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How to plaster drywall or plasterboard joints

Plastering Wall joints

Date created

Friday, 29 April, 2016 - 14:54

Last updated

Friday, 29 April, 2016 - 15:36

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Setting of plastering plasterboard joints (plasterboard is sometimes called drywall, and gyprock) is used to cover each joint in plasterboard. So when the plasterboard have been 'set' and then sanded you can paint the walls without seeing any joins. So how do you plaster the plasterboard joints? With some basic tools and the right materials we show you how to get the best results.
Appling plaster to a wall

How to plaster drywall or plasterboard joints

To plaster wall joints you will need the following:

  • 3 Clean buckets
  • Broad knifes 120mm, 250mm, and 300mm approx. Sizes
  • Paper or glass tape
  • Base Coat
  • Finishing compound
  • Sanding block or plasterboard sander
  • Corner trowel

After the sheets have been installed you are ready to plaster the joins. If you are using glass fiber tape place this on all of the joins including the corners first as it is self adhesive. If you have a large amount of joins to set use a longer setting base coat 60-120min. However if you have one room to repair or join you can use 45 min base coat.

Step one: Mix, tape and apply

Mix the base coat with clean water to a toothpaste consistency. It should still stick to the trowel; if it is too loose add a small amount of the dry base coat and remix. Using the small trowel or broad knife fill the joins flush with the wall/ceiling board. If you are using paper tape press the tape into the wet base coat that you have already placed plastering into the join and then trowel a small amount of base coat over the paper tape just to cover it and bed in the tape. If you have used self adhesive fibre glass tape there is no need to bed in the tape so just fill the join. See photo.

Step two: Second coat

Once the first coat (step one) has gone off or hard you will need to apply another thin coat of base coat with a wider broad knife (approx 200 to 250mm). This covers the join and spreads beyond the first coat to widen the join. This helps to blend the joint into the wall board. see photo.

Step three: Finish coat

When the second coat has gone off or hard you can apply the finishing compound. This is a premixed product that is applied straight from the bucket. (Sometimes it is best to mix it first). Using the largest broad knife apply a thin coat of finishing compound over the base coat so that it covers the base coat completely and is spread 50mm beyond it. see photo.


Corner joins are done the same way except you use the corner trowel. finished plaster jointsApply the same way as above.


The better you get the joins the less sanding you will have to do. Wait until the finishing compound has completely dried before you sand. The finishing compound must dry it does not go off like the base coat. Finishing compound is a soft sand product so it is easy to sand. When sanding be sure to feather out the edges of the joint so the joint will not be seen under the paint. If you are plastering a larger job hire or buy a plasterboard sander with a vacuum. These do a great job and at sanding the joint flat and sucking the dust away. After using a plasterboard sander go over the join and check it and hand sand any small imperfections. After you have sanded the joins smooth you are ready to install your cornice.