The Essential Step by Step Guide to Lath and Plaster Repair

February 25, 2021

Before you embark on a big DIY project, it’s important to do your research. This is especially true when it comes to home repairs for lath and plaster. Making a mistake could be costly, so it’s best to understand what you need to do even before you start! 

If you are tackling a project with your walls, you may need to learn about lath and plaster. This is a popular way to cover walls in homes both new and old. You’ll first need to develop your technique to do it properly. Read on to find out exactly what you need to know to get started. 

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Lath and plaster

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What is Lath and Plaster?

Lath and plaster is a process used to finish interior walls and ceiling. Lath is the name for the narrow boards of varying widths that are fixed to the timbers inside your walls. This creates a horizontal working surface that allows the plaster to bind to it to give your walls a lasting surface.
Plaster is a mixture of gypsum cements that, when mixed with water, creates a putty-like substance that can be smoothed onto your walls. When it dries, it creates a hard, solid surface. It usually requires several coats to build up the walls to the proper thickness.

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How Does Lath and Plaster Compare to Regular Plaster?

It takes a bit more time to complete plastering this way, but it is well worth it. Lath and plaster is very durable, meaning it is still a popular building procedure today. It will last for decades! Thicker than plasterboard, it requires more plaster but is better at absorbing sound. It’s also more fire resistance, working to keep you safe.
Your home’s features may include unusual layouts where plasterboard doesn’t work. For example, a lath and plaster ceiling will allow you to accommodate a curved or sloped surface, offering you more flexibility in how your home looks.

How Thick is a Lath and Plaster Wall?

You might also need to know how thick a typical lath and plaster wall is. This way, you can use this information to check on your own work to be sure that it’s up to par. Your wall’s width is determined by a few different factors. Most walls use timbers of 100 mm thickness. Then, you’ll need to consider the thickness of both lath and plaster for the final calculation.
Lath may vary slightly in width, but averages about 6mm. Several coats of plaster build up your wall. These coats will typically account for 20-22 mm. When it’s all said and done, the combination will give you a thickness of about 26 to 30 mm! An interior wall finished on both sides, will be around 150 mm. When it’s done correctly, it will be built to last. This information can also help you plan your repairs for a wall that fits the space of your home.

How to Repair Lath and Plaster Walls Step By Step


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Do you see cracks or crumbling plaster on your walls? Can you feel bumps or bulges on the surface? Or is it a problem with the ceiling? Any of these sights will point to a problem. It’s a sure sign that your walls need repair, but you may not know where to start.
You’ll want to research the techniques for lath and plaster removal before you get started so you can proceed with an informed, skilled repair. Read on to find out what you’ll need to know before you begin your repairs. Or consider bringing in a contractor to help you with your walls to be sure your repairs are done properly.

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You’ll need the right tools to get started. Here’s a rough outline of what should be on hand.

  • Knife for removing the damaged plaster
  • Plaster to mix up for the repair
  • Putty knives to apply the plaster smoothly and evenly
  • Sandpaper to smooth out your work and allowing you to build up your coats


To get ready for the job, locate and mark all of the areas that need repair. This will make it easier to move between them once you have the plastering ready.
Remove any visible damage, including loose plaster. Be careful when cutting out the damaged or crumbling plaster so you don’t disturb the lath beneath. You may need to excise all of your layers of plaster in order to start fresh.
If your lath requires repair, remove the plaster surrounding the damage to give you a clear area to work. You’ll need to handle your repairs from the inside out to be sure you have a wall that will last. Once the plaster is gone, you can examine whether you need to re-fasten the lath or replace it.

Step by Step Guide

Prepare your surface for plastering. This is where your preparation comes in handy. All damage should be removed.

  1. Make sure to remove any dust from the area to be plastered so your new plaster will adhere and be strong. Tip: A raw, unfinished surface for the best results. Avoid applying plaster to a painted or finished area.
  2. Apply a coat of plaster to the area. Depending on the damage you’re repairing, this could be a thin topcoat or a thicker base layer. Remember that it’s best to build up your coats.
  3. Let it dry thoroughly.
  4. Sand the coat to ensure your next will stick. This also allows you to make sure the coat is even so your wall will stay even.
  5. Repeat steps 2-4 as required to get your wall to the proper thickness, matching the rest of your wall. Your repair should be seamless to the eye and to the touch.
  6. Once your plaster is dry, you can think about finishing steps to make it blend in with the rest of your wall. Allow several days for the plaster to cure correctly.

How to Remove Lath and Plaster

If your walls are beyond a simple repair, don’t fret! You just need to remove the troublesome lath and plaster and replace it so your walls are beautiful again. It can be time consuming and messy, so keep this in mind before you start. Here are a few of the main steps you’ll need to know to remove existing lath and plaster.

lath and plaster

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  1. Keep working on your walls to remove all of the plaster. It won’t come away easily, so you’ll need to keep at it with your hammer until you see plaster coming down. Apply the elbow grease and prepare for a tough job.
  2. Lay down plastic and seal up the area you’ll be working in. This will help to keep the dust and mess contained.
  3. Using a hammer, tap at the plaster until it loosens and you can see the lath beneath. Once you have a hole revealed, use the claw of your hammer to loosen more plaster from your wall.
  4. Keep an eye on the mess and clean as you go to reduce the time you spend cleaning up. Continue until all of the plaster is removed from your desired area.
  5. Once the plaster is free from your walls, you can start to remove your lath. Locate an area where the ends of the lath have been nailed to your timbers.
  6. Use a crowbar or the end of your hammer to loosen this end to pull the strip away from the timber. You’ll need to remove all of the nails holding it firm.
  7. Tip: Loosen the ends of several boards, then move along the wall to loosen them at each connection. This way, you move less and get more boards off at once!

What is The Best Way to Hang Pictures on Lath and Plaster Walls?

After you’ve finished repairing your lath and plaster and painted, your new walls deserve a few finishing touches. But before you pick up your hammer and nails, read through these tips to decorate your new walls with pictures the right way!

hanging pictures on a plaster wall

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  • Use the proper tools. Since plaster is very hard, just tapping a nail in could crack your new walls. Even worse, it could separate your plaster from the lath behind! To avoid catastrophe, we recommend pre-drilling the hole first. Then you can hammer in the nail to hang your picture without fear.
  • Use a level to ensure your pictures are straight and even.
  • Plan out your decorations on the floor to figure out the arrangement first, that way you’ll just hang it once without adjustments!
  • For heavy decorations, like mirrors or large pictures, locate a stud first. Then, use this to anchor your nails and the weight of the decorations.
  • Be creative and add a picture rail! This is a strip of wooden moulding that runs horizontally along the border of your room. Thanks to its design, it’s easy to attach fasteners. This makes hanging and changing your pictures easy, without ever worrying about damaging your plaster.


Now that you’ve learned more about lath and plaster, turn your attention to your own home. Do you see any signs of damage that need tending? It does happen, no matter how careful you are! As a traditional building method, lath and plaster is a durable covering for any of the walls or ceilings inside your home. But time can take a toll on your walls so they require some care.
If it’s time to repair, you’ll want to make sure the work is done properly so you can enjoy your home for years to come. Repairing lath and plaster requires knowledge, preparation, and some skill. Pick up the right tools and take it slow to build up your confidence. Not sure you’re ready to tackle the work, or worried about the mess? Hiring a professional plasterer to handle the project will guarantee it gets done right.

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