Plastering Corners

Filed Under: Do it yourself, Home repair, Remodeling    by: ITC

The main problem when plastering corners, whether external or internal, is getting a good, sharp angle. You will face a similar problem at the junction between the wall and ceiling. However, the techniques for dealing with both types of corner are not difficult to master.

There are two forms of guide you can use for forming an external corner: a timber batten or purpose-made metal beading.

The wooden batten is used as a thickness guide for the floating coat then the finishing coat on each wall. Nail it on to one wall so that it projects by the right amount beyond the other and use as a ground for that wall. Then, when the plaster has set, move it round the corner and repeat the process. Any sharp ridges on the apex of the corner should be sliced off with the trowel blade and then the corner rounded off with a block plane or rasp. With wallboard you must tape the angle first.

Two depths of metal beading are available to deal with masonry or gypsum board-clad walls and they can be fixed in place with plaster or galvanized nails. On wallboard, nails must be used. The beading acts as a ground for the floating coat on masonry walls. Before this hardens, cut back the level to allow for the finish coat. Trowel off flush with beading, leaving the nose exposed to provide a knock-resistant corner.

For dealing with internal corners, you need a long wood rule. Use this to rule the floating coat outwards from the corner.

After keying the floating coat, cut out the angle by running the corner of the trowel blade up and down it, holding the blade flat against each wall in turn. This will produce a sharp angle. The finish coat should be treated in the same manner. The final job is to hold the short side of the blade against one wall so the long side is just touching the fresh plaster. Hold the blade at 30′-40° and gently run it down the corner.

For finishing corners where both walls have been plastered, use a special V=shaped angle trowel. This produces a constant right angle in the fresh plaster. Load a small amount of plaster onto the angled blade of the trowel and run it lightly down the angle.


1. Reinforcing the external corner of a masonry wall with angle-bead; set it into blobs of plaster, 12in apart.

2. Plastering one wall; work away from the corner, using the nose of the bead as a thickness guide.

3. Plastering the adjoining wall in the same way: leave the nose just visible. Score the surface of both walls.

4. Applying the finishing coat, this time covering the nose: round off the corner by running a wet finger along the bead.

5. Securing angle-bead to the internal corner with galvanized nails; nail through the drywall into the stud.

6. Applying a coat of finishing plaster, working away from the corner; the nose should be left visible in this case.

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