How to cut skirting board corners with a mitre saw

Before you cut

Measure along the wall at floor level and at the top of the skirting height, since walls can lean. Mark each board with its position and which end goes where. Decide which way each board will sit on the saw: upright against the fence or flat on the table. Tall skirting may need to be cut flat with a bevel if it is taller than your saw's vertical capacity.

Fit a fine tooth blade for clean ends; see mitre saw blades explained.

• Tape measure, pencil and a sliding bevel or angle finder.
• Mitre saw with a sharp fine tooth blade.
• Coping saw and file for scribing.
• Offcuts for test pieces.

External corners

External corners stick out into the room, such as around a chimney breast. Each piece is cut at 45 degrees so the long point is on the face of the board. With the board standing upright against the fence, swing the mitre to 45 degrees left for one piece and 45 degrees right for the other.

Test fit with offcuts first. If the joint opens at the front, the corner is more than 90 degrees; if it opens at the back, it is less. Adjust the angle by half a degree at a time.

1. 1

   Hold the board upright, back against the fence.

2. 2

   Set the mitre to 45 degrees in the right direction.

3. 3

   Cut with the long point on the face side.

4. 4

   Repeat the opposite angle on the other piece.

5. 5

   Test fit, adjust, then glue and pin the joint.

Internal corners: scribe or mitre?

You can mitre internal corners at 45 degrees, but if the walls are out of square or the boards shrink, the joint opens and shows a gap. Scribing, also called coping, avoids that. One board runs square into the corner. The other is cut to the shape of its profile so it sits over the first board like a jigsaw piece.

Scribed joints hide small errors in the wall angle and stay tight as timber moves, which is why most fitters prefer them.

How to scribe an internal corner

Fit the first board square into the corner. On the second board, cut an internal 45 degree mitre so the profile shows as a line along the face. Then follow that line with a coping saw, angling the cut back slightly so only the front edge touches. Clean up with a file and test fit.

1. 1

   Fit the first board square into the corner.

2. 2

   Cut a 45 degree internal mitre on the second board.

3. 3

   Darken the profile line with a pencil.

4. 4

   Cut along the line with a coping saw, angled back.

5. 5

   File to fit and test against the first board.

Corners that are not 90 degrees

Measure the wall angle with an angle finder or sliding bevel. For two pieces meeting at a corner of angle A, each piece is cut at (180 minus A) divided by 2 off square on the saw's mitre scale. A 90 degree corner gives 45; a 135 degree bay corner gives 22.5. Our mitre angle calculator works it out.

Always make a test cut on offcuts, as uneven plaster often needs a small tweak.

Use the mitre angle calculator →

Fixing and finishing

Fix skirting with adhesive, nails or screws into plugs depending on the wall. A cordless nailer speeds this up; see bundles in our power tool kit guide. Fill small gaps with decorator's caulk before painting.

Choosing a saw for skirting

Check your saw can cut your skirting height standing upright. Many 216 mm saws handle 120 to 150 mm skirting upright; the DeWalt DCS782N lists 165 mm. A double bevel saw saves flipping long boards. Compare saws in our mitre saw guide and sliding mitre saw guide, and read how to use a mitre saw.

Note:Clamp skirting firmly, especially tall boards standing upright, keep hands outside the no hands zone and let the blade stop before lifting. Wear eye and ear protection and follow the saw's manual.

Frequently asked questions

Which way do I cut skirting on a mitre saw? Usually standing upright with the back against the fence and the bottom edge on the table, so the mitre setting does the work.

Why are my mitred corners gapping? The wall is probably not 90 degrees, or the boards are not seated flat. Measure the angle and adjust, or scribe internal corners.

Can I scribe MDF skirting? Yes. MDF cuts cleanly with a coping saw, and scribed joints hide small errors.

Do I need a sliding saw for skirting? Not usually, if the skirting fits upright against the fence. Check your saw's vertical capacity.