How to Plaster a Wall

Learning the full scope of plastering takes years of apprenticeship, but some useful skills can be picked up quickly. With practice, you’ll be surprised at how soon you can achieve professional results.

This DIY guide covers how to prepare for skim coat plastering. It includes instructions on fixing plasterboard to a stud wall or dot and dab over an existing surface, repairing plaster areas, laying on undercoat plaster, and applying the final skim coat.

What Jobs Can a Novice Plasterer Tackle Fairly Easily?

With some basic training, novice plasterers can confidently handle several tasks:

• Fixing Plasterboard: Attach plasterboard to a wood frame, stud wall, or ceiling using nails or screws. Learn more in our plasterboard project
• Dry Lining (Dot and Dab): Apply plasterboard to solid walls using plasterboard adhesive. Details are available in our dot and bad project guide
• Skimming Surfaces: Skim a plasterboard surface or re-skim an entire room, including the ceiling, to prepare for redecorating.
• Plaster Repairs: Repair plaster areas from bare brick with a patched skim finish

However, it’s crucial to understand the “feel” of plastering and how to control the surface you’re working on. Without proper training, you may end up with a finish that needs to be redone by a professional. The cost and time to fix mistakes often exceed the cost of attending a short plastering course.

Achieving a high-quality finish requires managing tools and materials in response to the changing conditions of the plaster. This skill largely comes from experience gained over years of work.

The Main Steps of the Plastering Process

To ensure that any plastering job is successful there are certain steps that need to be completed in a certain order to ensure that once the plaster is laid on the wall it stays there for many years to come, there is a certain set process that needs to be followed closely. These main steps are as follows:

1. Prepare Walls: Remove any loose items, dust and debris from the walls surface. If plaster boarding or dot and dab, fix plasterboard to walls and then apply skim tape over all joints
2. Prime and Seal Wall: To give a stable base when laying skim plaster on to older base coat plaster and slow the absorption rate, especially if you are a novice plasterer, its a good idea to coat the wall in 2 coats of a 50/50 PVA and water mix. Allow to dry for 24 hours
3. Prepare Work Area: Clear the work area of any unnecessary obstructions and lay out all the kit you need, including all tools, materials, clean water etc. Have everything you need to hand
4. Damp Down Wall: If you aren’t sealing the wall with a 50/50 PVA mix, or are laying on a base coat directly on bare masonry, using a masonry paint brush, brush clean water over the entire wall to dampen it and slow the absorption rate of any new plaster that is applied
5. Mix up Plaster: Mix up your desired plater to the right consistency so that it is self-supporting ready for laying on
6. Lay on Base Coat/Scratch Coat: Lay on the base or scratach coat of plaster over walls surface to a uniform thickness, should be around 10mm for base/scratch coat plaster, but will depend on the thickness you have to work with
7. Lay on First Coat: Once base coat has cured, lay on the first layer of skim coat of plaster to around 3mm thick
8. Lay on Second Coat: As soon as the first coat is on the wall, lay on the second coat straight away, again should be around 3mm thick
9. Smooth Over: Once the second coat is on the wall and has started to harden, use trowel to smooth out all lines and imperfections to leave a smooth, finished covering over the walls surface
10. Finish up: Once all smoothed and finished, quickly clean up all tools and any objects used before plaster sets on then

It is essential that each step is followed correctly and in order as if anything is skipped then this can potentially compromise the overall outcome and success of your plastering work.

What is Plasterboard?

Plasterboard is a versatile material used to prepare solid and stud walls for skimming quickly and cost-effectively. It allows DIY enthusiasts to plaster new walls or make existing ones square and plumb for re-plastering or tiling.

Plasterboard comes in various sizes and thicknesses to suit different tasks, with specific types designed for particular applications:

• Standard Plasterboard: Typically 9.5mm or 12.5mm thick, available in various sizes
• Fire Lining Plasterboard: Increases the fire resistance of a wall
• Moisture Barrier Board: Ideal for areas like bay windows where warm, moist air meets cold surfaces, causing condensation.
• "Aqua" Board: Used in wet areas such as showers and bathrooms.
• Sound and Thermal Insulation Boards: Help meet local building regulations for noise and heat insulation.

