Pricing a whole floor one room at a time is how budgets go wrong, because the rounding goes the wrong way. Each room needs a whole number of packs, and each of those roundings is upward, so four rooms priced separately can need two or three packs more than the same four rooms priced together — and sometimes fewer, if one room is small enough to be covered by the leftovers from the others. This puts every room on its own row with its own area, pack count and cost, then totals them, so you can see which room is driving the number and whether buying them as one job changes the answer.
Rooms, coverage and price
Set a room to zero on both sides to leave it out — the row drops off the table.
Printed on the pack. Laminate is commonly around 2.2 m², engineered wood around 1.5.
Eight percent for a straight lay in rectangular rooms; more for diagonal or herringbone.
Result
Why a whole house is not the sum of its rooms
Flooring is sold in packs, and packs are whole. That single fact produces a behaviour that surprises people: the total for a house is not the total of the room-by-room figures, and it can be either higher or lower depending on where the fractional packs fall. If each of three rooms needs 4.3 packs, each rounds to five, and you buy fifteen. Added together first, 12.9 packs rounds to thirteen. Two packs difference, purely from the order in which you did the arithmetic.
It can go the other way. Three rooms each needing 4.9 packs round to fifteen, while the combined 14.7 rounds to fifteen as well — no difference. But four rooms each needing 2.1 packs round to twelve, while the combined 8.4 rounds to nine. In that case buying separately costs three packs more.
Which order is correct depends on whether the leftovers are actually usable across rooms. If the rooms are being done at the same time in the same material, they are — a part pack from the main room goes straight into the second. If they are being done a year apart, or in different materials, they are not, and the room-by-room figure is the honest one.
Measuring rooms properly
Measure to the widest points, into door reveals and into bay windows, because flooring runs there too. Measure the room, not the old carpet. Then subtract anything permanent that the flooring will not go under: a kitchen island, a fitted chimney breast, a built-in cupboard. Flooring goes to the skirting, not to the wall, so the room's floor area is slightly larger than the dimensions measured at skirting level suggest, and the difference is worth a fraction of a pack on a large job.
For rooms that are not rectangular, split them into rectangles and add them. An L-shaped room is two rectangles; a room with a bay is a rectangle plus a half-hexagon that can be treated as a triangle or a trapezoid. The room area figure handles the L and the trapezoid directly and lets you add a waste allowance before you put the number in here.
Measure twice, and write the numbers down as you go. The most common failure on a multi-room job is a transposed digit in one room's dimensions, which is invisible in a total and obvious in a table — another reason to look at the rooms individually rather than only at the bottom line.
| Feature | Include? | Why |
|---|---|---|
| Floor area to the walls | Yes | Flooring runs under the skirting |
| Door reveals | Yes | The floor continues into the reveal |
| Bay window floor | Yes | It is floor, and it is usually a cut-up area |
| Fitted kitchen units | No | Flooring usually stops at the plinth |
| Chimney breast | No | If it is structural and floor-to-ceiling |
| Under a bath | Yes | Cheaper to floor it than to scribe around it |
| Threshold between rooms | Yes | It needs a strip and a little material |
Which room is actually expensive
Splitting the job by room tells you something a total cannot: which room is driving the cost. Usually it is not the largest room. Small rooms have a worse ratio of perimeter to area, so they waste proportionally more, and a room with a bay, a fireplace or a fitted wardrobe wastes more again. A four-square-metre bathroom can easily need a higher waste allowance than a thirty-square-metre living room, and if you apply one percentage everywhere you will under-order for the bathroom and over-order for the rest.
It also tells you where to economise. If the table shows the main room taking half the packs, that is where a cheaper material makes a real difference, and the small rooms are where you can afford the better product, because the quantity is small enough that the price difference barely registers.
Flooring is produced in batches with slight colour variation between them. Order every room from one batch, at the same time, even if the rooms are being fitted later.
Take delivery before the fitter arrives and let it acclimatise in the room for the period the manufacturer specifies — usually forty-eight hours. Wood and laminate both move.
