Do I need underlay for click vinyl?

Two makers rule out an extra underlay where the vinyl has underlay attached or built in. Amtico says none should ever be used on Click Smart, which has an integral underlay, and Quick-Step says an additional underlay is not allowed on vinyl with underlay attached. Karndean does not mention attached underlay: it says a separate underlay is not normally advised, and to ask the floor covering supplier. Read the pack first.

Do the makers agree on the expansion gap?

No. The rates are stated on different bases: 1.5 mm per metre of floor surface for EGGER, 1 mm per metre of floor width for Quick-Step and 2 mm for every metre span for Woodpecker. The minimums run from 5 mm to 15 mm. Read the gap in your own floor's guide before you buy spacers.

Laminate, vinyl or engineered wood: what changes on your list

Four things change on the buying list between laminate, click vinyl, glue-down vinyl and engineered wood: whether you buy an underlay, whether a moisture layer goes under it on concrete, how wide a gap the guide asks for, and how much extra to order. Six makers’ own documents agree on some of it and give different numbers for the rest. Only topics that at least two makers cover, for that floor, are on this page.

How this page was made

Kind of page: Worked out, not tested. Every claim is a maker’s own, read on 29 September 2026 from its installation guide, questions page or product page: Amtico, EGGER, Kährs, Karndean, Quick-Step and Woodpecker. Nothing was measured or fitted. The Quick-Step and EGGER documents are international editions, not UK-only ones, and newer editions than the ones linked were not looked for.

It was drafted with AI tools, and the figures were checked against the makers’ pages by a second AI tool. No tradesperson and no other person has checked it. Prices are left out on purpose. How BuildBatch compares products says what “worked out” means and what every page like this must show.

Which floors, which makers

Laminate: EGGER and Quick-Step.
Click vinyl, also called rigid core: Amtico, Karndean and Quick-Step.
Glue-down vinyl: Amtico and Karndean.
Engineered wood: Kährs, Quick-Step and Woodpecker. Woodpecker’s Harlech page says real wood engineered, with a 4 mm wear layer on a plywood core. Quick-Step’s document is titled “Wood flooring” and Kährs’s source is a general questions page, so filing them under engineered wood is BuildBatch’s own grouping.

Each table below is by floor, then by maker, A to Z. The sources under each table are by maker, A to Z too. Where makers give different numbers they are shown side by side, not merged into one rule. Glue-down vinyl is only in the moisture table: for its underlay, its gap and its waste only one maker gave a figure, so they are not covered here.

Underlay

Underlay: what the makers’ installation guides say, by floor
Maker	What the maker says
Laminate
EGGER	The laminate ranges have no integrated underlay. On a mineral subfloor, a system-specific insulation underlay goes on top of the moisture film, to improve impact noise insulation.
Quick-Step	Says to always use its own underlay, and that on a mineral subfloor the underlay includes a vapour barrier.
Click vinyl (rigid core)
Amtico	Says Click Smart has an underlay built in, and that no other underlay should ever be used with it.
Karndean	Says a separate underlay is not normally advised, and to ask the floor covering supplier for details. It says nothing about underlay attached to the vinyl.
Quick-Step	Says an additional underlay is “not allowed” where the vinyl has underlay attached.
Engineered wood
Kährs	Says a floating floor needs an underlay.
Quick-Step	Floating: says to always use its own underlay, with a vapour barrier included on a mineral subfloor. Glued down, it uses glue and a trowel instead.
Woodpecker (Harlech)	Says the underlay depends on the subfloor, and advises an underlay with a built-in damp proof membrane for most installations.

Sources. All read on 29 September 2026. A date in a link's words is printed on the document, except where the words say it comes from a document code or a file name: Amtico Click Smart installation guidelines, March 2023 (from the document code ACS-IN-20230314); EGGER Flooring Collection 25+ installation instruction, edition 09/2024 (from the document code printed at its end); Kährs UK questions page; Karndean rigid core installation guidelines, January 2024; Quick-Step laminate installation guide, version 07.2026; Quick-Step rigid click vinyl installation guide, version 07.2026; Quick-Step wood flooring installation guide, version 07.2026; Woodpecker Harlech installation instructions, no date printed (the file name says version 21 and the address says April 2025); Woodpecker Harlech product page.