Always consult with your builder’s merchant to ensure you purchase the correct type of plasterboard for your project.

Plasterboard is typically cut to size before fixing. When applying plasterboard to a stud wall, cut it to fit the center of the joist or noggin. For solid walls, cut the plasterboard to maximize the use of the board, ensuring minimal waste.

Cutting Plasterboard to Size

To cut plasterboard, you need a retractable knife, straight edge, tape measure, pad saw, rasp, and pencil.

1. Measure and Mark: Measure the required dimensions and mark them on the plasterboard. Remember to “measure twice, cut once”.
2. Cutting the Board: For a straight cut, run the knife along the marked line using a straight edge as a guide. Cut through one side of the paper. Apply pressure to the opposite side of the cut line to snap the board cleanly. Finish by cutting through the remaining paper layer.
3. Tidy the Cut: Use the rasp to smooth and shape the edges as needed.
4. Cutting Recesses: For recesses, like around a window corner, use a pad saw to make the initial cut. Then, use the retractable knife and straight edge to finish the cut from the board’s edge to the pad saw cut

By following these steps, you can achieve precise cuts and clean edges on your plasterboard, ensuring a professional finish for your project.

Fixing Plasterboard

To fix plasterboard to a stud wall, use galvanised clout nails or drywall screws. For solid walls, apply plasterboard using adhesive with the dot and dab method. Learn more about fixing plasterboard in our detailed guide.

When attaching plasterboard to a ceiling, use a “third arm” or “dead man” tool to hold the board in place while you secure it to the ceiling joists. This method ensures a secure and efficient installation.

What is Dot and Dab?

Dot and dab is a popular method for attaching plasterboard to walls, aside from using studs. Here’s a simple guide to get you started:

1. Prepare the Wall and Board: Cut the plasterboard to the desired size.
2. Apply Adhesive: Apply dots of plasterboard adhesive to the wall surface.
3. Attach the Plasterboard: Push the plasterboard onto the adhesive dots. Ensure the edges, especially where the skirting board will be fixed, are well supported.
4. Align the Board: Use a straight edge and a level to ensure the plasterboard is vertical and straight. Gently tap with the straight edge to adjust.
5. Check Horizontal Alignment: Make sure the board is not slanting inward or outward on the horizontal plane.
6. Repeat for Additional Boards: Apply subsequent boards using the same method, ensuring they are “true” and “plumb” relative to each other. Use a straight edge across multiple boards to avoid undulating surfaces and steps between boards, which can complicate skimming.

For a more detailed guide, visit our dot and dab plastering project.

Dry Lining vs Dot and Dab: Which One to Use?

When it comes to wall construction and finishing, two popular methods are dry lining and dot and dab. Understanding the differences, advantages, and disadvantages of each can help you choose the best technique for your project.

Dry Lining

The main advantages of dry lining are as follows:

• It’s versatile and can be used over any walls surface, even very uneven ones
• The voids between studs can be filled with insulation
• The framework allows for easy installation of cables and pipework
• Once constructed, stud frames are extremely sturdy and solid

On the flip side, the main disadvantages are:

• Stud frames can be bulky and will take a up quite a bit of space, decreasing room size
• Erecting a stud frame can be quite an involved job and generally, slower than applying dot and dab
• Timber can be expensive and due to this, dry lining is generally more expensive than dot and dab

Dot and Dab

To balance the argument for dot and dab, it’s main advantages of dot and dab are:

• Dot and dab is quick to fix to ay surface
• It’s also very cost-effective, requiring few materials
• Unlike stud framework, it takes up relatively little space
• It’s very easy to master as a technique

And to finalise, the main downsides to dot and dab are:

• The slight gap behind doesn’t allow for insulation
• Only generally good on fairly flat surfaces, doesn’t fair well on uneven surfaces
• Can be tricky to run cables and pipework behind

The choice between dry lining and dot and dab depends on your specific needs and project conditions. For new constructions or major renovations where insulation and wiring flexibility are priorities, dry lining is often the preferred method. However, for quick renovations, budget constraints, or when working with reasonably flat surfaces, dot and dab offers an efficient and economical solution.

