Fixing methods for wood floors: which is allowed where

At a glance

Each cell is what a document says, not permission: the maker’s instructions for the exact product decide. D: UK distributor (2022 to 2024). M1, M2: one UK timber floor maker (2024, 2017). M3: a solid hardwood maker (2022). N: NWFA, US (2016).

Four methods, drawn

Four ways of holding a wood floor down are in common use, and the drawing shows each in section. Fully bonded floors are adhered over their whole back to the base, so the floor follows the base. Floating floors are fixed to each other, by glued or click joints, and laid on an underlay, so the whole floor moves as one sheet and a gap is left at every wall. Secret-nailed floors are nailed at an angle through the tongue, hiding the nail, into joists, battens or a deck; the first and last rows are usually face-nailed where a blind nailer cannot reach (NWFA). Glued and nailed floors do both, which the distributor asks for on wide engineered boards.

No document we read gives a general rule saying which method a given floor may use. Each says, in effect, follow the instructions for the product, and several name BS 8201:2011, the British code of practice for installing wood and wood-based flooring, as the standard they complement. We read BSI’s listing for it (current, published 31 October 2011) but not the text, so the matrix below rests on the makers’ and distributor’s documents, and on one US trade association’s guidelines, not on the standard.

What the documents allow, floor by floor

The table at the top of the page gives the short version. Three points sit behind it.

• The format decides most of it. Patterns are bonded. One maker says chevron, Versailles and other parquet patterns must be bonded whatever the joint, unless it advises otherwise for the project, but that a click herringbone may be floated. The distributor’s parquet guideline covers bonding, with pins, and does not mention floating. End-grain blocks ‘must be fully bonded’. Our own installation guide is stricter than that maker: it asks for bonded patterns and does not float parquet patterns at all.
• Width limits nailing. The distributor secret-nails engineered boards 140 mm wide or under on their own and asks for glue as well as nails above that. One maker suggests a maximum width of 180 mm for nailing, and says wider boards may need face fixing or glue and nails. Our installation guide puts the line for bonding at 250 mm: that is wider than both.
• Underfloor heating is where the sources part company. One maker says tongue-and-groove floors in every format must be fully bonded over underfloor heating, that only click-profile planks may be floated, and that its solid floors are not suitable. The NWFA lists floating engineered floors, and solid or engineered boards nailed to a wood base, among the methods that can be used successfully over radiant heat, with the manufacturer’s instructions to be followed. A solid-floor maker publishes a batten system in which solid boards are nailed over heat-distribution plates. These do not contradict each other, because each is product- or system-specific, but they show why ‘can I nail solid wood over heating?’ has no general answer. See underfloor heating under wood and stone.

Key: D, a UK flooring distributor’s guidelines (November 2022 to January 2024); M1, a UK timber floor maker’s floating floor guide (28 March 2024); M2, the same maker’s nail-down guide (23 October 2017); M3, a solid hardwood floor maker’s batten sheet (8 March 2022); N, the US National Wood Flooring Association’s Installation Guidelines (revised February 2016). A distributor is not an independent trade body, and the NWFA’s guidance is for US practice. A cell is what a document says, not permission: the instructions for the exact product decide.

The base, the heating and the acoustic layer

The method also has to suit the base. Floors fail most often from moisture and flatness, so the documents repeat the same checks whatever the method. The table gathers what they say about each base and layer; the figures are theirs, and where documents differ the page says so. For the moisture and flatness checks in full, see subfloor requirements for wood flooring, and for sound, acoustics for wood floors, which explains why a floating floor on a resilient layer is also an acoustic build-up.

What the method does to movement

The fixing method changes how the floor moves, and so what the details must do.

• Gaps. The documents give different figures, so the specification should state one and say which document it follows.

• A floating floor moves as one sheet. The maker’s guide says kitchens and other fixed furniture or joinery should not be placed over a floating floor: build them first and fit the floor up to them. If a unit must be fixed over a floated floor, the weight should be carried by the walls or by feet on the base, and each fixing point over-drilled by at least 20 mm with room for movement on all sides. A threshold bonded to the flooring may be bonded to one side only, and one fixed to the base needs a gap each side of the fixing.
• Nailed floors. Nail spacing is given as 200 to 250 mm, not within 50 mm of a board end, with nails at least two and a half times the board thickness (maker); about 300 to 400 mm and 100 mm from each end on plywood, and on every joist (distributor); and 6 to 8 in (about 150 to 200 mm) for blind-nailed solid strip (NWFA). The maker adds that mechanical nail guns can tighten boards together, so a pneumatic gun is suggested where intermediate gaps are needed.
• Bonded floors. Adhesive, trowel notch and open time are the adhesive maker’s; the distributor says the most critical time is during, and for 48 hours after, installation, because a change in temperature or humidity can lift boards from the adhesive.

