When it comes to plastering walls and ceilings, selecting the right material is crucial for ensuring durability, aesthetics, and long-term functionality.
Two of the most popular materials in the Australian market are gypsum plaster and cement plaster.
Both have their distinct advantages and disadvantages, making it essential to understand which option is best suited for your project.
In this article, we’ll explore the properties of gypsum plaster and cement plaster, weigh their pros and cons, and help you decide which material is the best for your home.
Let’s get straight to the point
When choosing between gypsum and cement plaster, the decision depends on the project’s needs.
Gypsum plaster is ideal for interior walls due to its smooth finish, quick setting time, fire resistance, and lack of shrinkage, but it’s not moisture-resistant or durable in high-traffic areas.
Cement plaster, on the other hand, is stronger, moisture-resistant, and more cost-effective, making it better for exteriors and humid environments, though it takes longer to set and has a rougher finish.
Key factors include the location, budget, and desired aesthetics of your project.
What Is Gypsum Plaster?
Gypsum plaster, also known as Plaster of Paris, is a white cementing material made by dehydrating gypsum.
It’s mixed with water to form a paste, which is then applied to walls or ceilings, where it hardens.
Gypsum plaster is primarily used for interior surfaces, providing a smooth, uniform finish that’s ideal for painting and decorating.
Benefits of Gypsum Plaster
1. Fast Setting Time
One of the key benefits of gypsum plaster is its quick setting time. Once applied, it dries much faster than cement plaster, allowing for faster completion of projects.
This makes it a preferred choice for interior projects where time is of the essence.
2. Smooth and Uniform Finish
Gypsum plaster provides a seamless and smooth surface, ideal for interior walls and ceilings.
Its fine texture makes it easier to achieve detailed and decorative finishes, which is highly desirable for interior decoration.
3. Fire Resistance
Gypsum plaster is naturally fire-resistant due to the water molecules contained within the gypsum.
When exposed to fire, this water is released as steam, helping to slow down the spread of flames and offering additional safety for the building’s occupants.
4. Sound Insulation
Another advantage is sound insulation. Gypsum plaster can reduce noise transmission between rooms, making it an excellent choice for areas that require acoustic insulation.
5. No Shrinking or Cracking
Unlike other plastering materials, gypsum plaster is less prone to shrinking or cracking over time. It provides a stable surface that maintains its shape, ensuring a long-lasting finish.
6. Mould and Pest Resistance
Gypsum plaster has natural properties that help resist mould growth, making it a great option for interiors where moisture levels are controlled.
Additionally, its smooth surface leaves no hiding places for pests, adding an extra layer of pest prevention.
Drawbacks of Gypsum Plaster
1. Limited Moisture Resistance
While gypsum plaster is perfect for interiors, it has low moisture resistance, making it unsuitable for exterior use or areas with high humidity, such as bathrooms or kitchens. Moisture can cause cracking and deterioration in gypsum plaster over time.
2. Fragility
Compared to cement plaster, gypsum is more fragile and can be prone to chipping or cracking under impact. This makes it less suitable for high-traffic areas or walls that may experience frequent wear and tear.
What Is Cement Plaster?
Cement plaster is a mixture of Portland cement, sand, and water. It’s widely used in construction for both interior and exterior surfaces.
The mixture is applied to walls to create a strong, durable surface that can withstand the elements.
Benefits of Cement Plaster
1. Durability and Strength
Cement plaster is known for its strength and durability. It can withstand harsh conditions, making it ideal for exterior walls.
Once cured, cement plaster is resistant to cracking, ensuring a long-lasting surface.
2. Moisture Resistance
Unlike gypsum plaster, cement plaster is highly resistant to moisture. This makes it the preferred choice for areas exposed to rain, humidity, or damp conditions. It’s commonly used for exterior walls, bathrooms, and kitchens.
3. Versatility
Cement plaster is highly versatile and can be used on both interior and exterior surfaces.
Its ability to withstand different environmental conditions makes it an excellent choice for Australian homes, especially those located in regions with varying climates.
4. Affordability
Cement plaster is often more cost-effective than gypsum plaster, especially for large-scale projects.
Its widespread availability and lower price make it a popular choice for budget-conscious homeowners.
5. Weather Resistance
Cement plaster is highly resistant to various weather conditions, including wind, rain, and pollution.
This durability ensures that your walls will stand the test of time, particularly in outdoor applications.
Drawbacks of Cement Plaster
1. Long Setting Time
One of the significant disadvantages of cement plaster is its longer setting and curing time.
Cement plaster requires several days to fully cure, often requiring additional water curing during the process to prevent cracks. This can slow down the pace of construction.
