Pattern floor waste and ordering guide

At a glance

Geometric cut-off only, our own calculation: whole blocks touching the room less the room area, no offcut reused, no defects or spare. Lowest to highest over start positions, mean in brackets. Planning figures; the partner workshop confirms the quantity on the approved layout.

Why a pattern floor costs more at the walls

A straight-lay floor is cut only at its ends and its last row, and the offcut from one row usually starts the next. A herringbone or chevron floor is cut along every wall, because the blocks meet the wall at an angle: a block that crosses the wall is a whole block of which only a triangle or a wedge is used. Little can be saved by re-using the offcut, because it is a thin triangle and every block along the wall leaves another one. So the waste is not a fixed percentage of the pattern. It is a perimeter effect: the cut-off is proportional to the length of wall and the length of the block, and it falls as the room grows.

Three things set it: the block length (a longer block leaves a bigger offcut at each wall), the room size (the same perimeter loss is spread over more floor in a big room), and where the pattern starts (the same room laid with the pattern shifted gives a different cut-off). The sheet below measures all three by geometry and gives the range, not one number.

Everything here is the geometric cut-off of the pattern alone. It does not include blocks rejected for grade or defect, saw kerf, damage on site or a spare allowance for later repairs. It does not assume any offcut is reused. A partner workshop that cuts and fits its own panels or reuses offcuts in cut-outs and borders may plan around lower figures; ask it for its own.

How much, by pattern, room and block

For a block 90 mm wide and 450 mm long (five times the width), in three room sizes. Each cell is the lowest and the highest cut-off over a grid of start positions across one pattern period, with the mean in brackets, as a percentage of the room area:

Two things stand out. The mean is the planning number when the start position is not yet drawn; the range is why a percentage quoted without a room is of little use. And the zigzag along the walls (the usual herringbone look, blocks at 45 degrees to the wall) cuts more than the same blocks laid square to the walls, because it makes a pointed edge against every wall. Chevron and 45-degree herringbone are close in all three rooms.

The block length matters as much as the pattern. In a 4 x 6 m room:

A longer block costs more floor at the walls even though it needs fewer joints. The same arithmetic is in our herringbone and chevron sheet for one room; here it is extended to three rooms and three block sizes.

A worked example: 40 m2, with and without a border

A worked example. A 5.0 x 8.0 m room (40 m²) in 90 x 450 mm herringbone with the zigzag along the walls. The same geometry gives a cut-off of 6% at the best start position, 13% on average and 13% at the worst, so the blocks to order, before any allowance for defects or repairs, are between 42.4 and 45.4 m² (mean 45.2 m²).

Now add a straight-lay border 300 mm wide. The border takes 7.4 m² and leaves a field of 32.6 m², which is cut against the border in the same way it was cut against the walls: 13% to 22% (mean 14%), so 36.9 to 39.6 m² of blocks for the field. The border boards are ordered on top, as 7.4 m² net plus the mitre cuts at the four corners (each corner loses two triangles, 0.36 m² in all for a 300 mm border) and the end-of-board cut-off along each side, which depends on the board length and whether the offcut is reused. The total for the room is therefore not lower than the plain herringbone: a border does not save floor, because the pattern is still cut against an edge, only now against the border instead of the wall. What it changes is how the pattern ends. See borders, frames, medallions and inlays.

For quantity purposes the lesson is to ask for the layout drawing. The partner workshop can count the blocks on the actual plan, with the start position the design needs, and that count replaces any percentage.

Straight lay, for comparison

Straight lay is predictable. Rows run along the room; each row ends in a cut board and the last row is ripped to width. Two exact results:

• Last row. Ripping the last row to width wastes on average half a board width over the room width: for 190 mm boards that is about 3% in a 3 m wide room, 2.4% in 4 m and 1.2% in 8 m (mean of the waste over all widths, half the board width divided by the room width).
• Row ends. If the cut-off at the end of a row is never reused, the average loss is half a board length per row: about 25% of a 4 m row for 2,000 mm boards. In practice the offcut starts the next row, subject to the minimum stagger in the specification, so the real loss is much lower: the table above gives the no-reuse figure only to show why reuse matters.

Defects and grade-out then add to this, depending on the grade; see wood flooring grades. And in a pattern floor made of panels the waste moves from the site to the workshop: see parquet panels against loose lay.

What to put in the quantity clause

The aim is that the quantity in the tender is the same quantity every bidder priced. Four things belong in the clause.

• Net area and waste, separately. State the net floor area as drawn, and the waste allowance as its own line, so that two quotes can be compared on the net area. A quantity that does not say whether waste is included is the commonest reason two quotes differ.
• Waste by pattern and room. Ask for the waste the partner has planned for each pattern in each room, from its layout drawing, rather than one percentage for the job.
• One batch. Buy the whole quantity, including the allowance, from one lot, so that colour and grade match. Say what happens if the allowance runs short: a top-up from another lot is a different colour.
• Spare. Say whether a spare for later repairs is included, how much, how it is stored and who holds it. We give no figure: it is a client decision, and the partner confirms what it can supply from the same lot.

These figures are planning figures only. The partner workshop confirms the quantity on the approved layout.

Floor area [ ] m² net as drawing [ref]. Waste allowance for [pattern] in [room], [ ] % as the partner's layout drawing [ref], shown as a separate line from the net area. The quantity supplied is [net area plus allowance] from one production lot.

Before ordering, the partner is to submit a layout drawing for each pattern area showing the pattern, block size, start position, setting-out lines, border, and the cut blocks at every wall and threshold, from which the quantity is counted. The design team approves it. A change to the start position or the block size after approval is a variation.

All material for [area] is to be from one lot and one grade. Spare for repairs: [ ] m² from the same lot [supplied / not supplied / to be held by partner]. A top-up from a different lot is not to be used without written approval.

Standards and sources

• Our sheet: Herringbone against chevron: the first, single-room trial of cut-off.
• Geometry, not a standard: the cut-off numbers are our own calculation (whole blocks touching the room less the room area). No standard or primary document gives a waste factor for a timber floor.

Questions we are asked

How much extra herringbone should I order?

It depends on the room, the block length and where the pattern starts. For 90 x 450 mm blocks our geometry gives a cut-off of roughly 7 to 12% in an 8 x 10 m room, 10 to 20% in a 4 x 6 m room and 14 to 29% in a 3 x 4 m room, before any allowance for defects or repairs and with no offcut reused. Ask the partner for a layout drawing and count from it.

Is chevron more wasteful than herringbone?

Close in our calculation: for 90 x 450 mm blocks the means are within a point or two of each other in each room, and herringbone laid square to the walls is lower than either. The difference between them is smaller than the difference made by the room size and the start position.

Does a border reduce waste?

Not in our worked example. A border takes floor area and the pattern is then cut against the border instead of the wall, so the total ordered is about the same or a little more. A border changes how the pattern ends, not how much floor it needs.

Why does a bigger room waste proportionally less?

Because the cut-off is a perimeter effect. It is proportional to the length of wall and the block length, and a larger room has more floor for each metre of wall. The same blocks give about 14 to 29% in a 3 x 4 m room and 7 to 12% in an 8 x 10 m room.

What percentage do suppliers quote?

Supplier guides give single percentages that disagree with each other by several points and often do not say the room or the block size. We do not use them. Our figures are geometry, labelled as planning figures, and the partner confirms the quantity on the approved layout.

Should the allowance for repairs be in the order?

Say so in the clause, as its own line, and name who holds it and from which lot. A top-up later may come from another lot and a different colour. We give no figure: it is the client's decision.