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Carpet on stairs, elevator cabs and floor transitions: the rules and the care
Stair treads, elevator cabs and the edges where carpet meets another floor are crossed by nearly everyone who enters. Here are the installation and ADA rules behind them and how their cleaning differs.
Small areas that carry the whole building
A flight of stairs, an elevator cab or the strip where a corridor’s carpet meets a vinyl lobby adds up to a sliver of a building’s floor area, yet nearly everyone who enters crosses one of them. Every step lands on a tread edge, every cart rolls through the cab, and every visitor steps over the transition on the way in. These are the places a floor shows its age first and the places where installation details and accessibility rules come into play.
This guide gathers the published rules for all three: CRI 104, the carpet industry’s installation standard, and the ADA Standards for stairs, elevators and floor surfaces. It then turns to what carpet warranties say about stairs and how cleaning changes on a step or inside a cab. Installation, re-stretching and repairs are the work of an installer or flooring company; the cleaning side is ours.
How CRI 104 says stair carpet goes down
CRI 104 starts with the stair itself. Treads, risers and the nose must be clean, dry and sound before carpet goes on, and the return of the stair nose should be rounded 3/4 to 1 inch so a sharp edge does not cut the carpet or cushion. Where a separate cushion is used, it extends over the nose.
- Stretch-in stairs: tack strip on each tread with the pins toward the riser; waterfall stairs also get tack strip on the risers
- Cap-and-band (contoured) stairs: no tack strip on the risers
- Glue-down stairs with a nose return: tread and riser as separate pieces; stairs without a return can be one piece
- Direction: machine direction along the length of the stair, and most makers want the pile running down the stairs
- Edges: exposed edges edge-sealed and seams sealed
Those details matter later, during cleaning. A sealed edge holds up to brushing and extraction; an unsealed or loose one frays faster with every pass. When crews find a nosing lifting or a seam opening on a step, the fix is a call to the installer, and the cleaning plan works around that tread until it is repaired.
What the ADA asks of stair treads
The ADA Standards treat stairs on their own terms in section 504. The radius of a tread’s leading edge can be no more than 1/2 inch, nosings can project no more than 1 1/2 inches, and risers can slope under the tread at up to 30 degrees. Treads must meet the floor surface rules of section 302 with no changes in level, at a slope no steeper than 1:48. Treads and landings exposed to wet conditions must be designed to keep water from pooling, and the advisory notes suggest visual contrast on nosings.
Keep the two numbers apart. CRI 104’s 3/4 to 1 inch rounding is an installation instruction about preparing the stair nose so it does not cut the carpet. The ADA’s 1/2 inch is a maximum radius for the finished tread’s leading edge. They come from different documents written for different purposes, and a stair project has to answer to each one separately.
Elevator cabs: the same floor rules in a smaller box
For elevator cars, ADA section 407.4.2 (repeated in 408.4.2 and 409.4.2 for other lift types) says the car floor must meet sections 302 and 303. Carpet in a cab therefore follows the same rules as carpet in a corridor: fastened down securely, with either no cushion or a firm cushion, pad or backing, a level loop, textured loop, level cut pile or level cut/uncut pile texture, a pile no higher than 1/2 inch and every exposed edge fastened with trim. The gap between the car sill and the landing sill can be no more than 1 1/4 inches.
No published standard sets a cleaning routine for cab carpet, so the plan comes from how the cab is used. In a hotel or conference center the cab carries luggage carts, catering trolleys and event crowds, which grinds soil into a small area fast. Cleaning it means working with the building to take a car out of service during a quiet window, protecting the sill and walls, and leaving the floor ready before the car returns to the rotation.
Transitions where carpet meets another floor
CRI 104 says carpet edges that meet another floor should be protected by a transition molding. Where there is no molding, the hard-surface edge should sit no more than 1/16 inch above the total thickness of the carpet, and broadloom edges get a bead of seam sealer at least 1/8 inch wide. On the ADA side, section 303 allows a change in level of up to 1/4 inch to be vertical, requires a bevel no steeper than 1:2 between 1/4 and 1/2 inch, and calls for a ramp above 1/2 inch.
For cleaning, the transition is where carpet takes grit and residue straight off the neighboring floor. Crews treat that first strip of carpet as its own zone, check that the molding still holds the edge and report any lifting or raveling for the installer to address.
What carpet warranties say about stairs
Manufacturers single stairs out. Milliken’s hospitality warranty package gives lifetime wear coverage on its carpet but caps stair wear coverage at a 5-year term, and a 2016 Milliken warranty document gives 5-year wear coverage on stairs and 10-year coverage for modular carpet installed with a nosing. Interface lists stairs among its warranty exclusions, and Shaw’s 10-year commercial broadloom warranty excludes stairs too. Each manufacturer and product carries its own terms, so read the maintenance and exclusions sections of your own document before you plan the stair carpet’s care.
Stair edges also collect a soil pattern of their own. CRI’s filtration soiling bulletin describes dark gray lines that form at stair edges, beneath doors and along walls, caused by air pulling airborne soil through the carpet. CRI does not treat it as a defect or a sign of poor carpet quality, and it is worth pointing out at the walkthrough so those edges get their own attention in the plan.
Cleaning stairs and cabs around a working building
Stairs get cleaned one tread at a time, with tools sized for a narrow surface and steady attention to the nose and to the edge lines along the wall. OSHA’s walking-working surfaces rule asks that floors be kept free of hazards such as spills, so crews sign each flight, keep cords and hoses clear of the path and leave every stair dry before it reopens. Interim passes keep treads presentable between visits, and hot-water extraction restores them on the deep cleaning schedule.
We schedule stairwells and cabs in the evenings, on weekends or between events, and pair them with traffic lane restoration on the landings and corridors they feed. Spot and stain removal handles drips and edge lines between visits. For hotels and event spaces, the free walkthrough maps each flight, cab and transition, and the written quote sets a method and a time window for each one. Book a walkthrough to put your stairs and cabs on the plan.
A few useful answers
Common questions.
Who fixes a loose stair nosing or carpet lifting on a step?
An installer or flooring company. CRI 104 calls for stair carpet edges and seams to be sealed and fastened at installation, so a loose nosing is an installation repair. Our crews flag it during a visit and clean around that tread until it is fixed.
How rounded can a carpeted stair edge be under the ADA?
ADA section 504.5 caps the radius of a tread’s leading edge at 1/2 inch and the nosing projection at 1 1/2 inches. CRI 104’s 3/4 to 1 inch rounding is a separate installation instruction for preparing the stair nose so it does not cut the carpet.
Does a carpet warranty cover the stairs?
Each document answers differently. Milliken’s hospitality package caps stair wear coverage at a 5-year term, Interface lists stairs among its exclusions, and Shaw’s 10-year broadloom warranty excludes stairs. Check the exclusions section of your own warranty.
Can elevator carpet be plusher than the corridor carpet?
No. ADA section 407.4.2 applies the same floor surface rules to elevator cars as to other floors, so cab carpet keeps a pile of 1/2 inch or less, a firm backing or cushion and trimmed, fastened edges.
Can stairs be cleaned while the building stays open?
Yes, with planning. We clean in the evenings, on weekends or between events, sign each flight while it is being worked and reopen it only once it is dry, so staff and guests keep a clear route.