How much skirting do I need for a 4.2 m by 3.6 m room?

About 14.8 m: the 15.6 m perimeter less a 0.826 m doorway. In 2.4 m lengths that is 7 lengths if an offcut can fill a short piece, or 8 if you round each wall up. BuildBatch's skirting board calculator does not take the doorway off, because the two short runs beside a door usually come out of the same lengths, so it counts the whole 15.6 m and says 8.

Do I need beading if I take the skirting off?

Usually not. If the skirting comes off and goes back on over the new floor, it covers the expansion gap itself. Beading or scotia is for when the skirting stays where it is.

How to measure for skirting board, beading and scotia

Measure every wall at floor level, add the lengths together and take off the width of each doorway: that is the run of skirting, beading or scotia the room needs. Then count the lengths to buy wall by wall, rounding each wall up, because every wall is a separate run with its own cuts.

Skirting, beading or scotia?

Skirting board is the board along the bottom of the wall.
Beading and scotia are thin strips fixed along the foot of the skirting to cover the expansion gap a floating floor needs at the walls. Quadrant beading is a quarter circle; scotia has a hollow curve.
If the old skirting comes off and goes back on over the new floor, the skirting covers the gap and no beading is needed. If it stays where it is, beading or scotia covers the gap.

The run to measure is the same for all three.

Measuring the run

Measure each wall at floor level, corner to corner, and write the lengths down in order.
Add them. That is the perimeter; for a rectangle it is 2 × (length + width).
Take off each doorway, measured across the outside of its frame, where the skirting stops.
Take off anything the skirting will not run along, such as a fitted cupboard.
Count every wall a chimney breast or a bay adds. Each side of a chimney breast is a run of its own; see measuring a room with a bay window, alcoves or a chimney breast.

From metres to lengths

Skirting, beading and scotia are sold in lengths. 2.4 m is common, but check what your shop sells. There are two ways to count:

The whole run ÷ the length sold, rounded up. The fewest you could buy, if offcuts fill every short piece.
Each wall ÷ the length sold, rounded up, then added. The safe count, because it assumes no offcut is ever long enough to use elsewhere.

The right number is usually one of the two or in between, and the wall lengths decide which.

Joints, corners and spares

Long walls. A wall longer than one length needs a joint. Joints are often cut at an angle so they show less, which uses a little extra length for the overlap.
Internal corners, the ordinary corners of a room, are mitred or scribed. Measured along the wall, the piece is no longer than the wall.
External corners, such as the front corners of a chimney breast, are mitred, and each piece runs past the corner of the wall by about the thickness of the board. Allow a little extra there.
A spare. One wrong cut costs a whole length, and one spare length covers it.

Worked example

The example room is 4.2 m × 3.6 m, with one door 0.826 m wide in one of the 3.6 m walls, 0.5 m from a corner.

Perimeter: 2 × (4.2 + 3.6) = 15.6 m
Less the doorway: 15.6 − 0.826 = 14.774 m, about 14.8 m of skirting
Whole run in 2.4 m lengths: 14.774 ÷ 2.4 = 6.16, so 7 lengths

Now wall by wall. The door wall is two short pieces: 0.5 m on one side of the door and 3.6 − 0.5 − 0.826 = 2.274 m on the other.

Run	Length	2.4 m lengths	Offcut
Wall 1	4.2 m	2	0.6 m
Wall 2	3.6 m	2	1.2 m
Wall 3	4.2 m	2	0.6 m
Door wall, long side	2.274 m	1	0.126 m
Door wall, short side	0.5 m	1	1.9 m
Total	14.774 m	8

Round each run up and you buy 8 lengths, 19.2 m. But the 0.5 m piece can come out of one of the 0.6 m offcuts, even after a little for the joint on that wall, which brings it down to 7 lengths, 16.8 m. Buy 7 if you are confident with the saw, 8 if you want the spare.

Beading or scotia along the same 14.8 m is counted the same way.

Do it with BuildBatch

Open the Room Refresh Batch with flooring chosen and add the doors to the room. The batch lists “Beading, scotia or new skirting” with the length round the room, not counting doorways, marked Check first: divide it by the length your shop sells and round up.

What this guide does not cover

Fixing skirting to the wall, which depends on the wall and on what runs behind it: check first. Painting it, since woodwork paint has its own coverage figures. Profiles and heights, which come down to taste and to matching what is already there. Cutting round pipes.