On your list: Laminate and floated engineered wood: an underlay, bought as its own line. EGGER says an insulation underlay goes on top of its moisture film, Kährs says floating floors require one, Quick-Step says to always use its own underlay, and Woodpecker advises one with a built-in damp proof membrane for most installations. Click vinyl: no extra underlay where Amtico’s Click Smart has its integral one or Quick-Step’s vinyl has underlay attached. Karndean says a separate underlay is not normally advised. Read the pack before adding one.

A moisture layer on a concrete floor

A moisture layer on a concrete floor: what the makers’ installation guides say
Maker	What the maker says
Laminate
EGGER	A moisture protection film with an SD value over 75 m goes over the whole surface as a vapour barrier on a mineral subfloor. It is not needed with a 2-in-1 underlay with built-in moisture protection.
Quick-Step	The vapour barrier comes with the underlay, with its joins taped. Its moisture limits for cement screed are under 2.5 CM% (75% relative humidity) unheated and under 1.5 CM% (65%) heated.
Click vinyl (rigid core)
Amtico	It names no membrane. The floor can be installed on a damp subfloor at up to 95% relative humidity.
Karndean	It names no membrane. The subfloor should read under 95% relative humidity on a hygrometer test.
Quick-Step	It names no separate vapour barrier. Its moisture limits are the same as for its laminate, including 75% relative humidity unheated. If the moisture is over them, consult the subfloor maker for damp proofing.
Glue-down vinyl
Amtico	Says the subfloor is dry at 75% relative humidity or below. Above that, it says a surface damp proof membrane can go on, or the subfloor can be left longer to dry.
Karndean	Under 75% relative humidity on a hygrometer, or no more than 2% CM on cement screed. Above that, it says a damp proof membrane or moisture suppression system “must be used”.
Engineered wood
Kährs	Says a mineral subfloor such as concrete requires a vapour barrier under the wood floor.
Quick-Step	The underlay’s joins are taped to give a sufficient damp-proof layer. The moisture limits are the same as for its laminate.
Woodpecker (Harlech)	Readings should not exceed 70% relative humidity for cement-based concrete.

Sources. All read on 29 September 2026. A date in a link's words is printed on the document, except where the words say it comes from a document code or a file name: Amtico Click Smart installation guidelines, March 2023 (from the document code ACS-IN-20230314); Amtico LVT installation guidelines, February 2025 (from the document code DES-IN-20250218); EGGER Flooring Collection 25+ installation instruction, edition 09/2024 (from the document code printed at its end); Kährs UK questions page; Karndean rigid core installation guidelines, January 2024; Karndean Gluedown installation guidelines, November 2023; Quick-Step laminate installation guide, version 07.2026; Quick-Step rigid click vinyl installation guide, version 07.2026; Quick-Step wood flooring installation guide, version 07.2026; Woodpecker Harlech installation instructions, no date printed (the file name says version 21 and the address says April 2025).

On your list: On concrete, EGGER and Quick-Step name a vapour barrier or a moisture film for laminate, and Kährs and Quick-Step name one for wood on a mineral subfloor. Woodpecker advises an underlay with a built-in damp proof membrane for most installations, and gives a limit of 70% relative humidity. For glue-down vinyl, Amtico says a surface damp proof membrane can be applied above 75% relative humidity, and that the subfloor can instead be given time to dry. Karndean says a damp proof membrane or moisture suppression system must be used above its limits, which are 75% relative humidity or 2% CM on cement screed. Click vinyl: neither Amtico nor Karndean names a membrane, and both allow up to 95%, while Quick-Step’s limit is 75%. The guide on underlay and damp-proof membranes says what to check first.

