Plastering is the final finish you give your home. Sand and cement are essential ingredients, but additional materials can be added to enhance the quality of plaster.
Plaster increases the beauty and adds a protective layer on the background materials such as bricks and stones. There are different types of plasters based on the ingredients, desired finishes, required proportion, popularity, and the kind of work being done.
Some of the standard plasters available in the market are cement plaster, lime plaster, gypsum plaster, and clay plasters.
Gypsum plaster has grown in usage in recent years, thus replacing cement plasters because it can be applied directly without sand. Further, this plaster doesn’t require curating; therefore, it saves the amount of water needed for the construction.
Purpose of Plaster
There are several reasons why plaster is vital in construction.
- It gives a uniform, clean, and durable surface.
- It covers the brick and stone’s rough surfaces.
- Plaster provides a protective layer against atmospheric effects.
- It strengthens the wall and increases its durability.
- Plastering makes the surface look attractive.
- It covers porous and degraded materials, thus giving the surface a decorative effect.
- Plaster prepares the wall and ceiling for painting.
Brief History of Gypsum Plaster
Gypsum is a white rock containing calcium sulphate dihydrates. It’s used in sculptures, moulds, fertilizers, and as a plaster material.
This Plaster material has been used in the construction industry for many years as a result of its outstanding properties. Thus, Egyptians used this kid of plaster on the Cheops pyramid while the pyramids of Giza proves that this plaster has a higher performance and is durable.
Throughout the years, it is used as an undercoat or finish plaster, and for that reason, the material has replaced cement and lime plasters.
It can serve as a base for quality paint, for it offers a smooth interior finish. Thus, this plaster can be used on both rough or uniform wall surfaces.
Properties of Gypsum Plaster
- This plaster is lightweight; thus, it doesn’t add any weight to the building.
- It gives high flexural and tensile strength.
- Unlike cement plaster, it doesn’t shrink during the hardening or drying process.
- The plaster saves energy due to its low thermal conductivity.
- It prevents rusting of pipes made of metal, thus improving their durability.
- It’s non-combustible because it has a lot of crystal water; thus, gypsum plaster serves as a barrier in the event of a fire.
How to Store Gypsum
You should not expose the surface to moisture after an application of gypsum plaster because water reduces its strength and setting time. Therefore, you should store gypsum bags on a dry, elevated platform made of concrete, brick, or timber.
The plaster should be used within 3-4 months after the date of manufacture; however, you can extend its shelf life if you store it under suitable conditions of humidity and temperature.
Appropriate Gypsum Plaster Thickness
You should apply a thickness of 6-20mm; that means that the walls’ undercoat is 11 mm, the ceiling is 8mm and 2mm for finish coat plaster. Use a minimum of 6mm thickness to prevent cracks.
In cases where plaster thickness beyond 20mm is needed, you can apply a cement, sand and plaster dash coat of 8-12mm first. Follow this up by a gypsum plaster of not less than 6mm thickness. This combination will help you to achieve a smooth finish.
The interior plaster should be 6-12mm thick, and you can achieve it using one coat. The 6mm thickness is applicable in RCC slabs or roofing materials, while 6-1 2mm thickness is for walls.
The exterior plaster should be 18-20mm thick. It’s a two-layered plaster that can have a smooth or sand faced finish.
Category of Gypsum Plaster
This plaster is classified based on the amount of heat that was used during its production.
- Hemihydrate gypsum plaster is produced after heating gypsum above 170°C.
- Anhydrite gypsum plaster is manufactured after heating gypsum up to 170°C.
There are different types of gypsum plaster applications. They include;
- One coat gypsum plaster
- Undercoat gypsum plaster
- Casting gypsum plaster
- Finish gypsum plaster
- Machine applied gypsum plaster.
Advantages of Gypsum Plaster
As stated above, this plaster has been growing in trend and usage in recent years. The following are the reasons why this plaster is causing the cement and lime plaster to lose its market share.
- The cost of applying this plaster is lower due to its time-saving process.
- Application of this plaster has negligible wastage.
- It has higher bonding properties; thus, a single coat on internal bare brick walls, RCC ceilings, concrete columns, and AAC blocks is enough.
- This plaster doesn’t require a curing period like other plaster materials, thus, saving time and water during construction.
- It’s easy to apply, to mould it into different textures and shapes. The quality enhances the aesthetic value of your properties. Further, you can control the setting time of this plaster, and the gap between the two coats is shorter.
- It has a smooth finish that is suitable for all types of paints.
- The plaster doesn’t encourage the growth of fungus, and this type of plaster surfaces are not susceptible to insects’ infestation.
- You can purchase an easy-to-handle pre-mixed gypsum plaster materials, thus reducing the cost and time associated with this plaster application.
- This plaster is economical than other alternatives in places where there is a scarce supply of river sand.
- It has an attractive finish than other plastering materials.
Disadvantages of Gypsum Plaster
- It’s cheaper to apply cement plaster than gypsum plaster for the same thickness.
- This plaster is prone to dampness; thus, it’s not recommended for exterior walls of places like the kitchen, toilet, wash area, and bathroom, among others.
Plastering requires experience and skills to minimize wastage. Bendigo Plastering Services is a registered plasterer that provides a wide range of services. You can contact the company for installation and repair of your ceiling, walls, or exterior services.