Steel is fabricated in a shop and arrives finished. Timber is milled to a tolerance and can be sanded. Brick is fired, sorted, and rejected before it reaches site. Concrete is made in the position it will occupy forever, by whoever is on shift, in whatever weather that day brings.
That is the whole difficulty and the whole appeal. Fair-faced concrete is the only common structural material where the finish is a permanent record of the process, and where the process is a construction activity rather than a manufacturing one.
The finish is the formwork
Architects describe concrete finishes as if they were properties of concrete. They are properties of plywood.
A board-marked wall is a decision about board width, board direction, and how many pours each sheet will be used for. A sheet used once gives a crisp, slightly open grain. The same sheet on its fourth pour gives a smoother, duller surface, because the release agent and the previous pours have sealed the face. On a tall wall built with rotating formwork, the bottom lifts and the top lifts can come from panels at different stages of their working life, and the wall will show it as a subtle horizontal banding that no drawing predicted.
The practices that get consistent results do one of two things: they specify the number of uses per panel and pay for the waste, or they design a pattern that accepts the variation and makes it read as intentional. Both work. Hoping for uniformity does not.
The details that decide whether it looks deliberate
Three things separate concrete that reads as a considered surface from concrete that reads as a structural element someone forgot to cover.
Tie positions. Formwork ties leave holes. On a wall with a set-out drawing they become a grid; on a wall without one they become a rash. Setting out ties is a five-minute drawing exercise that is skipped on most projects and visible on all of them.
Pour joints. A day joint is unavoidable on any wall over about four metres. Detailed as a rebate it becomes a shadow line. Left as a butt joint it becomes a stain, because the two pours will not match in colour and the junction collects water.
The arris. A sharp external corner in concrete will chip. Always. A 20mm chamfer or a small radius survives forty years of trolleys and shoulders; a sharp arris survives about eighteen months, after which the building has a permanently damaged edge at every corner up to shoulder height.
Colour is a supply chain problem
Cement colour varies by batch, by plant, and by season. Aggregate colour varies by quarry face. Neither is controllable from a drawing.
What is controllable is the supplier. Concrete intended to be seen should come from one plant, ideally one silo, with the mix locked and the delivery slots booked. This is a logistical commitment made months before the first pour, and it is the single most reliable predictor of whether the finished walls will match. When a project’s fair-faced concrete comes out patchy, the cause is almost never the workmanship on site; it is that the mix changed halfway through because the original plant could not supply.
Rule of thumb Build a sample panel, at the size of the largest single pour, in the position on site with the worst exposure, and leave it up for the whole job. It is the only specification anyone can actually argue with.
Why it still wins on the long view
Concrete’s carbon problem is real and this magazine is not going to pretend otherwise: cement clinker is the issue, the substitutions are partial, and the honest first question on any project is whether the concrete is needed at all.
But once it is there, it is there. It requires no coating, no cladding, no periodic replacement, and no proprietary component that will be discontinued. It tolerates being drilled, cut, and loaded by people who have never seen the original drawings. Buildings that survive a change of use tend to be the ones whose structure was indifferent to what happened around it, and in-situ concrete is the most indifferent material we build with.
It just insists, permanently and in public, on showing you exactly how it was made.
