How to install laminate flooring

Clicking the planks together is the easy part, and it is not where laminate floors fail. They fail three weeks later, when the middle of the room lifts into a ridge or a black line opens along one wall — and the cause is always something that was settled before the first plank went down.

Those decisions are numbers: how much gap, how far you can run before a transition, how far apart the end joints have to sit. The numbers are set by the installation sheet for the floor you actually bought, and the three biggest laminate makers in the US do not agree on them. Every figure on this page was read out of a manufacturer’s own document in July 2026, and every one is linked at the bottom so you can check it against yours.

The rules are brand-specific. Here are three of them, side by side

Requirement	Pergo laminate	Shaw glueless laminate	Mohawk RevWood
Perimeter expansion gap	3/8 in	1/4 in spacers	3/8 in minimum
Acclimation before laying	at least 48 h; 96 h in very dry or very humid climates	none required when the site is climate-controlled	48 h for 7 mm products; none for the rest under “normal conditions”
Conditions during installation	60–85 °F, 35–65% RH	65–85 °F, 35–65% RH	60–85 °F, 35–65% RH
Longest run without a transition	areas over 40 ft in length or width need a T-molding	“Floor spans should not exceed 40’ in any direction”; rooms over 26 × 40 ft need T-molding	expansion joints every 50 ft, both directions
Minimum end-joint stagger	not specified in the Essentials Guide	12–16 in	at least 6 in
Narrowest permitted last row	not specified	never less than 2 in	minimum 2 in
Subfloor flatness	3/16 in in a 10 ft radius, or 1/16 in over 3 ft	fill low spots over 1/8 in in 6 ft	unevenness over 1/16 in in 40 in must be smoothed

Read down the stagger row: 6 in and 12–16 in are both manufacturer minimums, and one is more than twice the other. Read the span row and the largest unbroken floor you are allowed to lay swings from 26 ft to 50 ft depending on whose planks are in the carton. Neither of those is a matter of taste, and neither is a number you can borrow from a video.

Shaw is worth a note on its own. Its beveled-edge glueless laminate instructions say to “use 1/4” spacers to maintain the proper expansion gap around the entire perimeter“; its own plan-and-install page says “ALWAYS leave a 1/2” expansion space around the perimeter of your space and any fixed objects.“ Both were live in July 2026. When one brand publishes two figures, the one that governs is the sheet packed with your product.

Step 1 — test the subfloor before you buy anything

This is the only step that can stop the project outright, so it goes first.

On the moisture limits, unusually, all three documents land in the same place: a calcium chloride test (ASTM F1869) must come back at 5 lb per 1,000 sq ft per 24 hours or less, an in-situ relative humidity probe (ASTM F2170) must read under 80%, and a wood subfloor must not exceed 12% moisture content. Shaw adds a first-pass screen with a concrete meter and puts the limit at 4%, sending you to a calcium chloride test above that. Pergo specifies how many tests: three across the first 1,000 sq ft, plus one more per additional 1,000.

Where they part company is new concrete. Pergo requires 60 days of curing before any flooring goes down. Mohawk scales it to thickness — “a new concrete floor must dry at least 1 week per 3/8-inch thickness up to 1-1/2 inches”, with anything thicker needing twice as long, and its worked example is a 2-1/2 in slab drying at least 8 weeks. A basement slab poured in the spring is not automatically ready in the autumn under either rule; test it.

Two conditions in the Pergo guide disqualify a room no matter what the meter says: a floor drain, and a sump pump anywhere in that slab.

Step 2 — flatness, measured with the straightedge they name

Every brand states flatness as a gap under a straightedge, and they use different straightedges, so the tolerances cannot be converted into each other. Pergo works off a 10 ft radius at 3/16 in, and also allows 1/16 in over 3 ft; Shaw asks you to check with a 6 ft straight edge and fill anything over 1/8 in; Mohawk wants nothing above 1/16 in over 40 in. Use the tool the document names. Buying a 6 ft straightedge is not optional equipment — it is how you find out whether the floor you are about to cover is legal to cover.

Fill low spots with a Portland cement leveling compound and let it dry fully; grind or sand the high ones. Pergo adds a limit that is easy to miss because it is about slope rather than bumps: the subfloor must not slope more than 1 inch in 6 feet, which is a separate test from flatness and catches settled joists that a straightedge laid across the dip will pass.

Step 3 — plan the field on paper, then order

Two things get decided here, and the second is where floors get ruined.

How much to buy. Pergo’s guide is explicit: add 10% to your square footage for a standard installation, 15% for a diagonal one. Laminate is then sold by the carton and carton coverage varies by style, so the square-foot figure has to be converted into whole boxes before you can order — the laminate flooring calculator does that conversion and the rounding, which on a small room is worth more than the waste allowance itself.

Where the transitions go. Compare the length and the width of the continuous floor — including any hallway running off it and any doorway wider than the threshold rule — against your brand’s span limit in the table above. If the floor exceeds it, a T-molding has to break it, and that has to be planned before you start laying, because it decides where a row stops. Pergo also requires a T-molding in any doorway under 4 ft wide regardless of the floor size; Shaw’s beveled-edge sheet puts the same requirement at doorways under 6 ft.

The last planning number is the first row. Both Shaw and Mohawk require the final row to finish at least 2 in wide, which means the first row usually has to be ripped narrower so the two ends match. Measure the room across the planks, divide by the plank width, and look at the remainder before you cut anything. Mohawk states the same rule for the vertical direction — check the doors still swing with the new floor thickness, allowing 3/8 in.

Step 4 — laying

Underlayment first, unless the planks carry a pad on the back, in which case a second layer is a warranty problem rather than an upgrade. Over concrete every one of these documents requires a 6-mil polyethylene vapor barrier regardless of the pad — Pergo wants the seams overlapped 8 in, Shaw 6 to 8 in and taped.

Saw the tongue off the long and short sides of the planks in the first row, so the sawn edges face the wall, and set spacers before you click anything. Mix planks from several cartons as you go — Shaw’s guidance is to “always work from multiple cartons to achieve a uniform appearance”, and since laminate is a printed product the repeats are visible if you empty one box at a time.

Stagger the rows to your brand’s minimum, and vary the starting length rather than stepping it evenly. Mohawk’s instruction is worth following literally: start the first row whole, the second at a third of a plank, the third at two-thirds, then whole, then half, then a quarter — the goal being to avoid a repeating staircase across the floor.

Step 5 — the perimeter is the floor’s only escape route

A floating floor moves. The gap you left is the space it moves into, and every plank of trim, door casing, pipe collar and kitchen island has to respect it. Nail quarter-round and baseboard into the wall, never down through the flooring — a single trim nail through a floating floor pins it and produces exactly the ridge you were trying to prevent.

In a bathroom, kitchen or laundry room, Pergo’s guide goes further and requires the 3/8 in perimeter space to be filled with 100% silicone sealant before the wall trim goes on, plus a sealed T-molding in the doorway to the adjoining room. That is a step, not a finishing touch: it is what keeps a spill on the surface instead of under it.

If you cannot find the sheet that came with your floor, the manufacturer’s site will have it by product line, and it is worth ten minutes of searching. On this page’s evidence, guessing gets you a gap that is half what it should be, a stagger that is a third of what it should be, and a floor with no transition where the maker requires one.