2. Rough Finish
Cement plaster naturally has a rough texture, which may not be desirable for interior finishes.
Additional steps, such as punning, may be required to smooth the surface for painting, adding time and cost to the project.
3. Not Fire Resistant
Unlike gypsum plaster, cement plaster is not naturally fire-resistant. It can become brittle and fail when exposed to high temperatures, making it less ideal for interior surfaces where fire safety is a concern.
4. Prone to Cracking
While cement plaster is durable, it can be prone to shrinkage and hairline cracks as it cures.
Over time, these cracks can worsen, potentially leading to moisture infiltration and damage.
Key Factors to Consider When Choosing Between Gypsum and Cement Plaster
1. Application
For interior surfaces, gypsum plaster is often the best choice due to its smooth finish, quick setting time, and fire resistance.
On the other hand, for exterior walls or areas exposed to moisture, cement plaster is more suitable due to its strength and moisture resistance.
2. Climate
If you live in an area with high humidity or frequent rainfall, cement plaster is a better option. Gypsum plaster should be avoided in areas exposed to high moisture, as it can degrade over time.
3. Budget
If you’re working with a tight budget, cement plaster tends to be more cost-effective, especially for large-scale projects.
However, for smaller interior jobs that require a high-quality finish, gypsum plaster is worth the investment.
4. Timeframe
If you’re looking for a quicker turnaround, gypsum plaster sets faster and allows you to start painting or decorating much sooner than cement plaster, which has a longer curing time.
5. Aesthetic Preferences
For a smooth and elegant finish, gypsum plaster is the superior option. Cement plaster may require additional treatments to achieve the desired aesthetic appeal for interiors.
Conclusion
When deciding between gypsum plaster and cement plaster, the choice largely depends on the application, location, and specific requirements of your project.
- Gypsum plaster is best suited for interior walls and ceilings, offering a smooth finish, fire resistance, and quick setting time. However, its limitations with moisture resistance make it unsuitable for outdoor use.
- Cement plaster, on the other hand, is ideal for exterior surfaces due to its durability, moisture resistance, and cost-effectiveness. While it may require more time to apply and cure, it offers the strength needed to withstand Australia’s varied climates.
By considering factors such as project scope, budget, environmental conditions, and aesthetic preferences, you can confidently choose the right plastering material for your home, ensuring long-lasting results and satisfaction.
Frequently Asked Questions
What Is Gypsum Plaster Used For?
Crude gypsum is used as a fluxing agent, fertiliser, paper and textiles filler, and Portland cement retarder.
In addition, about three-fourths of the total production is calculated as plaster of Paris and as building materials in plaster, cement, board products, and tiles and blocks.
Can Gypsum Plaster Be Used In Exterior Applications?
No, gypsum plaster is not suitable for exterior applications. Gypsum plaster has limited water resistance and is more susceptible to damage from moisture and weather conditions.
It is primarily designed for interior use, such as walls and ceilings. For exterior applications, it is recommended to use cement-based plaster or other materials specifically designed for outdoor use.
Does Gypsum Plaster Require Any Special Preparation Before Application?
Yes, gypsum plaster does require some special preparation before application. Before applying gypsum plaster, the surface should be clean, free from dust, dirt, and loose particles.
In addition, it is important to ensure that the surface is dry and stable. In some cases, a primer may be required to improve adhesion.
Any cracks or gaps should also be filled and smoothed out before applying the gypsum plaster. Following these preparation steps helps to ensure a proper bond and a smooth, durable finish.
What Factors Affect The Setting Time Of Cement Plaster?
Several factors can affect the setting time of cement plaster. The main factors include:
- Type of cement: Different types of cement have varying setting times. For example, rapid-setting cement will have a shorter setting time than regular cement.
- Temperature: Higher temperatures accelerate the setting time, while lower temperatures slow it down. Extreme temperatures can lead to issues like quick setting or prolonged drying times.
- Water content: The amount of water used in the mix affects the setting time. Higher water content can extend the setting time, while lower water content can shorten it. It’s essential to follow the recommended water-to-cement ratio.
- Admixtures: Admixtures like accelerators or retarders can influence the setting time. Accelerators speed up the setting process, while retarders slow it down. These additives often adjust the setting time based on project requirements.
- Mixing technique: Proper mixing of the plaster is crucial. Over-mixing or under-mixing can affect the setting time and the overall performance of the plaster.
It is important to consider these factors and follow the manufacturer’s guidelines to achieve the desired setting time for cement plaster.
Can Gypsum And Cement Plaster Be Used Together In A Project?
Yes, depending on the specific requirements and application areas, gypsum and cement plaster can be used together in a project.
Each plastering material has advantages and limitations, and its use can be determined based on the project’s needs.
