Binding holds up better than serging on a stair runner, and the reason is mechanical: binding folds a woven tape over the cut edge so the tape lies flat against the carpet, while serging wraps the edge in yarn that stands proud of the pile and meets every shoe and vacuum wheel first. On a rug in a bedroom, either one will outlive the carpet under it. Stairs are a harder test. The edge gets stepped on, dragged across and bent around the nose of every tread, and the finish you pick either survives that or shows it.
What Is Carpet Binding?
Carpet binding wraps a cut carpet edge in a strip of woven tape, stitched down so it covers the raw edge and a little of the face on both sides. Width changes the look. A narrow tape reads as a clean line; a wide one reads as a border, which is what most people mean when they say they want a rug that looks finished. The tape is woven from cotton or from a synthetic yarn. Cotton has a soft texture that suits a wool rug, and synthetic shrugs off stains better, which is what you want on an edge people walk over. Either way the tape's own edge is finished at the mill, so it can't fray once it is sewn on.
Binding is what you have seen on most finished area rugs, and it is work we do ourselves: our area rug binding, carpet binding and custom rug work turns broadloom (carpet off the roll) and remnants into rugs with a finished edge. If your piece will lie flat on a floor instead of running down a staircase, our earlier article on how binding and serging compare covers that choice.
What Is Carpet Serging?
Carpet serging finishes the edge with yarn instead of tape. The yarn wraps the edge over and over in a close overcast stitch, like the whipped edge of a hand-knotted Oriental rug, and Stanton, one of the mills we carry, describes it the same way in its glossary: heavy colored yarn sewn around the edge of a rug cut from roll goods. A serged edge is softer and rounder than a bound one. The yarn can match the pile so the edge disappears, or contrast with it so the edge becomes the detail, which is why serging gets picked when the edge is meant to be looked at.
Which Edge Finish Holds Up on Stairs?
Binding is the safer edge finish on stairs, because the tape sits flat and the surface taking the wear is woven fabric rather than a rounded rope of yarn. Serging can work on a runner, and plenty of good-looking staircases are serged. The trade-off is that the yarn takes the abrasion first, and once a serged edge thins out, the repair is re-serging that whole run rather than touching up a tape.
A turned edge is the third option and most homeowners never get offered it. A turned edge is where the carpet is folded under itself instead of being finished with tape or yarn, so nothing is added along the edge at all: no strip of fabric, no band of stitching, just carpet folded back and held out of sight. It gives the cleanest look of the three, and it puts everything on the person installing it, because a turned edge is only ever as straight as the cut and the fold underneath. Ask for it by name if you want it. It is a conversation to have with your installer rather than something you pick off a sample board.
Whichever finish goes on top, the cut edge underneath has to be sealed. The Carpet and Rug Institute is the trade association American carpet manufacturers belong to, and CRI 105 is the installation standard it publishes for carpet in houses, the document most of them point to when they set out how their carpet has to be put down. On stairs it is blunt: any exposed edge has to be edge sealed, upholstery work must show no raw edges, and every seam gets sealed too. Edge sealing is a bead of adhesive worked into the cut edge of the backing so the tufts cannot pull free. It adds a few minutes per edge, and it is the difference between a runner that frays at the second step and one that stays tight.
Binding, Serging and a Turned Edge Compared
Binding, serging and a turned edge solve the same problem three different ways, and which one belongs on your stairs comes down to how much traffic the edge takes and how much you want to notice it.
Edge finish | What it is | On stairs | What drives the price |
|---|---|---|---|
Binding | Woven cotton or synthetic tape sewn over the edge, narrow as a line or wide as a border | Flat wear surface; the tape takes the scuffing | Linear feet of edge, tape width, tape material |
Serging | Heavy yarn wrapped around the edge in a close overcast stitch | Yarn stands proud and abrades first; repaired by re-serging the run | Linear feet of edge, yarn fiber, machine time |
Turned edge | Carpet folded under itself, with the gripper strip and cushion cut about 1 1/2 inches narrower than the carpet | Nothing added at the edge; depends on a clean fold and a straight cut | Installation labor rather than materials |
Why Western New York Stairs Are Harder on a Runner
Stairs in New York can legally be steeper and shallower than the national model code allows, and that changes what a runner has to do. The Residential Code of New York State, published by the state's Department of State and enforced by building departments here, caps the riser at 8 1/4 inches and sets the shallowest legal tread at 9 inches. The model code that states start from, the International Residential Code, stops the riser at 7 3/4 inches and asks for 10 inches of tread. Half an inch of rise and a full inch of tread sound like rounding errors. Across a flight they add up to less flat tread for the runner to lie on and more of every step spent curving over the nose.
Measure several steps rather than one, because they are allowed to differ: within a flight the tallest riser may stand 3/8 inch taller than the shortest, and the treads may vary by that same 3/8 inch. The code also takes its dimensions with carpets, rugs and runners left out, so those numbers describe bare wood and your runner and cushion sit on top of them. An older Buffalo or Amherst staircase was built to whatever its builder used at the time, which is one more reason to measure your own.
