Plastering is smoothing and finishing surfaces on walls, ceilings, and roofs. The aim is to achieve a hard, smooth finish that can be painted, enhancing the appearance of a space.
Let’s look at the different types of plaster finishes, their properties, and where they are best used.
Let’s get straight to the point.
Plaster finishes add texture, character, and durability to walls and ceilings. Common types include pebble dash, scraped, textured, stucco, exposed aggregate, waterproof, smooth coat, sand, rough, and deeper finishes.
Lime, cement, and gypsum are common plastering materials. Each offers distinct benefits, such as flexibility, durability, and ease of application. Plaster finishes also improve moisture resistance, sound insulation, and aesthetic appeal.
Choosing the right finish depends on texture, colour, durability, and acoustics. It enhances a space’s appearance and functionality. Consulting a professional ensures the best result for your needs.
Types Of Plaster Finishes
Plaster finishes are more than just a visual feature—they add texture, character, and durability to a space. Here’s a breakdown of the most common types:
1. Pebble Dash Plaster Finish
A pebble dash finish involves scattering small stones or pebbles over a freshly applied layer of mortar. This method creates a durable, textured surface, often used on exterior walls for its weather-resistant qualities.
- Mix Ratio: Cement and coarse sand at 1:3.
- Application: Pebbles are pressed into a 1 mm thick mortar layer with a wooden float or trowel.
2. Scraped Plaster Finish
A scraped plaster finish involves removing the top layer of plaster after it has hardened with a steel straight edge or similar tool. The scraping process reveals the underlying aggregates, creating a unique, visually appealing and crack-resistant texture.
- Layer Thickness: The final coat is usually 6 to 12 mm, with 3 mm removed during scraping.
3. Textured Plaster Finish
Textured finishes are popular for interior walls because they create striking patterns. Tools like brushes, trowels, and rollers are used to achieve the desired effect on the plaster’s surface.
- Components: Cement, sand, lime, water, and additives like fibres or pigments.
4. Stucco Plaster Finish
Stucco is one of the most durable plaster finishes for exterior and interior use. It typically involves three layers:
- Scratch Coat
- Brown Coat
- Finish Coat
The total thickness usually reaches about 25 mm, providing a strong, long-lasting surface.
5. Exposed Aggregate Plaster Finish
This finish uses colourful marble chips set into a plaster base, resulting in a decorative surface with a rough texture. It’s a popular choice for external walls, adding a touch of elegance.
- Aggregate Size: Marble chips between 6 mm and 12 mm.
- Application: Wet admixture is thrown onto the wall while the base coat is moist.
6. Waterproof Plaster Finish
A waterproof plaster finish is ideal for areas that require extra moisture resistance. A cement waterproof compound is mixed with the plaster to ensure durability and prevent water penetration.
7. Smooth Coat Finish
The smooth coat finish is a simple yet effective technique for producing a flat, polished surface. It involves applying a fine mix of cement and sand in a 1:3 ratio and smoothing it with a wooden float.
8. Sand Finish Plaster
A sand finish plaster gives a matte texture and is commonly used for interior and exterior walls. It typically requires two coats of mortar, with the second layer applied after the first one has dried.
- First Coat Thickness: 12 mm with a 1:4 cement-sand ratio.
- Second Coat Thickness: 8 mm with a 1:3 cement-sand ratio.
9. Rough Plaster Finish
Rough plaster is ideal for adding texture and character to a wall. Its surface is intentionally uneven, and trowels or brushes create distinct patterns.
This finish is commonly used in rustic or industrial-style designs.
10. Depeter Finish
Depeter finishes involve applying a final coat of plaster and embedding decorative elements like coloured gravel or plinths. This technique adds both texture and visual interest to the wall.
Types Of Plaster Based On Material
1. Lime Plaster
Lime plaster is created by mixing sand and lime in a 1:3 ratio. It acts as both an undercoat and a topcoat. To minimise cracking, 5 kg of animal hair is added per square metre of plaster.
Due to its flexibility and breathability, lime plaster is often used for restoring historic buildings.
2. Cement Plaster
Cement plaster, or cement stucco, combines cement, sand, and water. It’s a durable option for both interior and exterior surfaces. It provides a fireproof, weather-resistant, and insect-resistant finish, making it ideal for various conditions.
The thickness can vary, allowing for both smooth and textured finishes.
