Reasons Why Failing to Properly Prepare a Wall can Cause Render Failure

Render is a type of exterior wall finish that provides protection from the elements and enhances the look of the walls. It is commonly used for external walls, such as those on houses and commercial buildings. The render is usually applied over a base coat of plaster, which helps to ensure adhesion and provide insulation to protect against extreme temperatures.

contractor preparing the wall surface for rendering

How Do You Prepare a Wall Before Applying Render?

Before applying render, it’s important to properly prepare the wall. This includes removing any existing loose paint or debris, filling in any holes or cracks with mortar or cement, and ensuring good drainage by sloping the surface away from buildings (to prevent water pooling).

It’s also important to make sure that the wall is free of contaminants, as any residue may prevent the render from adhering properly. This could include oil, grease, or other substances that could be released by paint or plaster during application.


What Can Happen if You Don’t Prepare a Wall Properly?

Failing to properly prepare a wall before applying render can lead to serious problems down the line. If there are any contaminants present on the surface of the wall, they can cause issues with the adhesion of the render and ultimately lead to failure. Additionally, poor drainage can cause dampness which will weaken the bond between the render and base coat.

Inadequate preparation can also lead to a number of other issues, such as cracking and crumbling. This is because render needs to be applied in even layers over smooth surfaces; any irregularities on the wall will result in an uneven finish that won’t last very long.


How Can You Avoid Render Failure?

The best way to avoid render failure is by ensuring proper preparation before application. It’s essential to make sure that the surface of the wall is clean, dry, and free from contaminants before proceeding with the render. Additionally, you should check for any holes or cracks that need filling and slope the surface away from buildings for good drainage.

It’s also important to use the right type of render for your specific project. Different types of render are designed to suit different environments, so it’s important to choose one that is suitable for the conditions. Finally, make sure you follow all the manufacturer’s instructions carefully when applying the render.



Failing to properly prepare a wall before applying render can lead to serious issues in the future, such as cracking and crumbling over time. To ensure a long-lasting finish, it’s essential to make sure that the surface is clean and free from contaminants, with good drainage and no irregularities. Additionally, make sure you use the right type of render for your project and follow all manufacturer’s instructions carefully during application.