The nosing is where a stair runner wears out. A nosing is the lip of the tread that overhangs the riser below it, and New York's code asks for that overhang to measure between 3/4 inch and 1 1/4 inches, with no overhang required at all once the tread reaches 11 inches deep. Shallow treads and projecting noses travel together, so the carpet bends around a curve on every single step. That bending has a name. The Carpet and Rug Institute's Carpet Primer calls it grinning: the backing showing through the face of the carpet, often between two adjoining rows of tufts, with installation over sharp curves such as stair nosings among the listed causes. On a staircase it shows up as a pale line along the front of a tread where the pile has opened.
CRI 105 answers grinning on the carpentry side, before any carpet is involved. It asks for the stair nose return to be rounded to between 3/4 and 1 inch so a sharp edge cannot cut the carpet or the cushion, and for a separate cushion to be carried over the nose instead of stopped behind it. Both are worth asking about when someone quotes your stairs.
Waterfall or Upholstered: How the Install Changes the Edge
Waterfall and upholstered are the two ways a runner meets the step, and they load the edges differently. On a waterfall stair the carpet runs off the nose and drops straight to the next tread, and CRI 105 puts tack strip on the risers as well as the treads for that method, pins pointing down toward the tread. Tack strip is the thin wood strip full of angled pins that grips the carpet's backing along an edge. An upholstered install, which some crews call a Hollywood install, presses the carpet into the back corner of every step so the runner follows the shape of the staircase. It takes longer and leaves a staple line at each tread. CRI 105's rule for an upholstered install runs one line: upholstery work shows no raw edges.
Glue-down stairs follow a different rule. CRI 105 lets a staircase without a nose be covered in one piece over the tread and riser, and calls for the tread and the riser to be cut as separate pieces on stairs that have a nose. More pieces means more cut edges, and every one of them gets sealed before the carpet goes down.
Choosing Carpet and Cushion for a Stair Runner
Carpet headed for a stair runner wants a tight twist and a dense pile. Twist is how hard the yarn is spun before it is heat-set to hold that shape, and the Carpet and Rug Institute's Carpet Primer warns that a low twist or a poorly heat-set yarn in a cut pile carpet tends to mat, tangle and look worn. Density is how tightly the tufts are packed into the backing, and the Primer's point about density is that crushing is what happens when there is too little of it for the traffic. Fiber is the third piece: the Primer lists nylon as durable, resilient and abrasion-resistant, which is why the nylon carpet we stock is where most of our stair conversations start.
The cushion under a runner matters as much as the carpet over it. CRI 105 caps cushion thickness in a house at 7/16 inch, asks that the cushion match what the carpet's own manufacturer recommends, and warns that ignoring that recommendation can void the manufacturer's warranty. Thick and soft feels wonderful in a showroom, and it lets the runner shift as you walk over a nosing. Thin and firm is what holds a runner still.
Read your own warranty before you buy, and read it for the stairs in particular. Terms are written product by product and revised whenever the maker decides to revise them, so the version that matters is the one that comes with the carpet you are buying. Ask for it in writing. Look at what it says about cushion, and at any part of the house where the coverage narrows or stops, because the busiest carpet in a house is usually the flight of stairs.
Questions We Get About Stair Runner Edges
Does a serged edge fray?
A serged edge can wear through where the yarn rubs, and on a staircase it usually shows along the nosing as a thinning stripe rather than a hole. What protects the carpet underneath is the edge sealing CRI 105 calls for. A serged edge over a properly sealed cut keeps its shape long after the yarn shows its miles, and an unsealed one opens up.
Can you bind a carpet remnant into a stair runner?
Yes, and a remnant is one of the cheapest ways to get a finished stair runner. The piece has to be long enough to run the flight with the pile facing the right way, since CRI 105 notes that most manufacturers want the pile running down the stairs, so the length of the runner comes out of the length of the roll. We keep rolls and remnants at the showrooms, and you can look through the carpet we have in stock before you drive over. Bring the width and depth of one tread, the height of one riser and the number of steps, and we can tell you quickly whether a piece will make it.
How wide should a stair runner be?
A stair runner is sized off the tread, with finished wood left showing on each side, so measure the tread before you settle on a width. New York's code sets the staircase itself at a minimum of 36 inches of clear width, and the runner comes in from there by however much wood you want to see. Leave a little extra on both sides if you want a turned edge, since the fold eats some width.
Getting the Edge Right on Your Stairs
The edge finish is the part of a stair runner you look at every day, so it deserves a decision rather than whatever the workroom does by default. Binding for traffic. Serging for an edge that gets looked at more than walked on. A turned edge when you want the runner to read as one clean band. Whichever way you go, the carpet wants a tight twist and a dense pile, the cushion wants to be thin and firm and carried over the nose, and every cut edge wants sealing. When you are ready to price it out, request a free estimate and we will measure the stairs, look at the nosings, and tell you what each finish will do on your flight.
