Borders, frames, medallions and inlays in wood floors

At a glance

Names and most guidance are from NWFA Technical Publication B300 (US, 2015); inch figures are converted. Partner workshops confirm every size.

The parts of a framed floor

A framed floor is a field of pattern with a series of bands round it, ending at the walls. The names are NWFA's (Ornamental Floors, Illustration A, page 3). Apron is the band between the border and the wall, which a designer might call the margin or the frame. Feature strip is a narrow line either side of the border. Corner blocks square the corners of the border. A medallion or inlay is a motif set into the field. For the herringbone, chevron or panel field itself see the parquet pattern atlas and herringbone vs chevron.

Every band has a job. NWFA says to adjust the apron to minimise cuts in the field, to end with equal cuts on opposite sides, and to bring the outside edges of the field and apron to a half or whole repeat of the pattern. A UK installer adds that a border gives a straight reference line, keeps the zigzag edge of a herringbone away from wavy walls, and removes many small awkward cuts around door linings and pipes. In a very narrow hall it can make the space feel slimmer, and then the pattern can run to the skirting from a straight line.

Border corners and sections

NWFA names four corners for an apron (mitred, log cabin or lapped, and the reverse of each) and shows Greek key borders with a corner block, a continuous corner or a radius. We have drawn six that follow a stated rule each, and not drawn a Greek key or a guilloche: ask the workshop for its own border drawings and put those on the layout.

• Borders come in sections. Allow a cutting allowance, typically at least one extra section (NWFA). Some need right- and left-hand sections to flow. A ‘continual flow’ corner needs a V-block in the middle of the run so that the corner takes a whole repeat, so calculate the linear runs in whole repeats.
• Corner blocks free the run. Most borders are designed to be cut at the corner block wherever the pattern falls.
• Dry-lay first. Dry-lay the border round the room, starting with the corners, before the field is fixed. NWFA adds that a dry layout is never used for precise measurement: keep measuring as the floor goes down.
• Contrast, calmly. A border should contrast the field. Use the natural colour of a timber instead of a stain where you can, so the next sanding does not raise a dilemma. Do not frame a complex pattern in a complicated border. Check that species suit each other for movement, colour bleeding and grain.
• Thickness. Check actual, not nominal, sizes. If the border is thinner than the field, the subfloor is built up beneath it; for stone, use cementitious board, dry pack or slurry (NWFA).

How wide? Starting points, worked

We found no standard for border proportions, and no source that ties a width to a room. NWFA says the width should suit the scale of the room, that borders are typically placed 12 inches (305 mm) or more from the wall with the apron between, and that a 12 inch border might not be proportionate in a hallway but can often be reduced in scale. The table shows why, and is our arithmetic on NWFA's figure:

One worked frame shows the apron doing its job. In the 4,000 mm room of the herringbone sheet, a field of five whole repeats (3,182 mm) and a frame of brass, a two-block band and brass leave an apron of 223 mm on each side:

Illustrative sizes and our arithmetic: 4,000 − 3,182 − 2 x 186 = 446, shared between two sides. Replace every figure with your own.

Medallions and inlays set into a laid floor

Medallions and other manufactured inlays follow the floor. NWFA says an inlay is installed after the floor is laid so that it fits, and that its position takes account of walls, vents, openings and furniture and is signed off by the client. The usual method is a template, a plunge router in several passes, a dry fit and a flush bond. The point to put in the specification is the timing: NWFA says to install the inlay as soon as possible after routing, because the field can close up around the opening.

• Position. Relate it to the room's focal points (a fireplace, a door, a ceiling feature), draw it, and have it approved on site. NWFA notes that a laser can align a floor layout to a tray ceiling or a chandelier.
• Thickness. Verify the actual thickness of the medallion, border or feature strip against the field.
• Stone, glass and leather. NWFA does not recommend sanding most stone inserts, and glass and leather are not sanded. A plywood blank stands in during sanding; a stone insert needs room for a transition material (silicone, latex or cork) and is fixed before the final coat.
• Flatness. NWFA calls subfloor flatness critical where there are borders, inlays and patterns: any irregularity shows in the finished floor.

This is marquetry-adjacent work. For what separates parquetry, marquetry and inlay, see our marquetry and metal inlay pages.

Brass and metal strips: the detail

NWFA's guidance for a metal strip in a sanded floor is the closest thing to a standard we found, and it comes from the US, so every inch figure below is converted. Preferred: nonferrous metal about 1/4 inch (6.4 mm) thick. Channel: routed with a bit the same width as the metal, in a flattened floor so the depth is consistent. Fixing: use both adhesive and nails, as the strip will otherwise curl up during sanding. Adhesive: two-part epoxy or moisture-cure urethane, tested on a sample with a sanding test. Pins: the same metal as the strip, in predrilled holes at 9 to 10 inch (230 to 255 mm) intervals, their heads sanded off flush. Level: about 1/32 inch (0.8 mm) below the wood before sanding, so the wood is sanded down to the metal and the metal does not overheat. Epoxy has about a five minute working time, so the strip goes in a section at a time.

