Sanding a wall: Practical tips, instructions, and examples
- Difficultymedium
- Cost< £ 10
- Duration< 1 h
Introduction
Wall sanding isn’t a vital process, but it’s highly recommended if you want to apply paint or wallpaper as evenly as possible across the surface. Sanding plaster walls is also a typical step during renovations and new builds. With the right tools and tricks, even inexperienced DIYers can achieve smooth wall finishes. This guide will show you the best way to sand walls.
- protective mask/respirator
- work clothes
- covering material
- pencil
- wallpaper brush
- sanding block or polishing felt
- No materials needed
How to sand a wall: Step-by-step instructions
In the example we’re about to show you, we sand and repaint a 5m x 2.5m living room front wall. We recommend using our 15 tips for painting walls guide to find more information and colour inspiration for your living room.
First things first, you must remove any old wallpaper that hasn’t been properly taken off and repair any deep holes and cracks in the plaster. If there are smaller scratches and bits of wallpaper left, you can remove these during the sanding process in preparation for painting.
Pay close attention to your work and always follow the relevant safety measures to protect yourself and those around you. For example, always wear a respirator mask to protect against the dust created by sanding. Read our DIY safety precautions guide for the most important safety tips.
You’ll find more helpful tips and answers in the “Tips & Planning” section of this guide. For now, though, let’s dive into the wall sanding process.
Preparing the room
Clear the room as much as possible and cover any remaining furniture with tarpaulins, sealing off any gaps in the sheets. Ensure there is enough ventilation but avoid wind and draughts to prevent dust blowing around.
Marking uneven areas
Use a torch or a line laser to find uneven surfaces on your wall. Hold the light close and to the side to reveal the shadows of any uneven spots. Alternatively, a line laser will become warped and bent if it runs over uneven areas – just remember to switch off the self-levelling function.
Finding a firm footing
To ensure you don’t accidentally tilt your sander or lose your footing due to an unstable standing position, only work with fixed steps or scaffolding (the latter of which is great for high ceilings). Stepladders and stools are best avoided. Wall sanding is a lot easier if you don’t have to lift your arms up high.
Sanding the wall
Once you’ve prepared your workspace, you can begin sanding your drywall or plaster walls. Make circular movements using the random orbit sander from the inner wall to the outer edges, making sure not to press too hard and as smoothly and evenly as possible. Keep the sander moving when in contact with the wall to prevent creating any new holes or unevenness in the plaster.
If you need to take a break or change your position, mark where you stopped with a pencil. When it’s time to sand the corners, you can do this easily with a multi-sander tool.
Removing dust and assessing your work
Once you’ve completely sanded down the plaster, remove all the dust from the wall with a clean wallpaper brush or a hoover. Check the surface again with a torch or line laser and add touch-ups where required. You can also finish off small areas with hand sanding accessories, such as a sanding block, sanding sponge, or polishing felt. After this, you’re done!
Are you familiar with the Bosch 18-Volt battery system? We supply a wide variety of tools for numerous applications that all share the same 18-volt battery pack. This means that when you’re finished with one tool, you can simply swap the battery into the next one, making your DIY life a lot easier!
Tips and planning for wall sanding
In this section, you’ll find important tips and FAQs about sanding walls.
When is it a good idea to sand a wall?
There are two main scenarios where sanding a wall is required: replacing the old wall façade during renovations or applying fresh plaster.
If you want to paint over old plaster or apply new wallpaper, you don’t always have to remove it completely. It’s easier to simply sand down the plaster if it still sticks well to the substrate behind. This involves smoothing the surface, removing wallpaper residue, and sometimes getting rid of traces of nicotine or tile adhesive. Sanding ceilings and walls may also be required if the freshly applied plaster is uneven or too rough.
Removing tile adhesive
What should I consider when sanding plaster?
Sanding is a technique that’s been around for centuries and has always been about simply removing material from a surface. However, it’s often a lot more complicated than it seems due to the many tools, methods, and abrasives available.
The sanding process always involves the sanding material (typically sandpaper or sanding mesh) and the way in which it is moved (either manually or mechanically). To ensure successful wall sanding, therefore, you must consider the materials and methods you use.
The sanding material that is most suitable for your requirements will depend on the surface you’re working with. Your wall could be covered with wooden panels, concrete, plaster, drywall, plasterboard, or latex paint – each would require a different method and tool. In this guide, we focus on sanding gypsum plaster.
