How to Patch Large Holes in Plaster Walls

Plaster and plasterboard are effective and affordable materials to finish your walls with; however, over time they wear and holes can appear for many reasons. As you hang new items on the walls, screws and nails can create small holes. Large holes are rarer but can still occur. If you’ve had electrical work that has left a gap for access or your wall has received impact, the plaster may have damage.

In most cases, you don’t need to worry about re-plastering the entire wall. Instead, most highly skilled plasters will be very familiar with repairing holes in plaster. The process requires a few steps and the technique takes a bit of getting used to. Here’s a step-by-step guide showing you how our plasterers patch large holes.

Different Types of Fillers

There are several types of fillers available for various applications. These fillers are designed to address different needs and surfaces. Some common types of fillers include:

• Multi-Purpose Filler: This versatile filler is suitable for both interior and exterior use. It can be used on various surfaces, including plaster, wood, and masonry. Multi-purpose fillers are often used for general repairs and hole-filling.
• Wood Filler: Specifically formulated for wood surfaces, this filler is used to repair holes, gaps, and imperfections in wooden furniture, doors, and trim. It can be stained or painted to match the wood’s finish.
• Ceiling Filler: Designed for ceiling repairs, this filler is formulated to minimise sagging or dripping during application. It’s used to fill cracks and imperfections in ceiling surfaces.
• Exterior Filler: For outdoor applications, especially on concrete or masonry surfaces, exterior fillers are used. These are often weather-resistant and can withstand exposure to the elements.
• Hairline Crack Filler: This type of filler is designed to address very fine cracks in walls and ceilings. It’s formulated to be easy to work with for small repairs.
• Deep Gap Filler: When you have deeper holes or gaps to fill, deep gap fillers are used. These are typically stronger and designed to handle larger repairs.
• Specialised Fillers: Some fillers are formulated for specific purposes, such as fire-resistant fillers, flexible fillers for areas with movement, or decorative fillers for creating textured finishes.
• Decorator’s Caulk: While not a traditional filler, decorator’s caulk is used to seal gaps between walls and trim or along the edges of ceilings. It’s also used to fill fine cracks before painting.

The choice of filler depends on the specific repair or project you’re working on and the type of surface you’re dealing with. Always follow the manufacturer’s instructions and recommendations for the best results.

How to Plaster a Hole in the Wall: The Patch Method

The first thing to understand is that large holes cannot simply be plastered over. Damaged plaster is too weak to support itself, especially over such a large area. If this approach is taken, the new plaster would cave in on itself. Instead, any large holes have to be patched.

The Patch Method involves creating a patch of fibreglass mesh and covering the hole with it. Then, new plaster is applied over the patch to fix the hole. If you have plaster cracks that need attention a different method is required.

The Tools For The Job

You will need a small collection of tools to fix holes. Readily available from most hardware shops and a staple for any plastering professional:

• Plaster
• Plastering Trowel
• Bucket 
• Water
• Taping Knife
• Fibreglass Mesh
• Stanley Knife
• Spray Water Bottle
• Sanding Pad and 120 Grit Sandpaper
• Sheets 
• Hammer
• Nails
• Timber (if your walls are plasterboard)

Protecting Yourself

Plaster is not toxic but this job can generate a lot of dust that can cause irritation and bodily harm. Wearing protective goggles to prevent dust from entering your eyes and a dust mask so you don’t inhale any particles is a must. 

The Patching Process

There is a six-step process to patch a large hole in the plaster:

1. Preparing The Space and The Wall

The repair job can get very messy, so removing all furniture and covering any remaining items with dust sheets is your first step. Additional sheets are needed to protect the flooring from damage and help speed up the clean-up at the end.

Then, the hole in the plaster needs to be cleaned and tidied. A rectangular shape needs to be cut around the existing hole, creating an easy shape to fill. Using a Stanley knife, a plaster will remove any jagged edge leaving a smooth edge to work with.

There may be wooden lath beams behind your plaster. If this structure is damaged, it will need repairing before the patching process is continued.

If your walls have plasterboard, they will have originally been installed with studs. The next step is for these studs to be located. A plasterer will tap the wall and listen for a duller sound. Once the locations have been marked around the hole, noggins are created to help secure the patch. The noggins, small pieces of wood, are nailed into position between the studs and the inside of the hole. 

2. Sizing A Fibreglass Patch

With the hole now prepared, it’s time for the hole to be measured and a fibreglass mesh cut to size. For particularly large holes, a strong metal mesh may be more appropriate. Your plasterer will know which is preferred from their experience.

3. Securing And Preparing The Mesh

Next, the mesh is nailed to the wall or the noggins that have been prepared. It is then misted with lukewarm water, ensuring it and the surrounding area are damp. Plaster adheres better to these surfaces, though it should not be dripping wet.

4. Applying The First Layer Of Plaster

It’s now time for the plaster. A professional will mix equal parts plaster and lukewarm water in a bucket. Patching plaster is ideal, but it is possible to use multi-finish plaster or all-purpose filler. This is stirred until it has a thick consistency reminiscent of chocolate spread or peanut butter.

This plaster is applied with a plastering trowel. Each plasterer will have established their own craft; however, often they will start spreading a small amount with an angled trowel, keeping the tool flat against the wall towards the end of each stroke. It is important for them to spread the plaster evenly. Starting around the edge with the existing plaster and moving inwards to cover the mesh properly. 

When the hole is covered, the plaster is levelled with a trowel. Any excess is scraped off before it is left for a few hours to dry. Just before it has set, a scarifier is used to scratch the surface, giving it a rough texture for the next layer to adhere to.

