How To Cut Ceiling Corners

Using a miter box

If the corners and walls in the room are even, you can use a special carpentry tool. a miter box. This is an inverted U-shaped chute in which the mowing line is marked for cutting at 90 ° and 45 °. The part in which you need to make a gash is laid inside, a saw is inserted into the guides. The part is held in place, cut at the desired angle.

ceiling, corners

This is what the miter box looks like. Can be plastic, wood or metal

In the case of skirting boards, not everything is so simple: they must simultaneously adhere to two surfaces, therefore they must be pressed against one or the other wall of the miter box. When working with ceilings, they are pressed in the side closest to you.

The sequence of actions when finishing the outer corner, you need to make a gash at an angle of 45 degrees. Place the miter box in front of you. Trying on how the plinth will be located, determining which part of it will be attached to the ceiling. In order not to get confused and cut off the ceiling plinth correctly, put the strip that will be located on the right on the right, the one on the left on the left.

How to cut a corner on a ceiling plinth: install it correctly in a miter box

Press the part that is on the ceiling to the bottom of the miter box. The other side is closer to you and raised. Lean it on the wall of the device so that it does not stagger when cutting. That is, the front of the skirting board turns out to be turned away from you. Do the cutting direction as shown in the photo below. By folding the two cut pieces together, you get a protruding outer or outer corner.

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How to make the outer corner of a skirting board using a chair

First put the cut-off parts in place “dry”, without applying glue. If the geometry of the corner is not so perfect, you can tweak it a little with a knife. It is easier to cover small errors with a special putty.

The situation is very similar with the inner corner of the skirting board. First you try on which side will be on the ceiling, press this part to the bottom of the miter box, lean the second part on the wall closest to you and make cuts as shown in the photo below.

How to make an inner corner of a ceiling plinth using a miter box

And again, first try on without applying glue, if necessary, slightly adjust. Then apply a thin bead of glue to both surfaces that will adhere to the wall or ceiling.

Your own version of how to use the miter box correctly is shown in the video.

Method 2. trimming the edge of the skirting board without the help of a miter box

If you don‘t want to waste time making a miter box, then you can make the markings directly on the ceiling! To do this, the edge of the plinth is cut off at a right angle, then the plank is applied to the corner as it is planned to be installed, and the border of the plinth is marked.

Marking the line of the first skirting board

Do the same with the second bar.

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Marking the line of the second plinth

After spreading the lines, they mark the point of intersection of the two lines directly on the planks. this will be the line for cutting the edges of adjacent skirting boards.

Mark the crossing point on the skirting boards

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Cut skirting boards are joined in the corner

Fillet trimming

Thus, cutting corners when gluing baseboards is one of the most difficult and responsible procedures for which it is advisable to use a special device. a miter box. which allows you to cut the baseboard at an angle of 45 degrees. If the angle between the walls is not straight, you have to use manual marking. Cutting tools depend on the material of the baseboard.

What tools will be needed?

For ceiling plinths, the following tools may come in handy, depending on the chosen method of work:

  • Saw on wood. Suitable for working with wooden ceiling plinths.
  • Metal sheet. Suitable for other types of skirting boards (foam, plastic, etc.).
  • Miter box. The tool is a chute, which has the shape of an inverted P, where mowing lines are outlined at angles of 45 ° and 90 ° for cutting.
  • Electric miter saw. Can be used instead of a miter box, helps to achieve high cutting accuracy.
  • Electric jigsaw. Easy to operate, with the help of it you can efficiently and correctly cut a corner without burrs.
  • Stationery or construction knife. Suitable for Styrofoam skirting boards, it is important that it has an excellent cutting blade, and therefore must be well sharpened.

Skirting materials and cutting methods

First of all, let’s try to determine what the fillet can be made of, and what specific material is better to cut.

On sale today you can find products made of polystyrene (polyvinyl chloride), wood, expanded polystyrene and polyurethane.


Perhaps one of the cheapest skirting boards is made of polystyrene, which is a fragile, soft and brittle material.

Even fingers can dent them, and they easily form creases and defects. It is quite difficult to cut a beautifully and evenly corner at a baseboard based on polyvinyl chloride.

For an inexperienced craftsman, a large amount of purchased material can go to waste for this very reason. Also, this polymer has high electrostatic properties, which explains its ability to collect dust.

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It is most convenient to cut such a plinth with a hacksaw or a sharp construction knife.

Expanded polystyrene

Products made of expanded polystyrene are also inexpensive, although this material is a more durable analogue of traditional foam.

Can also be cut with a sharp tool.

Extruded expanded polystyrene

Extruded polystyrene skirting boards are slightly more expensive, they are somewhat denser and more difficult to cut. But they crumble and break much less.

Therefore, it is more convenient and easier to cut them. For this purpose, it is convenient to use a hacksaw or a sharp knife.


Polyurethane ceiling skirting boards are currently perhaps one of the most expensive.

But they justify their cost: moisture resistant, fairly strong and dense, quite elastic.

The skirting above the stove can deform and even crackle slightly.

They are perfectly cut with a special knife without forming crumb. But these products are very sensitive to temperature changes.


Wooden skirting boards for the ceiling are quite heavy and dense products, solid and durable.

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They lend themselves well to processing with a special fine-toothed hacksaw. You can also use a reliable metal blade. So how to cut the ceiling plinth correctly?

How to properly cut corners on baguettes (ceiling plinth) video

Modern renovation involves a beautiful design of the joints of the walls and ceiling. This becomes possible when using a ceiling plinth. Installation of such a decorative ornament only at first glance may seem like an easy matter.

However, this is a painstaking and difficult job. Those who make do-it-yourself apartment renovations may have a quite natural question: how to cut the corners of the ceiling plinth? The guidelines below will help you figure it out.