Movement. NWFA says wood expands and contracts with humidity, while stone and metal react only to temperature. So the timber moves against the strip and the strip does not. On our arithmetic from the US Forest Products Laboratory's white oak values, a 90 mm block of oak changes in width by about 0.5 mm (quarter-sawn) to 0.9 mm (flat-sawn) for a 3 point change in moisture content, so expect a hairline at the strip when the heating is on. A UK distributor says a floor held at 45 to 65% relative humidity moves least.

Sanding. NWFA: a drum or belt sander dulls on metal and cuts unevenly, so sand small areas with an edger, then a buffer; do not let the edger overheat the metal (it can burn the wood or break the adhesive bond); sand in short bursts; vacuum the filings and clean with a solvent before finishing. A strip that stands proud is routed down below the surface first. Depth. A strip is only as deep as the block that holds it. In a 14 mm block, a strip 6 mm deep with its bed leaves about 6 mm of timber below. In an engineered block with a thin wear layer the channel passes into the core: ask the workshop.

Common mistake: specifying a stainless or steel line in a floor that will be sanded on site, or a strip fixed with adhesive alone. Both are called out in NWFA's guidance.

For finishes, patina and lacquer, see lacquered vs unlacquered brass and copper, which found no independent wear data for lacquer on handled brass, and patination. For where a strip crosses a junction, see floor transitions and movement joints.

Frame to layout drawing [ref]: apron [223] mm of [species, width], brass fillet [3 x 6] mm, border band [180] mm of [two rows of 90 mm blocks, species], brass fillet [3 x 6] mm, then the [herringbone] field. Border corners: [mitred / lapped / corner block] as drawing [ref]; corner blocks [ref]. Field to end on a [whole] repeat at the border. Apron width adjusted to suit the room, cuts equal on opposite sides. At least [one] extra border section supplied. Border thickness [ ] mm to match the field.

Strip [3 x 6] mm, [alloy per metal schedule ref], nonferrous, set flush in a channel routed to the strip width, bonded with [two-part epoxy / moisture-cure urethane] and pinned with pins of the same metal at [230 to 255] mm centres, strip [0.8] mm below the surface before final sanding, pin heads sanded flush. Finish [bright / satin / brushed / patinated, ref]. A sample including a sanding test approved before production.

[Medallion, diameter [ ] mm, timbers [ ]] from the workshop drawing [ref], centred on [reference], position approved on site before routing. Installed after the surrounding floor is laid, within [ ] hours of routing the opening. Thickness [ ] mm to match the field. [Stone, glass or leather: plywood blank in place during sanding.]

Sanding sequence agreed on the approved sample. Metal and small areas of changing grain sanded with an edger and buffer, not a drum or belt sander, with heat on the metal controlled and filings removed. Finish [oil / lacquer, ref] confirmed compatible with every timber and metal on the sample, applied by [roller].

Standards and sources

• NWFA Technical Publication No. B300, Ornamental Floors: Design & Installation (3rd edition, 2015): read: layout, borders, inlays, metals, sanding.
• NWFA Installation Guidelines, Chapter 7 (revised 02.2016): read: working lines and layout.
• A UK distributor's guidelines (Jan 2024) and one UK supplier guide (2018): read: perimeter border sequence.
• BS 8201:2011: named; not read. Check against the current edition.

Questions we are asked

How wide should a wood floor border be?

We found no standard and no source tying a width to a room. NWFA says the width should suit the scale of the room and that borders are typically placed 12 inches (305 mm) or more from the wall, though a 12 inch border might not be proportionate in a hallway. On that figure two 305 mm bands take 20% of a 3 m room and 51% of a 1.2 m hall. Draw it and look.

Should the border contrast with the field?

NWFA says yes: a border should contrast the field, preferably in the natural colours of the timbers instead of a stain, so the next sanding does not raise a dilemma. It also says not to frame a complex parquet pattern with a complicated border.

Can I put a brass inlay line in a wood floor?

Yes. NWFA prefers nonferrous metal about 1/4 inch (6.4 mm) thick, bonded with epoxy or moisture-cure urethane and pinned, set about 1/32 inch (0.8 mm) below the surface before the last sanding. Strips of 1 to 3 mm width are usual in furniture; a floor strip is a detail for the workshop to draw.

Can stainless steel be inlaid in a wood floor?

NWFA advises against steel and stainless steel in floors that are sanded on site, because of sparks. Brass, copper and aluminium are the metals it describes. For a prefinished floor, ask the workshop.

When is a medallion fitted?

After the surrounding floor is laid, so it fits, and as soon as possible after the opening is routed, because the field can close up around the hole (NWFA). Its position is approved on site beforehand.

Will a brass strip show a gap?

Timber moves with humidity and metal with temperature, so a hairline can open at the strip when the air is dry. On our arithmetic a 90 mm oak block moves about 0.5 to 0.9 mm for a 3 point change in moisture content. A positive bond, a sound subfloor and a steady 45 to 65% relative humidity keep it small.