5. Applying The Second Layer

Now the first layer is completely set, your plasterer will mix up another batch of plaster for the second coat. As this layer is the top coat, a level finish is critical; a trick of the trade is to use a softer mix to allow the plaster to make it easier to manipulate the plaster evenly. When the coat is applied, a taping knife helps keep the finish flush with the wall.

6. Sanding Down To Finish

After the plaster is set, the next step is for a plasterer to sand it down with 120-grit sandpaper. This crucial step removes any high spots, making it flush with the wall. You can arrange for a thin layer of joint compound to be applied to create a fine finish or for the wall to be painted.

The initial preparation should make their clean-up easy and your space can return to normal.

How to Fill Hairline Plaster Cracks

Hairline cracks can emerge for various reasons, often due to natural settling. If you notice these small cracks, it’s usually not a major concern.

• Begin by cleaning the crack and removing loose debris.
• Utilise a filler designed for hairline cracks to fill the gap.
• Once the filler is dry, sand it down.
• Apply another thin layer, and let it dry before sanding again.
• Finish by applying a mist coat of paint to blend the repair with the wall seamlessly.

How to Fill Large Holes in Walls

For larger, more substantial wall holes, a specialised filler is required to prevent further issues.

• Clean the hole, ensuring all loose materials are removed.
• Use a flat-edged tool to push the filler into the hole, slightly overfilling it.
• Smooth the filler with a wet knife.
• Follow the drying instructions, typically 1-2 hours.
• Sand the filler down for a smooth finish.
• For very deep holes, apply filler in layers and allow each layer to dry before adding more.
• Apply a mist coat for a seamless paint blend.

Filling Ceiling Plaster Cracks

Ceilings can develop hairline cracks due to settling. Look for a non-sag or specialised ceiling filler.

• Protect your floor and furniture with a dust sheet.
• Clean the area around the crack and remove loose bits.
• Fill the crack, overfilling it slightly.
• Smooth with a wet knife.
• Allow it to dry.
• Lightly sand the surface to make the filler flush with the ceiling.
• Apply a mist coat for a seamless repair.

Filling Holes in Wood

You can use multi-purpose fillers for both walls and wood, but there are wood fillers available that ensure it flexes with the wood for a perfect finish.

• Fill the hole, ensuring it’s slightly raised above the surface.
• For through-holes, lay the wood flat during filling.
• Check for gaps after filling; top up if necessary.
• Smooth the filler with a wet knife.
• Allow it to dry.
• Sand the filler to make it flush with the wood’s surface.
• Apply varnish or stain as needed.

Filling Holes in Concrete Walls

For exterior, concrete wall repairs, use a water and frost-resistant filler.

• Ensure surfaces are clean, dry, and free of dust or grease.
• Press the filler firmly into the hole, slightly overfilling it.
• Smooth it with a wet knife before it dries.
• Allow 1-2 hours for the filler to dry.
• Apply additional layers if the hole is deeper than 20mm, waiting for each layer to dry before adding more.

Our Plastering Services

If your plaster is damaged and you have a large hole in need of repair, we can help you achieve a smooth finish.

At AB Drylining, we serve customers far and wide, from the South West, Bath, Bristol, and Swindon, as well as the surrounding areas. Our professionals have decades of experience providing affordable plastering solutions that help repair your home or commercial space.

For a high-quality finish at competitive prices, contact our team today. We’ll discuss your options and find the right package for you.

FAQ 

Can I fill holes with caulk?

Yes, you can fill small holes from screws or nails with decorators caulk, though this method is not recommended for holes larger than half a centimetre. Consider using plaster for these larger repairs.

How can I fill screw holes in plasterboard?

Firstly, remove any mess or debris around the hole with a knife or sandpaper. Then use a joint compound, all-purpose filler or decorator’s caulk to fill it. Finally, sand the area to give a level finish.

How can I fix a hole in the ceiling?

Fixing a hole in the ceiling is similar to fixing a hole in the wall. Small holes can be sanded and then filled, and then larger holes can be patched. 

How can I fix deep holes in plaster?

If the deep hole has a small surface area, remove any debris from inside and around the hole, fill it with powder filler, and then plaster over it. Sand the new layer to make it even.

If the deep hole has a large surface area, remove the debris, create a fibreglass patch, attach it over the hole and then plaster onto the patch.

Is it possible to apply plaster to cover up a hole in the wall?

Yes, you can use plaster to cover a hole in the wall.

Am I capable of plastering a hole by myself?

Yes, it is possible to plaster a hole by yourself with some basic skills and materials, although many play it safe and contact a professional plasterer.

What is the procedure for plastering a substantial hole in the wall?

The procedure for plastering a substantial hole in the wall typically involves cleaning the area, applying a patching compound or filler, smoothing it, and then applying a layer of plaster.

What should you use to fill holes before applying plaster?

Before applying plaster, it’s best to use a patching compound or multipurpose filler to fill holes.

What’s the method for filling a spacious, yet shallow hole in the wall?

To fill a spacious, shallow hole in the wall, clean the area, apply filler, and smooth it to match the wall’s surface.

What is the preferred material that painters employ to patch wall holes?

Painters often use multipurpose fillers or joint compounds to patch wall holes.

How should you go about filling a significant hole in your home?

To fill a significant hole in your home, clean the area, apply a patching compound or filler, let it dry, sand it smooth, and then apply paint or plaster for a finished look.