How to finish a plasterboard wall with joint tape and filler: step by step

A new plasterboard wall is only ready for paint when the seams and screw holes are invisible. That takes patience and the right order: first joint tape, then filler in thin layers, then sanding. In this blog you will read step by step how to do that as a DIYer and what to watch for.

⚠️ Filler and sanding dust are irritating. Work with a dust mask, safety glasses and gloves. Do you want a perfectly smooth wall, or is the area large? Leave that to a plasterer or painter. Calling in a professional is never superfluous.

What do you need?

Materials

• Speedline paper joint tape or Speedline fibreglass joint tape for the seams and Speedline light filler for filling.
• A deep-penetrating primer to prepare the wall for paint.
• masking film to protect the floor and belongings.

Tools

• A putty knife with aluminium blade and an 12-litre bucket with clean water.
• sanding block grit 120 and sanding block grit 220 for coarse and fine sanding.
• A construction vacuum cleaner to remove dust straight away and a folding ladder with handle for higher seams.

Personal protective equipment

• work gloves with nitrile coating, safety goggles and a FFP2 dust mask against sanding dust.

Preparation

Check that the boards are firmly fixed and the screw heads sit slightly below the surface. Dust off the seams, cover the floor and frames and make sure there is good light, so you can see unevenness. Read the instructions of the tape and filler manufacturer for drying times and method.

Step by step: how to finish plasterboard

1. Fill the seams and screw holes thinly with filler and press the joint tape into it.
2. Smooth the tape and remove excess filler.
3. Let the first layer dry completely according to the manufacturer.
4. Apply a second, wider layer and pull it flat.
5. Let it dry again and sand first with grit 120 and then with grit 220.
6. Vacuum the wall and wipe it with a slightly damp cloth.
7. Apply the primer before you start painting.

💡 While sanding, hold a lamp at an angle against the wall. Then you see dents and edges you would otherwise miss.

Common mistakes

• Filling too thick in one go.
• Not letting it dry long enough.
• Sanding too much or too hard, damaging the tape.
• Working without a dust mask or safety glasses.

Working safely

Always wear a dust mask and safety glasses when sanding and ensure ventilation. Use a sturdy ladder and do not work above shoulder height without breaks. You can read more about safe working in our blog on safe working on the construction site. Also read our blog on putty knives, sanding tools and scrapers for materials, our blog on masking tape and protective film for masking and our blog on plastering a wall for other finishes.

Frequently asked questions

Do I always need joint tape?

For most seams between plasterboards, yes, so the seam does not crack. Follow the manufacturer's instructions.

How many layers of filler are needed?

Usually two or more thin layers. That depends on the board and the result you want.

When do I choose a professional?

For large areas, high walls or if you want a very smooth result.

Read also: How to paint a wall

Where can you find everything for this job?

At Saniso, the online store for DIYers and professionals, you will find tools, materials and personal protective equipment for your job.

• Browse our construction tools and our workwear and safety.
• Create a customer account and order easily.
• Working on a bigger project or want to hand over the job? Request a project quote.
• Book a showroom visit, at least 24 hours in advance.
• Not sure which material suits your job? Get in touch with us.

In doubt about the approach? Feel free to call in a professional.

Read also: Plastering a wall: DIY or professional? How to choose

Read also: Buying sanding blocks and sandpaper: what to look for

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