By understanding the pros and cons of each method, you can make an informed decision that best suits your project’s requirements. Whether you prioritize insulation, speed, or cost, knowing the differences between dry lining and dot and dab will ensure you achieve the best results for your walls.

Skimming and Over Skimming: What’s the Difference?

Skimming involves applying a thin, smooth plaster coat over an undercoat plaster, creating a flat and level surface. This technique is used to achieve a polished finish on newly plastered walls.

Over Skimming is applying a final skim coat over an existing plastered surface. This is useful for fixing damaged, chipped, or uneven walls. It provides a fresh, smooth layer without the need for extensive repairs.

For novice plasterers, we recommend using Multi Finish plaster. While Board Finish is designed for plasterboard surfaces, it sets too quickly for beginners to manage effectively.

Calculating the Amount of Plaster You Need

To determine how much plaster to buy, consider the following:

1. For a 12mm thick coat (about ½ inch), a 25kg bag of browning, bonding, or one-coat plaster will cover approximately 3 square meters.
2. For top coat or skim plaster at 3mm thick, a 25kg bag will cover about 13 square meters.

Only buy what you need and use it promptly, as plaster has a short shelf life and cannot be used once it’s out of date!

Tips to Consider Before Starting Plastering

Plastering is a challenging skill that requires significant training to achieve a smooth, flat surface. While books and guides can teach you the basics, practice is essential for mastering the craft.

Plastering involves timing and “feel”. A wall may look flat, but an experienced plasterer can identify and correct imperfections by running a trowel over it. Just like electrical or plumbing work, improper plastering can be costly to fix.

To get started, consider enrolling in a reputable plastering course to learn the basics. For those wanting to try plastering themselves, here are some key tips:

1. Practice First: Before tackling your main project, practice on an old wall or a sheet of hardboard. Coat the hardboard with undiluted PVA adhesive and let it dry for 10 minutes. This will give you a suitable surface to practice spreading plaster and transferring it from the hawk to the board.
2. Understand the Timing: Plaster sets quickly, so you must work efficiently to smooth it out before it hardens.
3. Get the Right Tools: Ensure you have the necessary tools, such as a trowel, hawk, and plaster mix, to make the job easier and more efficient.

For more detailed steps and tips, consider reading up on plastering techniques and watching some of the many helpful videos found online to complement your practice.

Tools Required For Plastering

Here follows a list of the common tools and materials that are used when plastering:

• Flexible bucket
• Bucket trowel
• Paddel mixer
• Spot board
• Hand board
• Finishing trowel
• 2 buckets clean water – 1 for mixing 1 for cleaning tools
• 1” and 4” clean paint brush
• Scraper
• The correct type of plaster for the job you are doing
• Spray bottle/rose sprayer
• Plasterers hawk
• PVA adhesive – for sealing wall if needed
• Stiff brush

How to Plaster a Wall

As we have now explored the various different types of plastering, types of wall and the tools and products needed to cover such surfaces, it’s now time to start looking at how to get plaster actually on the wall.

Step 1 – Prepare Walls Surface

Proper wall preparation is crucial for successful plastering. If starting from scratch, this includes building your studwork wall or using the dot and dab method to create a stable surface.

For an existing flat masonry wall, clean it thoroughly, removing dust, debris, and any loose materials.

When working with plasterboard, apply scrim tape to all the joints and nail/screw heads to ensure a smooth finish and prevent the joints cracking once plastered over.

Step 2 – Prime and Seal Wall

If you are working with an already base coat plastered surface and that base coat has been on the wall for some time it’s a great idea to give it a good coating of PVA mixed to a ratio of 50/50 with clean water.

Once mixed, paint the solution on the surface and allow to dry and then repeat for a second coat. Once this has dried (leave for 24 hours ideally), this will provide a stable base that will reduce absorption and increase drying time for your new plaster, ideal also if you are a plastering novice.

