation performance and finished project quality
Need to determine what plaster product to use on your next project? Download the Plaster Products Comparison Chart for an overview of all Gold Bond conventional and veneer plaster products.
What is the difference between veneer plaster and a Level 5 gypsum board finish?
A Level 5 gypsum board finish provides a uniform surface and minimizes the possibility of joint photographing and/or fasteners showing through the final decoration. To achieve this level of finish, a skim coat of joint compound is applied over the entire gypsum board surface after applying various coats of joint compound to flat joints, inner angles, fastener heads and accessories.
“A skim coat is essentially a ‘film’ of joint compound — not a readily measurable thickness — that is applied with the intent to conceal minor surface differences and create a more uniform surface,” said Chapman. “Meanwhile, a veneer plaster one- or two-coat system can range from 3/32" to 1/8" in thickness, which provides a monolithic, hard, durable surface.”
How to paint and repair gypsum plaster
As a general rule, under good drying conditions, veneer plaster may be painted 48 hours after application. Conventional plaster, however, will require 30 to 60 days to fully dry before painting. For both conventional and veneer plaster systems, alkali-resistant primers specifically formulated for use over new plaster will permit decorating with oil or latex-type paints. The paint primer should be suitable for use over plaster surfaces that contain lime, which has a high pH of 10–13.
To repair any cracks in the plaster, first brush out cracks to remove all loose material. Small cracks may then be filled flush and feathered out with a setting-type joint compound. For large cracks, apply joint tape and a setting-type joint compound. Mud/craze or alligator cracking caused by rapid drying may be repaired by applying a skim coat of ready-mix joint compound or setting-type joint compound over the affected areas.
Download the Gold Bond Plaster Resource Manual for step-by-step plaster application procedures for both conventional and veneer plaster systems, as well as troubleshooting tips and solutions.
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