There is often confusion around the difference between render and plaster, and in which situations they should be used. Whether you’re building a new home or renovating, knowing the difference between these two products will help you when you’re trying to find a qualified renderer or plasterer. To understand how they’re different, it’s important to first understand why the two processes are often confused.
How are rendering and plastering similar?
Cement render and plaster are both a type of mortar coating applied over blockwork to create a more smooth, even surface. While the usage of cement render and plaster aren’t quite the same, they are made using the same ingredients, which are a mixture of cement, sand, water and sometimes lime.
Rendering vs plastering
What differs between these products is the amount and consistency of the ingredients included in the mixtures. Render is made with more cement than plaster and is therefore thicker, due to the fact that it needs to be weather resistant as it’s used on the outside of buildings. On the other hand, plaster uses less cement, as it’s used on internal walls and is not exposed to the effects of wind, rain, and sun, so doesn’t need to be as strong. Plaster usually is made from finer sand, while render consists of more coarse sand. This is because plastering is done before the application of paint, to provide a smooth surface to prepare for an even paint finish.Premixed renders also often have added polymers and other special rendering compounds to further increase their durability and resistance to water, preventing the render from cracking and chipping on impact.
When to use render
As previously mentioned, the difference in the consistency of render and plaster is due to their different strength requirements for their unique usage.Cement rending,acrylic rendering and polymer rendering are used on external walls for a number of reasons:
- To enhance the appearance and texture of external surfaces
- To change the colour of external walls or surfaces
- To repair cracks in external walls
- To increases the value of a property
- To add an extra layer of insulation to walls
- To waterproof and fireproof a building
- To reduce long-term maintenance costs
The increased strength of the render, due to the higher percentage of cement and more coarse sand, is beneficial for these purposes of repairing external walls and protecting them for many years. When blockwork is exposed to harsh conditions, they are prone to cracking or crumbling, becoming soft under pressure. A rendering specialist will be able to apply render in the most effective way to keep your home or project in the best condition.Rendering for outside walls is completed by laying the render in sheets, then applied using a trowel and then finished with a variety of tools, depending on the preferred finish. Many people prefer a smooth, flat appearance, while others opt for a textured, patterned finish. This comes down to taste and the need for the render to complement the rest of the property.
When to use plaster
In contrast, plaster is used on internal walls and ceilings only, to create the smoothest finish possible. This is because when smooth, it is much easier to clean and decorate the walls with paint or wallpaper. This clean finish is the perfect way to enhance the aesthetic appearance of the inside walls of a building.Plaster must be completely set and dry before the surface has paint or wallpaper applied to it. Drying time is recommended from a week to a month, before the application of decorating material. When a freshly plastered wall is dry, there will be no noticeable dark spots, and the whole surface will be a consistently light colour. There are several factors which contribute to the drying time of plaster, including the number of layers of plaster, and environmental conditions including the weather and internal heating and cooling.Plaster is also water repellant and easily cleaned, making it perfect interior wall coating for families who have children who are prone to touch or draw on walls. In older buildings with walls that were originally made from mud or clay, the application of plaster materials was also used to make the internal walls fire resistant.