Step 3 – Clear and Prepare Work Area

Before laying any plaster on any surface, it’s essential that you clear and prepare your work area.

Plastering is a messy job so clear any movable objects away and cover any fixed surfaces or items with dust sheets, ideally plastic ones. Also cover all floor surfaces.

Next, move all of your tools and equipment to or as close to your work area as possible. Due to the mess, any mixing should really be done outside or in a garage or similar covered area, but stay as close to the working area as you can. Plaster gets heavier the longer the day goes on!

Step 4 – Dampen Down Walls

Masonry surfaces are extremely porous and will easily suck much of the moisture out of fresh plaster affecting how well it bonds to a walls surface. To slow this process down, use a masonry paint brush to brush clean water over any bare masonry surfaces, this will drastically slow the rate at which any moisture from the plaster is absorbed by the surface it’s laid on to.

This is also the case for any of your tools, spot boards, trowels, hawks and the likes, make sure they are all nice and damp!

Step 5 – Prepare Plaster Mix

Mix the plaster to a smooth, creamy consistency, ensuring all lumps are removed and any dry patches around the mixing bucket are incorporated.

As a general guideline, aim for a consistency similar to thick porridge that supports itself. When piled on the spot board, it should stay in place and only move if the board is lightly tapped with a trowel or similar tool.

Before pouring out the plaster onto the spot board, pre-wet the board.

Step 6 – Prepare Plaster for Application

Wet your hand board and trowel. Prime the hand board with a small amount of plaster, then load the plaster onto the hand board or hawk. To transfer the plaster from the hand board to the trowel, pass the trowel over the plaster on the hand board and “squeeze” the plaster onto the trowel, creating a sharp wedge of plaster on the edge of the trowel.

Step 7 – Apply First Coat of Plaster

Divide your wall or ceiling into three horizontal sections. Start plastering at the top left of the top section, moving across to the bottom right. Apply an even coat of plaster about 3mm deep.

Once the top section is covered, repeat the process on the middle third, then on the bottom third. This “pattern of three” method helps both novices and experienced plasterers maintain control and predict how the plaster will dry.

Briefly smooth the first coat to sharpen edges and corners using a wet small brush or the edge of the trowel. Focus on removing obvious high spots. Then, smooth the wall to a relatively even finish, filling any holes and moving high spots into low spots.

Don’t dwell too long on this smoothing, it should only be very quick as you need to lay your second coat on pretty much straight away and the process of laying this on will deal with most troublesome areas.

Step 8 – Apply Second Plaster Coat

Quickly prepare a second mix of Multi Finish plaster to a lump-free consistency similar to thick porridge. Apply this coat, known as the laying down coat, over the first coat without delay.

Follow the “pattern of three” method again, aiming for a smoother finish this time. Work efficiently to cover the entire wall before the plaster hardens too much.

Remember, plaster remains workable for only 10 to 20 minutes once mixed and this time will change depending on the temperature e.g. even quicker if it’s warmer.

Step 9 – Initial Trowelling

After covering the wall, perform the first trowelling pass to smooth it out. Utilize the “pattern of three” method, avoiding focusing on one spot.

Ensure any holes are filled and lines are flattened, moving towards the desired final finish. This step is crucial for achieving a smooth surface, addressing large lines, holes and other imperfections that will spoil the overall finish.

Step 10 – Final Trowelling

You’ll now trowel the wall in three sets of three trowels.

1. First Set: When the wall is firming up, trowel with single strokes three times. To test, press your thumb gently into a out-of-sight area, it should only leave a very slight indent and thumb print
2. Second Set: Up to 15 minutes later, use a moist 4″ paint brush ahead of the trowel to lubricate the plaster.
3. Final Set: Up to 40 minutes later, when the wall feels set, repeat the technique from the second set for a final finish.

This method maintains consistency, prevents over-troweling, and ensures a smooth, dull finish. Once flat and smooth, your job is complete. Well done!

Other Types of Plastering

The plastering process details above describes the process of plastering from scratch e.g. starting with a bare masonry or plaster board surface. However there are scenarios where this may not necessarily be the case:

Over Skim Plastering

The process of over skimming a wall mirrors that of plastering a plasterboard wall. However, before applying the new top coat, it’s crucial to seal the wall with diluted PVA glue to prevent it from absorbing moisture too quickly.

