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How to fix cracks in plaster

Most homeowners will have experienced cracks in their plaster walls or ceilings at least once and it can be hard not to panic. Seeing a long crack in the wall of your new home can be worrying, but how do you know if a wall crack is serious?

Read on to find out how to fix cracks in plaster, how to fix cracks in corners, fixing recurring cracks and what the best filler for cracks in plaster is.

How to fix cracks in plaster

Plaster creates smooth, strong walls that last for years and years.

Unfortunately, over time, it can be prone to cracks that can sometimes be an indicator of a more serious issue. Learning how to fix cracks in plaster is a great skill to have.

One of the best ways to fix cracks in plaster walls is to start by scoring the crack. This will help to remove any loose plaster and create a larger surface for the joint compound to adhere to.

To begin with, you will need a range of tools and materials including:

  • Stanley knife
  • Chisel
  • Filler knife
  • Drywall tape
  • Tray for mixing joint compound if necessary
  • Drywall joint compound
  • Sandpaper
  • Scissors
  • Vacuum cleaner

Top tip: Skip ahead to our ‘cracks in plaster, when to worry’ section if you’re concerned about your wall or ceiling crack before continuing.

For best results, we always recommend hiring a professional. If the crack is larger than 0.5cm we recommend getting in touch with a structural engineer.

how to repair deep cracks in plaster walls

How to fix cracks in plaster walls

Once you’ve gathered your tools, make sure you cover any surfaces and move any furniture out of the way.

You may need to stand on a step ladder, especially if the crack is located on your ceiling. Then, use the following steps for quick results:

  1. Start by scoring the crack using your Stanley knife. Carefully remove any loose plaster and widen the crack
  2. Vacuum the crack to get rid of any small pieces of plaster and dust
  3. Next, cut a piece of drywall tape the length of the crack using scissors and set aside
  4. Using your tray, mix the joint compound as directed by the packaging
  5. Then, add a small amount of the mixture to your drywall knife and spread over the crack. Ensure you add a thin layer that covers either side of the crack
  6. You can then take your piece of drywall tape and position it, covering the crack. Smooth out any bumps with your drywall knife but be careful not to rip the tape
  7. Smooth another layer of joint compound over the crack with your drywall knife and allow to dry
  8. Finally, sand the area until it’s flat and even but be careful not to sand down to the tape

Top tip: This method also works well if you’re wondering how to fix hairline cracks in plaster walls.

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How to find a good plasterer

How to fix cracks in corners of plaster walls

Sometimes cracks appear in difficult to reach areas like corners. The best solution is to follow a similar method to that described in the previous section.

The main difference is that you apply more than one piece of drywall tape, covering each side of the crack. You can then lightly cover the tape with joint compound, let it set, and then sand as usual.

How to fix recurring cracks in plaster

Frustratingly, even after you fix a crack in your ceiling or wall, it can reappear over time. This is usually caused by a shift in your home’s foundations which is often nothing to worry about.

If your recurring cracks are more serious, we highly recommend contacting a professional.

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How to fix cracks in plaster walls before painting

Not all cracks in plaster are the same and it may be useful to know how to handle these before they become an issue. Two different types of cracks are:

  1. Peeling plaster cracks: If plaster starts to peel away from your ceiling in large patches, it’s time to speak to an structural engineer
  2. Shrinkage cracks: These cracks branch out and spread over an area of your wall or ceiling. Minor shrinkage cracks can be repaired by filling them with plaster

You must fix any cracks in your plaster sooner rather than later to prevent the issue from worsening. If you don’t address these problems before decorating, you won’t achieve a flawless, even finish and the cracks will simply reappear.

For most minor cracks, follow our method above. For more serious cracks, get in touch with a professional as soon as possible.

Don’t fancy decorating yourself? For best results, we recommend hiring a professional painter and decorator.

Treating damp mould on internal walls

Damp and mould can quickly spread over your walls, floors and ceilings. They can even affect your furniture and possessions if they come into contact with them.

Damp and mould can also cause health issues, so it’s really important to treat it as soon as you spot it.

To guide you through the process of tackling damp and mould, take a look at our guide to getting rid of black mould, condensation and damp.

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What is the best filler for cracks in plaster?

Filling cracks in your ceilings and walls is important to keep your home looking great and prevent future issues. Make sure you go for a filler that is hard-wearing and can be sanded down.

How do you repair deep cracks in UK plaster walls?

When it comes to deep cracks, it’s difficult not to worry about any further implications regarding the structural integrity of your home. You can repair these cracks yourself, but for peace of mind, we recommend hiring an expert to deal with them.

If you’d like to try yourself, follow these steps:

  • Use a chisel or knife to carefully remove any debris or lumps of plaster from the deep crack
  • Fill with newspaper before applying plaster of Paris to add extra stability to the crack
  • Apply a layer of plaster over the newspaper covering the crack
  • Once that plaster is dry, add another layer and repeat until the wall or ceiling and the crack are level
  • Finally, use sandpaper to smooth over the area

Which trade should you use for the job?

The best tradesperson for your job will depend on the extent of the crack. Small, minor cracks can be easily dealt with by a plasterer or general builder, but serious cracks need to be assessed by a structural engineer.

To make your room ‘good’ again, hire a painter and decorator to give it a new lease of life.

Are cracks in plaster walls normal?

Absolutely, cracks in plaster walls are a normal part of owning a home and usually nothing to be concerned about. Many new houses are prone to cracks while the house settles over time.

Of course, there are instances when cracks are more serious and the tips in our ‘cracks in plaster, when to worry’ section should help you to know whether or not to contact an expert.

When should I worry about cracks in plaster?

Cracks come in all shapes and sizes, some deep and some shallow but how do you know if a wall crack is serious?

Generally, cracks in plaster are very common and usually nothing to be concerned about, but there are instances when a crack could indicate a deeper issue. If you’re wondering when to worry about cracks in plaster, use the following guidelines:

  • Width of crack: If your crack is wider than 0.5cm, it’s worth investigating. Once a crack reaches 2.5cm width this could mean your home has structural damage that needs to be quickly dealt with
  • Cracks over door frames: This could be a sign that your home’s foundations are damaged or moving so you should call an expert to assess the problem
  • Diagonal cracks: Any crack that runs diagonally or takes the shape of the bricks on the outside of your home needs to be looked at by a professional as your home’s foundations may be shifting

How much does plaster cost to be repaired?

The average cost to repair a small crack will be around £200.

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