A worked example
- Area of each room5.4 by 4.2 is 22.68 m²; 4.0 by 3.5 is 14.0 m²; 3.6 by 3.0 is 10.8 m². Total 47.48 m².
- Waste and coverageAt eight percent and 2.2 m² per pack, the rooms need 11.13, 6.87 and 5.30 packs.
- Round each one upThose become 12, 7 and 6 — twenty-five packs, at $38 each, $950.
- Compare with one purchaseThe whole 47.48 m² at once needs 23.32 packs, which rounds to 24. Doing the rooms in one go saves one pack, $38.
- Check the cost per square metre$950 over 47.48 m² is $20.01 per square metre — the number to compare against a fitted quote.
Twenty dollars a square metre is material only. A fitted quote will include underlay, adhesive, skirting or beading, door bars, and the labour, and it will usually be two to three times the material figure. Knowing the material cost separately is what lets you tell whether a quote is reasonable.
What the total does not include
Underlay is the one people forget, and it is sold in rolls with its own coverage, usually fifteen square metres, with its own waste. It needs the same calculation again with a different number. Adhesive, where the floor is glued rather than floated, is quoted per square metre of coverage by the trowel size, and the adhesive figure works the same way for a glued floor as for a tiled one.
Transitions are the second omission. Every doorway between two floors needs a strip, and a house with five rooms has four or five thresholds. They are cheap individually and annoying to be without. Skirting or beading around the perimeter is the third: it is priced by length, not by area, and the skirting length figure is the quickest way to get it.
Do
- Measure into reveals, bays and thresholds.
- Order all rooms in one batch, even if they are fitted later.
- Price the rooms separately if they are being done at different times.
- Use a higher waste allowance for the small, cut-up rooms.
- Add underlay, transitions and beading as separate lines.
Avoid
- Applying one waste percentage to rooms of very different sizes.
- Forgetting that packs are whole and that rounding compounds across rooms.
- Measuring the old carpet rather than the floor.
- Ordering room by room months apart and expecting the colour to match.
- Comparing a material-only figure with a fully fitted quote.
Where the numbers stop being true
This treats every room as a rectangle and applies one waste allowance to all of them. If your rooms differ sharply in shape or size, run the calculation with a different allowance for each — or use the waste rate comparison to see what the pattern and the room shape are actually costing you before you fix the percentage.
It assumes one material throughout. Mixed materials mean the leftovers cannot cross between rooms, which pushes the answer back towards the room-by-room figure and away from the combined one. It also assumes full packs are available: if a discontinued line is down to the stock on the shelf, the arithmetic stops mattering.
Nothing here accounts for the direction the boards run, which changes both the waste and the look. Running boards along the longest dimension usually reduces cuts and makes a room feel longer; running them across a hallway makes it feel wider. The length of the flooring run is worth checking before you commit to a direction, because a change of direction can move the pack count by one.
How the figures are produced
Each room's area is length times width. Each room's packs are its area, plus the waste percentage, divided by the coverage per pack and rounded up to a whole pack. Costs are packs times price. The total area is the sum of the rooms, the pack total is the sum of the rounded figures, and the combined figure applies the same waste to the summed area before rounding once. The difference between the two is shown because it is the number that decides whether to do the house in one go.
Questions people ask
Should I price the rooms separately or all together?
Together, if they are being done at the same time in the same material, because leftovers cross between rooms. Separately if the rooms are months apart or in different materials.
Why does the total change when I add a tiny room?
Because a small room can still need a whole pack. One square metre at 2.2 m² per pack rounds up to one pack, and that pack is a full price for a tenth of its contents.
How much waste should I allow?
Eight percent for a straight lay in rectangular rooms. Ten to twelve for diagonal, fifteen or more for herringbone, and more again for small or cut-up rooms.
Do I need underlay as well?
For laminate and engineered wood, almost always, and it is sold separately by the roll. Check whether the flooring has it integrated before buying.
What about the thresholds between rooms?
One strip per doorway where two floors meet, plus a reducer where the new floor meets a different height. Count the doorways and order that many.
Can I use leftovers from one room in another?
Yes if the material and the batch are the same and the rooms are being done together. That is exactly what the combined figure assumes, and it is why it can be lower.