Laminate in a 5 × 3.7 m living room: the complete order list

A straightforward rectangular room that still contains the single decision most people get wrong — and only find out about when they reach the far wall.

The room

• 5.0 m × 3.7 m, rectangular, square corners
• One doorway, 0.9 m wide, into a hallway
• Concrete subfloor, flat, no damp-proof membrane below the slab
• Planks 1285 × 192 mm, 8 to a pack
• Laying straight, along the 5 m direction

Step 1 — how much flooring

Area is 5.0 × 3.7 = 18.5 m². Laying straight along the long wall carries an 8% allowance, not 10%, because the offcut from the end of each row starts the next row — which is also how you get the required stagger. The room is simple and well over 12 m², so there is no shape or small-room addition.

That means buying 19.98 m². Each pack covers 1.285 × 0.192 × 8 = 1.974 m², so 11 packs — 21.7 m², leaving about 3.2 m² over, roughly 13 planks.

Keep six of those. A dropped tool or a dragged sofa leg means lifting back to the damage and replacing a plank, and a discontinued décor makes that impossible.

Step 2 — the last row, before you lay anything

This is the decision that separates a floor that looks deliberate from one that looks like it ran out of room.

With a 10 mm expansion gap at each side, the covered width is 3700 − 20 = 3680 mm. Divided by the 192 mm plank width that is 19.17 rows, so you need 20 rows — and the twentieth is only 3680 − (19 × 192) = 32 mm wide.

A 32 mm sliver is too narrow to click in reliably, fragile, and lands against the far wall where the eye goes. The fix has to happen before the first plank goes down: rip the first row narrower so the first and last rows come out equal.

first row width = (3680 − 18 × 192) ÷ 2 = (3680 − 3456) ÷ 2 = 112 mm

Cut the first row to 112 mm and the last row is also 112 mm. Both are wide enough to handle, the floor reads as centred, and nobody can tell the room was not built to suit the flooring.

Step 3 — what goes underneath

The subfloor is concrete with no membrane below the slab, so two separate layers are needed and people routinely buy only one:

• Damp-proof membrane — a polythene sheet, taped at the laps and turned up the walls behind the skirting. Concrete transmits moisture indefinitely, and laminate that absorbs it swells at the joints and never recovers.
• Underlay — foam or fibre for acoustics, minor levelling and comfort underfoot.

Some products combine both in a single sheet, and some planks have backing already attached. Check yours before buying — doubling up on foam is a real mistake, because too much compression under a click joint flexes the tongues until they fail.

Underlay: 18.5 m² plus 5% for laps = 19.4 m², so 2 rolls at 15 m².

Step 4 — the edges

The expansion gap has to exist and has to be hidden. Perimeter is 2 × (5.0 + 3.7) = 17.4 m, less 0.9 m for the doorway = 16.5 m. With 10% for mitres, 8 lengths of 2.4 m beading.

Either remove the skirting and refit it over the flooring, or leave it and fit scotia beading against it. Removing and refitting looks considerably better and costs a day. Whichever you choose, the beading pins to the skirting, never to the floor — pinning through the flooring bolts it in place and defeats the entire point of the gap.

One threshold bar for the doorway, sized to the height difference with whatever is in the hall.

The full order list

What people forget

• Acclimatisation. Packs must sit flat and unopened in the room for 48 hours so the boards reach its humidity. Fitting straight off the van is the usual cause of a floor that peaks or gaps a month later, and it voids most warranties.
• Door clearance. You are adding 10–20 mm of floor height. Check every door swings clear before you start, and take the internal doors off and trim them while the room is empty.
• The 300 mm stagger. End joints in adjacent rows must be at least 300 mm apart. Cut each row's first plank from the previous row's offcut and it takes care of itself — which is exactly where the 8% waste figure comes from.
• Which direction. Along the long wall means fewer rows and less waste. Along the light from the window means the joints cast far less shadow. When they conflict, follow the light — the joints are what you will actually notice.
• The gap is not decorative. 10 mm all the way round, including around pipes and against door frames. A floating floor that cannot move will buckle in the middle of the room on the first humid week.

Order of work

1. Deliver the packs, lay them flat in the room, wait 48 hours
2. Remove skirting if you are refitting it; take off internal doors and trim them
3. Check the subfloor is flat to within 3 mm over 2 m; level it if not
4. Lay the membrane, tape the laps, turn it up the walls
5. Lay the underlay, butted not overlapped
6. Rip the first row to 112 mm and lay away from the longest wall
7. Work across, keeping 10 mm spacers at every edge
8. Refit skirting or fit beading, fit the threshold bar, remove the spacers

A day and a half for a room this size, plus the two days of acclimatisation before you can begin.

Run your own version

• Flooring calculator — packs, underlay, beading and the last-row check
• Waste factor table — why straight-along is 8% and herringbone is 20%
• How to measure a room properly — measure the widest point, and check the diagonals

Last reviewed 2026-09-18. Quantities are for the room described. Follow your manufacturer's fitting instructions, which override anything here.