Cracking plaster can be a common yet frustrating issue in new and old buildings. Whether you’re dealing with hairline cracks or larger structural problems, understanding the reasons behind these cracks and knowing how to prevent them can save time, money, and a lot of stress.

Plaster cracking affects the aesthetic appeal of your walls and can indicate deeper issues with your building’s structure or environment. This article will explore the causes of plaster cracking, methods to prevent it, and ways to fix it if it has already occurred.

How Do You Stop Plaster From Cracking?

Understanding The Causes Of Plaster Cracking

To effectively stop plaster from cracking, it is crucial to first understand the underlying causes. Cracks in plaster can occur for several reasons, ranging from natural settling and temperature changes to moisture issues and improper application techniques.

• Settling and Movement: One of the most common causes of plaster cracking is the natural settling of a building. Over time, buildings shift and settle, which can cause plaster to crack, especially if the foundation is not stable. This is particularly common in older buildings but can happen in newer constructions as well.

• Temperature and Humidity Fluctuations: Changes in temperature and humidity can cause plaster to expand and contract. In climates with significant temperature variations between seasons or even between day and night, this can lead to cracks forming over time. Excessive moisture or dryness can cause the plaster to weaken, making it more prone to cracking.

• Poor Quality Materials and Application: The quality of materials used and the method of application can significantly affect the longevity of plaster. Using poor-quality plaster mix, insufficient mixing, or improper application techniques can result in an uneven finish that is more likely to crack. Similarly, applying plaster too thickly or thinly, or not allowing it to dry properly between coats, can lead to cracks forming as the material dries and cures.

• Vibration and Impact: Vibrations from nearby construction work, heavy traffic, or even frequent slamming of doors can cause plaster to crack, especially in areas that are already weakened or have been repaired multiple times. In addition, direct impacts to the wall, such as moving furniture or accidental bumps, can also cause cracks to develop.

Tips For Preventing Plaster Cracking

Now that we understand the main causes of plaster cracking, let’s explore some practical steps to prevent this issue from occurring in the first place.

• Ensure a Stable Foundation: Before applying plaster, make sure that the building’s foundation is stable. If the building is new, allow adequate time for settling to occur before plastering the walls. For older buildings, it may be necessary to reinforce or repair the foundation to prevent future movement and cracks.

• Use High-Quality Materials: Invest in high-quality plaster and mixing materials to ensure a durable finish. Using a plaster mix that is appropriate for your climate and the specific conditions of your building can also help reduce the risk of cracking. Always follow the manufacturer’s instructions for mixing and application to achieve the best results.

• Apply Plaster Properly: Proper application is crucial to preventing cracks. Apply plaster in thin, even coats, allowing each layer to dry thoroughly before adding the next. Avoid applying plaster too thickly, as this can cause it to crack as it dries and shrinks. Additionally, ensure that the substrate (the surface to which the plaster is applied) is clean, dry, and properly prepared to provide a strong bond for the plaster.

• Control the Environment: Maintain a stable environment during and after the plastering process to prevent rapid drying or excessive moisture. Use dehumidifiers or fans in humid conditions, and avoid exposing newly plastered walls to direct sunlight or high temperatures. Keeping the room at a consistent temperature and humidity level will help the plaster dry evenly and reduce the risk of cracking.

• Install Expansion Joints: In larger areas or where there are significant temperature changes, consider installing expansion joints. These are flexible joints that allow for movement and can help prevent cracks by absorbing the stress caused by expansion and contraction.

How To Repair Cracked Plaster

Despite your best efforts to prevent it, plaster cracks can still occur. When they do, it’s important to repair them promptly to prevent further damage and maintain the integrity of your walls. Here’s how to effectively repair cracked plaster:

• Assess the Damage: Before starting any repairs, assess the extent of the damage to determine the best course of action. Hairline cracks can often be repaired with simple touch-up techniques, while larger cracks or areas with multiple cracks may require more extensive repairs.

• Prepare the Surface: Before applying any repair materials, prepare the cracked area by cleaning it thoroughly. Remove any loose plaster, dust, or debris using a brush or vacuum. For larger cracks, widen the crack slightly using a putty knife or a similar tool to create a V-shaped groove. This will help the repair material adhere better and provide a more secure bond.

• Apply the Repair Material: Depending on the size and severity of the crack, choose an appropriate repair material. For hairline cracks, a ready-mixed filler or a thin coat of joint compound can be used. For larger cracks, a more robust patching compound or plaster mix may be necessary. Apply the repair material using a putty knife or trowel, filling the crack and smoothing the surface to match the surrounding area.

• Allow to Dry and Sand Smooth: Once the repair material has been applied, allow it to dry completely according to the manufacturer’s instructions. After drying, sand the repaired area smooth with fine-grit sandpaper to blend it with the surrounding wall. This will ensure a seamless finish and make the repair less noticeable.

• Prime and Paint: After sanding, apply a primer to the repaired area to seal it and prepare it for painting. Once the primer is dry, paint the area to match the rest of the wall. Using high-quality paint and applying it evenly will help conceal the repair and restore the appearance of your wall.

Common Mistakes To Avoid When Dealing With Plaster Cracks

When addressing plaster cracks, it’s important to avoid common mistakes that can make the problem worse or lead to future issues. Here are some key pitfalls to avoid:

• Ignoring the Root Cause: Simply repairing the crack without addressing the underlying cause is a temporary fix. If the cause of the crack is not resolved, the issue is likely to reoccur. Make sure to identify and address the root cause, such as moisture problems or structural issues, before making repairs.

• Using the Wrong Materials: Using inappropriate or low-quality materials for repairs can lead to further cracking and damage. Always use materials that are suitable for the type of plaster and the specific conditions of your wall.

• Rushing the Repair Process: It’s essential to take your time when repairing plaster cracks to ensure a lasting result. Allow adequate drying time between each step, and don’t rush the process to avoid further damage or a subpar finish.

• Not Preparing the Surface Properly: Failing to properly clean and prepare the cracked area before applying repair materials can result in poor adhesion and further cracking. Always ensure that the surface is clean, dry, and free of loose debris before starting repairs.

• Over-sanding the Repaired Area: While sanding is necessary to achieve a smooth finish, over-sanding can cause the repair material to weaken or crack. Use fine-grit sandpaper and sand gently to blend the repaired area with the surrounding wall without removing too much material.

Conclusion

Preventing plaster from cracking requires a combination of good building practices, proper material selection, and careful environmental control. By understanding the causes of plaster cracking and implementing preventive measures, you can maintain the integrity and appearance of your walls for years to come.

However, if cracks do occur, addressing them promptly with the right techniques and materials will ensure a durable repair and prevent further damage.

Whether you’re a homeowner, a contractor, or someone interested in building maintenance, following these guidelines will help you manage and prevent plaster cracking effectively. Remember, a little attention to detail and proactive care can go a long way in keeping your walls in top condition.

Click and read his guide “what causes plaster to crack” to learn more!