Steps:

1. Dilute PVA glue (5 parts water to 1 part glue) and apply up to two coats using the “pattern of three” brush technique. This seals the wall, slowing the rate at which the old plaster absorbs moisture from the new plaster and extends your working time.
2. Ensure any loose plaster is removed and repaired before proceeding with the skim coat.

Note: Feathering in the plaster up to window beads may be necessary, or you can opt to apply new beads using plasterboard adhesive or bonding.

Patch Repairing Plaster

When a patch of plaster comes off a wall, you can repair it before skimming with Bonding Compound. Here’s how:

Step 1 – Apply Bonding Compound

1. Divide the repair area into two horizontal parts.
2. Start at the top right and plaster across the top half, building up coats of no more than 15mm thickness
3. Repeat the process for the bottom half, ensuring the top half is slightly proud of the repair area.

Step 2 – Level and Refill

1. Use a plasterer’s darby to level the patch, bridging it across the old plaster.
2. Spread and grade the plaster with the darby, completing the final coat for the bottom half of the repair.

Step 3 – Final Touches

1. Give the bonding one trowel to smooth; excessive smoothing can cause blistering during skimming.
2. Once dry, skim the wall as usual. If feathering in a patch repair, leave the bonding slightly shallow compared to the surrounding plaster and fill the rest with skim.

Laying on Undercoat Plaster

The process of applying undercoat plaster, known as “laying on”, provides a base for the finish plaster coat. Here’s what you need and how to do it:

This stage also commonly uses angle beads where required, to create nice, crisp coners. MOre information on this can be seen in our project on base coat plastering.

You will need the following tools and products:

• a bucket of water
• a large emulsion brush
• undercoat plaster mix (see Chapter 9 for details on mixing the plaster)
• a hawk
• a bucket trowel
• a steel trowel/float
• a straight-edged length of metal 1.5m long
• a plastic float
• a small tool for filling narrow gaps (see figure 9.1)
• a nail or a small screwdriver to ‘scratch’ the plaster.

Before starting, dampen the wall with water using the emulsion brush. Ensure it’s only damp, not dripping wet.

Applying Undercoat Plaster

To apply undercoat plaster:

• Prepare Plaster: Place two trowel loads of mixed plaster on your hawk.
• Apply to Wall: Scoop plaster from the hawk onto the steel trowel and spread it onto the wall, slightly above the beads.
• Smooth with Straight Edge: Use a metal straight edge over the bottom beads of the filled section, pulling upwards to smooth the plaster.
• Refill and Smooth: Scrape excess plaster, refill holes, and smooth the surface until it’s full, flat, and relatively smooth.
• Repeat Process: Move to the next section and repeat until the plaster starts to harden.
• Rub In: Once the surface is firm enough, use a plastic float in a circular motion to close any remaining fissures and smooth the surface.
• Check and Correct: Feel the surface for depressions or high spots and adjust the plaster accordingly.
• Fill Narrow Gaps: Use a small tool to fill narrow areas like doorframe gaps.
• Scratch Coat: After a couple of hours, scratch the plaster with a nail or screwdriver in a coil shape, ensuring coverage with no more than 150mm between scratches.
• Smooth Out Scratches: Lightly rub the wall with a plastic float to flatten any burrs caused by scratching.
• Ready for Top Coat: Your wall is now prepared for the top coat application.

Creating a Scratch Coat

For scratching the coat, special metal combs are generally used, but they are optional, you can make your own by knocking some thin nails through a piece of timber, so they protrude about an inch through the bottom.

Aim to scratch no more than 4m² at a time. After scratching, lightly rub the wall again with a plastic float to flatten any burrs. Now, your wall is ready for the top coat application.

Plastering is a skilled job and cannot be learnt exclusively form a book or a video. In order to master it you need to physically practice and do it and develop a feel for laying it on and smoothing it off. Once you have done so, you will then be plastering away like the pros!