Plaster vs Render: What’s the difference?

There are two different methods to cover walls, when should you use which?

Plastering and rendering are both the process of covering walls. The main difference in the two practices is that plastering refers to coating the interior walls, whilst rendering is the coating of exterior walls. The major distinction between plastering and rendering is the strength of the materials used in each. Nonetheless, plaster and render are both made from the same building materials of cement, sand, water and lime gypsum.

Rendering

Rendering is used to coat exterior surfaces of buildings and contains a higher percentage of cement within its composition. Rendering is applied to the outside of buildings to not only make the outside facade more visually appealing, but also provides waterproofing and fireproofing efficiencies.

Rendering is composed of lime gypsum, sand and cement, bonding agents, drying additives and colouring. Lime gypsum is key to giving the coating its creamy appearance and smooth finish. Finer sand must be used in the rendering mixture to create the coveted smooth finish.

Render is layered onto exterior walls in sheets, applied with a trowel, and finished with a number of different tools depending on the desired finished appearance. Rendering can either have a smooth, flat finish or a textured, patterned appearance, determined by the homeowners’ personal taste.

It’s recommended to use the services of a qualified plasterer to complete rendering work for your home, as it takes a skilled hand to achieve professional results. 

Rendering is used for external walls. Source: Shutterstock

Plastering

While plaster is also applied by a plasterer, it differs to render as it contains less cement in its composition, and is used to coat the interior walls and ceilings of buildings so they will be smooth and flat for painting or wallpapering.

Plaster must be set and completely dry before walls are painted or decorated. Freshly plastered walls should be left to fully dry for at least one week to a month before painting. You can tell that freshly plastered walls are completely dry when there are no dark patches visible, and a light uniform colour is apparent across all walls. There are also other factors at play that will affect drying time of plaster such as the number of layers of plaster used, central heating, and seasonal weather. Make sure your home is properly ventilated during the drying stage, open windows and doors to allow for natural ventilation. Be aware that newly plastered walls that dry too quickly are subject to cracking..