How to Repair Cracks in Plaster Walls

Plaster walls add charm and character to any home, but over time, they can develop cracks. These cracks not only affect the aesthetic appeal of your walls but can also lead to more significant structural problems if left untreated. However, repairing cracks in plaster walls is a task that you can tackle yourself with the right tools and techniques. In this article, we will guide you through the process of repairing cracks in plaster walls step by step.

Cracks in Plaster Walls

Before we dive into the details of repairing cracks in plaster walls, let’s first understand what causes these cracks and the tools and materials you’ll need for the job.

Understanding Plaster Walls

Plaster walls are made of a mixture of gypsum, sand, and water. They have been used for centuries due to their durability and versatility. However, plaster walls are prone to cracking due to various factors such as settlement, temperature changes, and humidity.

Causes of Cracks in Plaster Walls

There are several reasons why cracks may appear in plaster walls. Understanding these causes can help you determine the appropriate repair method. Some common causes of cracks in plaster walls include:

  1. Settlement: Over time, the foundation of a building may settle, causing stress on the walls and resulting in cracks.
  2. Temperature and Humidity Changes: Fluctuations in temperature and humidity levels can cause plaster walls to expand and contract, leading to cracks.
  3. Poor Installation: Improper installation techniques, such as inadequate curing time or improper mixing of the plaster, can contribute to cracking.
  4. Structural Issues: If the cracks in your plaster walls are severe or recurring, it may indicate underlying structural problems that need to be addressed.

Tools and Materials Required

Before you start repairing the cracks in your plaster walls, gather the necessary tools and materials. Here’s a list of what you’ll need:

  • Putty knife
  • Sandpaper
  • Plaster adhesive
  • Plaster of Paris
  • Joint compound
  • Fiberglass mesh tape
  • Paintbrushes
  • Primer
  • Paint

Preparing the Surface

Before you can start filling the cracks, it’s essential to prepare the surface properly. Here’s how you can do it:

  1. Clean the area around the cracks using a damp cloth to remove any dust or debris.
  2. Use a putty knife to widen the cracks slightly. This will help the filler adhere better.
  3. Sand the edges of the cracks with sandpaper to create a smooth surface.

Filling Small Cracks

For small cracks in plaster walls, you can use a plaster adhesive or a mixture of plaster of Paris and joint compound. Here’s how:

  1. Apply a thin layer of plaster adhesive along the crack using a putty knife.
  2. Press the adhesive into the crack and smooth it out with the knife.
  3. If using a plaster of Paris and joint compound mixture, follow the instructions on the packaging to prepare the mixture.
  4. Apply the mixture over the crack, making sure to fill it completely.
  5. Use the putty knife to scrape off any excess filler and create a smooth finish.

Repairing Larger Cracks

If you’re dealing with larger cracks in your plaster walls, you’ll need to use fiberglass mesh tape and joint compound. Here’s the step-by-step process:

  1. Cut a piece of fiberglass mesh tape slightly longer than the crack.
  2. Press the tape firmly onto the crack, ensuring it covers the entire length.
  3. Apply a thin layer of joint compound over the tape using a putty knife.
  4. Smooth out the compound and feather the edges to blend with the surrounding wall.
  5. Allow the compound to dry completely before proceeding to the next step.

Dealing with Structural Issues

If you notice severe or recurring cracks in your plaster walls, it’s crucial to address any underlying structural issues. In such cases, it’s recommended to consult a professional contractor or a structural engineer who can assess the situation and provide appropriate solutions.

Sanding and Smoothing the Surface

Once the repairs have dried, it’s time to sand and smooth the surface. Follow these steps:

  1. Use fine-grit sandpaper to gently sand the repaired areas until they are smooth and even with the surrounding wall.
  2. Wipe away any dust with a clean, damp cloth.

Priming and Painting

To ensure a seamless finish, prime and paint the repaired areas. Here’s what you need to do:

  1. Apply a coat of primer to the repaired areas and let it dry.
  2. Once the primer is dry, paint the patched areas to match the rest of the wall.
  3. Feather the paint into the surrounding wall for a smooth transition.

Tips for Preventing Future Cracks

To minimize the chances of cracks reappearing in your plaster walls, consider the following tips:

  • Ensure proper ventilation to control humidity levels in your home.
  • Avoid drastic temperature fluctuations by maintaining a consistent indoor climate.
  • Address any foundation or structural issues promptly to prevent further damage.
  • Apply a fresh coat of paint periodically to protect the plaster and provide additional strength.


Repairing cracks in plaster walls is a task that can be accomplished with the right tools and techniques. By following the step-by-step process outlined in this article, you can restore the beauty of your walls and prevent further damage. Remember to address underlying structural issues if necessary and take proactive measures to prevent future cracks.


FAQ 1: Can I repair plaster cracks myself, or should I hire a professional?

You can repair small to moderate cracks in plaster walls yourself using the methods described in this article. However, if the cracks are severe or recurring, it’s advisable to consult a professional contractor or a structural engineer for a thorough assessment and appropriate solutions.

FAQ 2: How long does it take to repair cracks in plaster walls?

The time required to repair cracks in plaster walls can vary depending on the size and severity of the cracks. Small cracks can be repaired in a few hours, while larger cracks may take a day or more due to drying and curing times. It’s important to allow sufficient time for each step of the repair process to ensure a lasting and durable result.

FAQ 3: Can I paint over repaired plaster cracks immediately?

No, it’s recommended to allow the repaired areas to dry completely before applying paint. This ensures proper adhesion and prevents any moisture from affecting the paint finish. Follow the drying time specified on the product packaging or consult the manufacturer’s instructions for the filler material used.

FAQ 4: How often do I need to repaint my plaster walls to prevent cracks?

Repainting your plaster walls every 5 to 7 years can help maintain their integrity and prevent cracks. Regular paint maintenance not only refreshes the appearance of your walls but also provides an additional layer of protection, reducing the chances of moisture penetration and subsequent cracking.

FAQ 5: Can I use spackling compound instead of joint compound for repairing plaster cracks?

Spackling compound is primarily designed for repairing small holes and imperfections in drywall rather than plaster walls. Joint compound, on the other hand, is more suitable for repairing and reinforcing cracks in plaster. It offers better adhesion and flexibility, making it the preferred choice for plaster wall repairs.

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