Which tool is best for sanding walls?
You should always ensure you’re using the right tools for the job. There are three main things to consider when selecting your appliances:
1) What material am I sanding?
2) How large is the area that I’m sanding?
3) How much material am I removing?
Below, we’ve listed a few examples of what tools to use for different applications. These mainly apply to sanding plaster:
- If you just want to sand a small area of your wall, you can simply use hand appliances and accessories like a sanding block.
- Multi-sanders with the right attachments are ideal for working on different areas and corners. Some models even let you attach a sanding plate to them that allows you to work on slightly larger areas in a similar way to orbital sanders.
- If you want to sand an entire wall, random orbit sanders are your best option. The combination of oscillating and rotating movements from the sanding disc helps you achieve incredibly smooth finishes. A random orbit sander is also most suited to larger surfaces.
- If you’re working with a very large area of uneven wall that requires a lot of material removal, your best bet is a belt sander.
- Are you looking to sand concrete? You can achieve optimal results with an angle grinder and a suitable cup wheel.
- Specialised drywall sanders (sometimes called giraffe sanders because of their long necks) are also available to hire, but they are usually only worthwhile on very large areas.
Are there different levels of quality when sanding plaster?
Your desired end quality also plays an important role when sanding walls. There are quality levels ranging from Q1 to Q4 that serve as a guide for your sanding. You should aim for at least Q3 if you want to apply paint or wallpaper over your wall, whereas Q1 is sufficient if you want to re-tile your wall after sanding.
How important is the sandpaper grit type?
The key factor when choosing a sandpaper is the grit, which represents how fine the grains are. The grit size of sandpaper is marked by number and colour – the darker the paper, the coarser the grit. Examining the structure of sandpaper will make it clear how grit size effects the finish. The fewer abrasive grains there are per square centimetre, the rougher the material and end result.
Different grit sizes are usually labelled according to the Federation of European Producers of Abrasives (FEPA) with a letter P followed by a number. The higher the number, the finer the grit. Depending on the requirements, you may need a range of grit sizes for wall sanding.
| Grit Size | Applications |
|---|---|
| Fine grits, P220 and higher | Smooth finishes in gypsum plaster |
| Medium grits, P80 – P220 | Standard applications and most sanding work |
| Coarse grits, P80 and lower | Removing wallpaper and adhesive residue |
You can find even more tips and tricks in our handy guide to sanding. Although most of the information is related to sanding wood and metal, it’s also useful for wall sanding projects. The same goes for our video tutorial on metal grinding.
What safety precautions need to be considered when sanding walls?
As a result of the dust, you’ll always need to wear a respirator. If you’re sanding concrete with an angle grinder, you’ll also need to wear safety goggles to protect your eyes from flying pieces of concrete. Ear protection is also recommended.
You must also make sure you know the exact material you will be sanding before you start. After all, you don’t want to unexpectedly find hidden asbestos, which is still fairly common in old buildings.
Costs of wall sanding
Estimating the costs of wall sanding is no easy feat, as each project can be completely different. That said, you’ll certainly feel the cost savings if you sand down the plaster rather than have it replaced. Re-plastering quickly becomes more expensive than expected, largely due to underestimating the surface area.
For example, if a room has a floor area of 25 square metres and a ceiling height of 2.5 metres, you end up with 50 square metres of wall surface. Re-plastering this area to a quality level of Q3 costs at least £30 per square metre from a specialist, making the whole project total more than £1,500.
However, if you hire a contractor to sand the wall at an hourly rate of £40, you’ll save a lot more money. Assuming they take around 15 minutes per square metre, we can calculate the overall cost:
50 square metres x 15 minutes = 750 square metres per minute
750 square metres / 60 minutes = 12.5 hours
12.5 hours x £40 = £500
As you can see, this works out a lot cheaper. The table below shows a clearer comparison between the two processes:
| Re-plastering a wall | Sanding a wall down |
|---|---|
| 50m² of new plaster = £1,500 | 50m² of sanding = £500 |
| Cost per m² = £30 | Cost per m² = £10 |
It’s always cheaper to do any DIY projects yourself rather than hire someone in. Sanding a wall yourself will save you tons of money since sandpaper costs only a few pounds form any DIY store.