Questions for the partner

Fixing method drives the warranty, so put the question to the partner in writing before the method is fixed in a drawing or a quotation:

• Which fixing methods does the maker’s own instruction sheet allow for this exact product, thickness and width, on this base?
• Is underfloor heating present, and is the method approved for it by the maker in writing?
• If floating: which underlay, which vapour layer, which joint, and what gap at walls and obstructions?
• If nailed: nail type, length and spacing, and any limit on board width.
• Does the warranty wording name the fixing method, and what does it say if another is used?

Floor: [product, width, thickness], fixed [fully bonded] to [primed cement screed / ply overlay of [ ] mm] using the flexible adhesive and notched trowel stated in the floor maker’s installation instructions [ref, date]. The partner shall confirm in writing, before order, that this method is covered by the product warranty [over underfloor heating: yes / no]. Perimeter gap [ ] mm, covered by skirting or scotia.

Floating installation only where the maker’s instructions for [product] allow it: [click / glued tongue-and-groove] joints, underlay [ref] with a sealed vapour layer, perimeter gap [12 / 15] mm, no joinery fixed through the floor. Any fixing through the floor to be over-drilled by [20] mm on all sides with the load taken by the base.

Boards [secret-nailed] through the tongue to [joists at [ ] mm centres / [18] mm ply deck], nails [ ] mm at [ ] mm centres, building paper lapped [100] mm over joists. Board width not to exceed [140] mm unless glued and nailed. Moisture content of the base [ ]% and of the boards [ ]% recorded before fixing.

Standards and sources

• BS 8201:2011 Code of practice for installation of flooring of wood and wood-based panels: Current, published 31 Oct 2011, per BSI listing; descriptors include floating floors, underfloor heating and fixing. Text not read.
• BS EN 314-1:2004 plywood bonding quality; BS 8204-1:2003+A1:2009 screeds: cited by the distributor and the maker; Current on BSI Knowledge, 6 Nov 2026. Named, not read.
• Installation guides: a UK flooring distributor (parquet, plank glue down, plank secret nailed, end grain, 2022 to 2024); a UK timber floor maker (floating 2024, nail down 2017); a solid hardwood maker (battens with underfloor heating, 2022); NWFA Installation Guidelines (US, revised 2016): read in full, 6 Nov 2026.

Questions we are asked

Can herringbone or chevron flooring be floated?

It depends on the product. One UK maker says chevron, Versailles and other parquet patterns must be bonded whatever the joint type unless it advises otherwise for the project, but that a click-joint herringbone may be floated or bonded. The distributor’s parquet guideline covers bonding with pins and does not mention floating. Our own installation guide does not float patterned floors. Ask the partner for the maker’s written position on the exact product.

Can solid wood be nailed down over underfloor heating?

The documents differ. One maker says its solid floors are not suitable over underfloor heating. The NWFA lists direct nailing of solid or engineered boards to a wood base among the methods that can work over radiant heat, with the manufacturer’s instructions to be followed. A solid hardwood maker publishes a batten system with heat-distribution plates. Get the maker’s approval of the exact system in writing.

Can a kitchen or fixed unit stand on a floating floor?

The maker’s guide says not: fixed furniture and joinery should be built first and the floor fitted up to them. If a unit must be fixed over a floated floor, its load should go to the walls or to feet on the base, with each fixing over-drilled by at least 20 mm.

Does a floating floor need an underlay?

Yes, unless the product has one attached. The maker’s guide says underlays differ in acoustic performance and in isolating moisture, that foil-backed underlays need taped joints, and that a vapour barrier is not a damp-proof membrane.

How wide can a board be if it is nailed?

The distributor secret-nails engineered boards of 140 mm or under on their own and asks for glue as well as nails above that. One maker suggests a maximum of 180 mm for nailing, with wider boards needing face fixing or glue and nails. Confirm the limit for the product.

Does the fixing method affect the warranty?

The documents we read do not give warranty terms, and the maker’s sheets say the final responsibility for installation lies with the installer. Ask for the warranty wording and have it name the fixing method and any underfloor heating.