Doormat and entry runner sizes

Doormats are bought by eye and fitted by hope, and the two failures that follow are always the same: the mat is narrower than the stride that crosses it, or it is thicker than the gap under the door. Both are measurable before anything is bought, and one of them cannot be fixed afterwards.

Two jobs, and why one mat cannot do both#

A mat at an entrance is asked to scrape and to absorb, and the constructions that do each are different enough that a mat which is good at one is poor at the other. Coir, rubber link and aluminium grid mats have an aggressive surface and open structure, so they knock grit off a sole and let it fall through, and they hold almost no water. Cotton, microfibre and needle-punch nylon hold water at roughly half a litre per square metre of mat, and clog with grit until they stop scraping at all.

That is the whole argument for the two-mat system: a scraper outside, an absorber inside. The dimensions differ too. The outside mat wants to be wide, because people step off a threshold at an angle. The inside mat wants to be deep, because water leaves a shoe over the first two or three steps.

The measurement that decides everything#

Before a size, measure the gap under the door at the point of maximum swing. Close the door, slide a folded tape or a coin under the leading edge, then open it to 45 degrees and check again in the middle of the arc: floors are rarely flat, and a door that clears at the closed position often fouls a third of the way round. That number, minus 1/8 in (3 mm) for the leaf dropping on its hinges over time, is the maximum total build-up of mat plus pad that can live inside the swing.

The datum for the mat's own thickness is the compressed height under a person, not the loft it has in the shop. A coir mat nominally 3/4 in (19 mm) thick measures about 5/8 in (16 mm) with a foot on it. That is still more than most inward-opening entrance doors will clear.

Interior doors are normally hung with 1/2 to 3/4 in (13 to 19 mm) of clearance over a finished floor, so a hall runner is usually safe. Entrance doors are not: between the threshold, the weather seal and a draught excluder, an inward-opening front door frequently has nothing to give at all. Where a coir mat is wanted, the answer is a recessed matwell 3/4 to 1 in (19 to 25 mm) deep, set out with the flooring rather than after it, and the build-up arithmetic is the same as in floor transitions and threshold heights.

Outside mat sizes#

Width is the dimension that decides whether the mat is used, because a person arriving at a door is turning as they step. A mat narrower than the leaf lets one foot land on the floor beside it every single time.

Depth follows the step, not the door. An adult step length is 28 to 30 in (71 to 76 cm) at a walking pace, so a mat 30 in (76 cm) deep buys exactly one footfall and a 24 in (61 cm) mat buys slightly less than one. Anything under 18 in (46 cm) deep is decoration.

Two things constrain the outside mat that the inside one escapes. The first is the landing: the IRC requires a landing at an exterior door at least as wide as the door and 36 in (91 cm) deep in the direction of travel, and a 30 in deep mat on a 36 in landing leaves 6 in (15 cm) of bare landing, which is tight for standing while a door opens. The second is the swing of an outward-opening door, which sweeps the entire landing and rules out any loose mat inside the arc. Both are set out in entry door clearances, landings and the approach.

The inside mat, and what it is really catching#

Inside, the job is water and the fine grit that survived the scraper. Depth matters more than width here because the shoe is now travelling in a straight line, so 24 in (61 cm) is the working minimum and 36 in (91 cm) is better if the door swing allows it. Width should still cover the door opening, which for a 36 in (91 cm) leaf means a 36 in mat.

The inside mat almost always sits inside the door's swing, which is what forces it to be thin. A 36 in door swinging over a 3/8 in (10 mm) mat needs 1/2 in (13 mm) of clearance at the leading edge for the whole arc, and the arc is what catches people out: the leaf's outer corner travels on a 36 in radius, so it passes over the far corner of the mat, not the near one. Mark the arc on the floor in pencil before buying anything, using the method in door swing, clearance and approach space.

Runners in the hall beyond#

A runner is the third stage of the same system, and it is sized by the hall rather than by the door.

The border of bare floor is doing real work: it keeps the runner off the skirting, where a rug edge curls, and it gives the eye a line that makes a narrow hall read as wider rather than as a strip of carpet. Below about 4 in (10 cm) each side the effect reverses and the runner looks like failed fitted carpet. The relationship between hall width and how much furniture and floor covering it can carry is worked through in hallway widths that work, and the stocked sizes for every rug format are in standard rug sizes.

Length is set by the door swings along the hall, not by the hall. Measure the clear run between the arc of the entrance door and the arc of the first internal door, then buy the stocked length below it: 6, 8, 10, 12 and 14 ft (183, 244, 305, 366 and 427 cm) are what exists. A runner that ends under a swinging door gets lifted twice a day and will not lie flat again. Under all of it, a 1/8 in (3 mm) felt and rubber pad, sized 1 in (25 mm) smaller than the runner on every edge, as set out in rug pad sizes and thicknesses.

Edges, trip hazards and matwells#

A mat is a change in level, and change in level is the most common trip point in a house. The 2010 ADA Standards allow 1/4 in (6 mm) of vertical change with no treatment, and between 1/4 and 1/2 in (6 and 13 mm) the edge must be bevelled at no steeper than 1 in 2. Above 1/2 in (13 mm) it becomes a ramp. A 3/4 in (19 mm) coir mat laid on a finished floor is three times the untreated limit at every edge, which is the technical version of what everyone already knows about coir mats and toes.

Three ways out, in order of cost:

1. Go thin. A 1/4 in (6 mm) flat-woven mat is inside the untreated limit on all four edges and needs nothing done to it.
2. Bevel. A moulded rubber mat with a tapered edge at 1 in 2 or shallower is compliant up to 1/2 in (13 mm) of thickness.
3. Recess. A matwell formed in the screed or the subfloor to the mat's compressed thickness brings the top of the mat flush with the floor, and takes any construction you like. It has to be set out before the floor goes down, and the well is sized 1/4 in (6 mm) larger than the mat on each side.

Where the entry has to work for a wheelchair or a walking frame, the pile depth matters as well as the edge: the ADA limits carpet pile on an accessible route to 1/2 in (13 mm), and a loose mat with an unsecured edge fails regardless of its thickness. The approach and manoeuvring space that goes with it is covered in accessible door widths, hardware and approach.

Sizing the whole sequence#

Treat the three pieces as one system and the sizes fall out in order: an outside scraper as wide as the leaf plus 6 in (15 cm) and 30 in (76 cm) deep, an inside absorber the width of the opening and 24 in (61 cm) deep, and a runner sized to the hall with 4 to 6 in (10 to 15 cm) of floor each side. In a mudroom the same sequence stretches: the drying zone replaces the inside mat, and the numbers for that are in mudroom sizes and layouts.

Where the entry opens straight into a living space rather than a hall, the inside mat has to negotiate with an area rug instead of a runner, and the two should not touch: leave at least 12 in (30 cm) of bare floor between them so the edges are read as separate objects. Rug placement in that situation follows living room rug sizes and placement, and the rug size calculator will size the larger rug once the entry route across it is known. The rest of the entry sequence, from the approach to the drop zone, is set out across the entryway section.