The expansion gap

The expansion gap: what the makers’ installation guides say, by floor
Maker	What the maker says
Laminate
EGGER	At least 8 to 10 mm at the edges. Its guiding formula is 1.5 mm per metre of floor surface.
Quick-Step	1 mm per metre of floor width, and at least 8 mm. Floating up to 13 m by 13 m.
Click vinyl (rigid core)
Amtico	At least 5 mm for rooms up to 10 m long. 10 mm is advised for rooms over 10 m long, in direct sun, or with temperature swings.
Karndean	At least 5 mm round the room and every fixed object including pipes. 8 mm for areas over 100 m². At least 10 mm in rooms with large temperature swings.
Quick-Step	8 mm round the whole edge of the floor, and round every fixed object and pipe.
Engineered wood
Kährs	At least 10 mm at doorways and round the room, for floating floors.
Quick-Step	Floating: 1 mm per metre of floor width, and at least 8 mm. Glued down: 5 mm round the edge.
Woodpecker (Harlech)	2 mm for every metre span of the floor, and at least 10 to 15 mm.

On your list: The gap is set by the maker, the floor and the size of the room. The rates are not on the same footing: 1.5 mm per metre of floor surface (EGGER), 1 mm per metre of floor width (Quick-Step) and 2 mm for every metre span of the floor (Woodpecker). The minimums run from 5 mm to 15 mm. Read the gap in your floor’s own guide before you buy spacers.

Extra to order

Extra to order for cuts and waste: what the makers say, by floor
Maker	What the maker says
Laminate
EGGER	At least 10% surplus, and perhaps 15% for patterned or tile-effect boards. The same blog passage says spare boards are a good backup, and can replace damaged boards later.
Quick-Step	Its questions page says 5% extra for a regular room and 10% for a room with many angles and curves. Its laminate product page says 10% extra to make up for cutting loss.
Click vinyl (rigid core)
Amtico (Click Smart Parquet)	At least 15% for rooms under 10 m², and 10% for larger areas. Narrow or awkward spaces may need more.
Quick-Step	10% extra to make up for cutting loss.
Engineered wood
Kährs	About 5%, which covers cutting, pattern matching and future repairs. 7 to 10% for herringbone, chevron and stairs.
Woodpecker	Its guide to how much flooring to order says about 10 to 15% for offcuts and pattern matching, and that herringbone needs more than a plank floor. Its Harlech product page says it generally advises 10%, and to check with your installer.

Sources. All read on 29 September 2026. A date in a link's words is printed on the document, except where the words say it comes from a document code or a file name: Amtico Click Smart Parquet installation guidelines, March 2023 (from the document code ACSP-IN-20230314); EGGER UK blog, how to lay laminate flooring; Kährs UK questions page; Quick-Step questions page, how much floor do I need; Quick-Step laminate product page; Quick-Step vinyl product page; Woodpecker, how much flooring do I need; Woodpecker Harlech product page.

On your list: Most makers here say about 10%. The range runs from 5% to 15%, and more for awkward rooms and patterns. The figures are not all for the same thing. EGGER’s blog gives its 10% beside advice to keep spare boards for later repairs, and Kährs says its 5% includes future repairs, while Quick-Step and Woodpecker name cutting loss, or offcuts and pattern matching. So they are not all like for like. BuildBatch starts at 10% and lets you change it. See wastage allowance explained for what the allowance is for.

What this does not tell you

Which floor to buy. Durability, look, sound, feel underfoot and how a floor wears are only settled by a test. None has been done for this page.
Everything a guide covers. Makers also give a time to acclimatise the boards, a limit on how flat the subfloor must be, rules for underfloor heating, and where the floor may go in a bathroom. They differ, and they are not compared here.
Your floor. The guide for the exact floor you buy comes first. A maker’s guide can change between editions.
Prices. They are left out on purpose.

Do it with BuildBatch

Open the Room Refresh Batch with flooring chosen, say what the floor is going onto and how it is fitted, and the underlay and moisture layer lines change to match. Type the extra to order from the pack’s own guidance.