3. Gypsum Plaster
Gypsum plaster, commonly called Plaster of Paris, is made from gypsum, a calcium sulphate mineral. It’s widely used for indoor applications due to its consistent appearance and affordability.
It can be applied in thin or thick layers and allows quick sanding and painting after application. Its insulation properties help maintain room temperature.
Plaster Background Surfaces
Plaster finishes adhere well to surfaces with rough and firm textures. They can be applied directly to bricks, blocks, or concrete surfaces.
Special techniques are used for surfaces with high water absorption to ensure proper adhesion.
- High-Suction Surfaces: Pre-treat with a liquid primer or water spray for lightweight
concrete blocks.
- Low-Suction Surfaces: Use polymer or polyvinyl alcohol (PVA) bonding agents to improve plaster adhesion.
Choosing The Right Plaster Finish
When selecting a plaster finish, consider the following factors:
- Texture: Choose smooth, rough, or decorative textures based on the room’s style.
- Colour: Plaster finishes are available in various colours, impacting the room’s overall look.
- Durability: Areas with high traffic or moisture exposure require a more robust plaster type.
- Acoustics: Plaster with sound-absorbing qualities can help reduce noise in busy areas.
Benefits Of Different Plaster Finishes
Choosing the right plaster finish offers numerous benefits for a space’s appearance and functionality. Here are some key advantages of different plaster finishes:
1. Durability
- Cement and stucco finishes provide excellent resistance to wear and tear.
- These finishes are particularly effective in harsh weather conditions, offering strong protection against moisture, wind, and temperature changes.
- Cement-based plaster is also fire-resistant, adding a layer of safety to both interiors and exteriors.
2. Aesthetic Appeal
- Textured plaster finishes, such as pebble dash and scrapped plaster, create unique visual effects and add character and style to walls.
- Exposed aggregate finishes use colourful marble chips to create a natural, decorative look that can make a strong design statement.
- Smooth coat and sand finish plasters provide a clean, elegant appearance suitable for modern interiors.
3. Versatility
- Gypsum plaster can be easily applied to various surfaces, making it ideal for thin and thick coatings.
- It offers a smooth finish that can be quickly sanded and painted, allowing for easy changes in décor.
- Textured plaster is adaptable, enabling custom designs with tools and techniques to achieve different patterns.
4. Moisture Resistance
- Waterproof plaster finishes are essential in moisture-prone areas, such as bathrooms, kitchens, and outdoor walls.
- These plasters reduce the risk of dampness, mould, and water damage, ensuring the longevity of the building structure.
- Cement-based waterproofing compounds can be integrated directly into the plaster mix, enhancing the water resistance of the finish.
5. Sound Insulation
- Some plaster finishes, like rough or textured plaster, absorb sound to improve a room’s acoustics.
- This feature makes them ideal for spaces like home theatres, recording studios, or offices requiring noise reduction.
- Selecting the right plaster finish enhances the overall aesthetics and durability, versatility, and functionality of the surfaces in your home or building.
Conclusion
Understanding the different plaster finishes helps you choose the best option for your project. Each finish has unique properties suited to various applications, from interior decoration to durable exterior surfaces.
Consulting with a professional plasterer can ensure the correct technique is applied, resulting in a finish that meets aesthetic and functional needs.
Choosing the right plaster finish enhances the look of your space and its longevity and resilience.
Frequently Asked Questions About Plastering
Is plaster a costly material?
Plaster is more expensive than gypsum. Cement and cement lime plaster are cheaper alternatives. The substance used is chlorine, which is highly toxic in its pure form.
Is white cement the same as plaster?
White cement is not the same as plaster; it has a different consistency. The former, made of gypsum, is used to make casts for medical purposes (such as when repairing a fracture), while the latter is put on walls to make them shine.
Is plaster dangerous to one’s health?
Many people fear working with plaster because of its inherent dangers. Though it is not dangerous in the right hands, the substance is generally considered safe for everyday use. Anything embedded in the plaster runs the risk of being trapped and subjected to extreme heat.
Is plaster suitable to use on walls?
Plaster is the best option for repairing gaps in plaster walls because its properties are more likely to match the wall material. Plaster isn’t often used to repair drywall, but it does a great job of reinforcing interior walls.
Is plaster easy to maintain?
When you want to clean your Venetian plaster walls, all you have to do is wipe them down. In order to lengthen the life of walls, routine maintenance such as cleaning and sealing is recommended.
