Fieldnotes
The hardest floor in the building, and the four decisions that determine whether it looks right in ten years.
A stair asks more of a carpet than any other surface in a building. It is the one place where the goods are bent hard, walked on at the bend, seen from below at eye level, and required to turn a corner onto a landing without the pattern giving the game away. It is also the place where a specification decision made casually is most expensive to undo, because a stair cannot be relaid without stripping the whole flight.
Most of what follows is not complicated. It is simply rarely written down.
Every step is a horizontal tread, a vertical riser, and a nosing where the two meet. The tread takes the traffic. The riser is the surface a person actually looks at, because it sits at eye height as they climb. The nosing takes the load of both and holds the carpet through roughly ninety degrees of turn.
Those three surfaces have completely different requirements, and the carpet has to satisfy all of them in one continuous piece of goods. That is the whole problem in a sentence.
The nosing is the reason. Fold a carpet over a stair edge and the pile on the outside of the fold opens up: the tufts splay apart and whatever holds them becomes visible and load-bearing. Every foot that climbs the flight lands within an inch or two of that fold.
In a woven carpet the pile is interlaced with the warp and weft as the cloth is made, so the structure at the nosing is mechanical. In a tufted carpet those tufts are held by a secondary backing and an adhesive. Both can be installed well, but a stair tests the difference soonest, which is why woven goods have historically been the default on a principal stair.
Pile type matters at the nosing too. A tight loop or a low combination cut and loop tends to hold its face over an edge better than a tall cut pile, which splays more visibly. Fieldmark's Karaloc constructions run a close 0.180″ pile, which behaves well on a fold; the full-pitch Wire Wiltons at 0.250″ loop are the next most forgiving. A 0.290″ Axminster cut pile is a beautiful stair carpet and asks more of the installer at the nosing.
This is the decision most often made last and it should be made first.
A stair is a fixed rhythm. American residential risers run roughly seven inches and treads roughly eleven, so each step consumes something in the order of eighteen inches of goods. That rhythm repeats up the flight regardless of what the pattern is doing.
Now put a pattern against it. Agate's repeat is 78.74″ × 81.97″. At eighteen inches a step, one repeat spans four and a half steps, so the pattern lands in a different place on every tread until the fifth. Unless the drawing has been set out deliberately against the stair, that reads as an accident rather than a decision.
At the other end, Hybrid repeats at 5.14″ × 5″. Three repeats fit on a single riser. The pattern effectively becomes a texture and the stair rhythm never conflicts with it. Guillo at 36.05″ × 29.81″ sits in between: two steps to a repeat, which can be set out to work but has to be set out.
The rule is a simple one. The smaller the repeat relative to the step, the less the stair has to be planned around the pattern. A large repeat is not disqualified, but it converts the stair from an installation into a drawing exercise, and that drawing has to be done before the goods are cut.
The question to ask the mill
Where should one repeat land on the flight, and does the pattern read the same on the riser as it does on the tread? On a large repeat, ask for the stair to be set out on paper against the actual riser and tread dimensions before anything is ordered. It is a half-day of work that prevents the single most common regret on a specified stair.
Carpet has a direction. The pile lies one way, and it reads lighter or darker depending on which way you view it. On a flat floor that is a subtlety. On a stair, where you look up at every riser in the flight, it is not.
Stair carpet is conventionally laid so the pile lies down the flight, running with the descent. It wears better that way, because footfall pushes with the pile rather than against it, and it reads consistently from the bottom of the stair, which is where people stand and look. Pattern direction has to be resolved at the same time: if a design has an obvious top and bottom, decide which way it faces going up before the cutting plan is made.
The consequence for the cut plan is real. A stair run is cut lengthwise from the roll so that no seam falls on a tread, and running direction is then fixed for the whole flight. If the landing is to match, it has to be cut with the same orientation, which uses more material than laying it the economical way. Decide this early and price it in.
The landing is where the specification usually falls apart, because it is where two decisions collide: the pattern turns ninety degrees, and a seam has to go somewhere.
Three things to settle in the drawing.
The stair is the dirtiest floor in a house, because everything from outside travels up it. Wool helps as a matter of fiber rather than specification: it hides soil rather than displaying it, and its crimp lifts the pile back out of the walking line between cleans. Even so, a mid-tone or broken colourway holds its appearance on a stair longer than a flat pale one.
And whichever construction is chosen, order the stair and the adjoining floors from the same production run. Fieldmark weaves to order and holds no stock, which means a later addition is a later run, and a later run is a different dye lot. If a stair, a landing and a corridor are meant to read as one floor, they need to be woven as one order.