Finishes
Marking Out Lines and Sports Courts
A court is a geometry problem that ends in a spray gun: how to set out, prove and record the lines before any paint is mixed.
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Start From What Cannot Move
Every line you will ever spray is a consequence of two decisions taken before a tin is opened: where the origin sits and which direction is true. Take a wall as your reference and you inherit whatever the blockwork gang left behind — a 40 mm bow across 20 m is unremarkable in masonry and stays invisible until a baseline runs visibly out of parallel with it. Establish your own centreline instead, struck between two permanent marks you can recover: drilled and plugged points, saw-cut kerfs, brass inserts set flush in the slab. Recoverability matters more than precision at this stage. Somebody will scrub your chalk off between coats, and a datum you cannot re-find was never a datum.
Origin at the centre of the court, wherever the geometry allows. Working outward in both directions halves any accumulated tape error instead of piling it all at one end, and it keeps the two halves symmetrical — which is what a player, a referee and an inspector actually notice. Symmetry survives scrutiny; the absolute dimension rarely gets measured on handover day, but an off-centre net post gets spotted from the balcony in seconds.
Walk the run-offs before committing. A hall that measures fine on the drawing can still leave you 600 mm short behind a baseline once retractable seating, a door swing and wall padding are accounted for. Shifting the whole court 300 mm along its long axis at setting-out stage takes ten minutes; discovering the clash after the arcs are cut in means grinding back a finished floor and re-coating a bay of it.
Prove the Rectangle Before You Believe It
Two tapes and a competent helper will square a court more reliably than most laser tools in a dusty hall, provided the triangle is scaled up. A 3-4-5 struck at three metres is worthless over 28 m — the angular error in a 5 mm mis-mark magnifies all the way down the sideline. Use 12-16-20 m, or 15-20-25 m, and set the right angle at the court centre rather than at a corner, so any residual error is shared between the two halves.
Diagonals settle the argument. Once the four corners are pegged, measure corner to corner both ways: equal diagonals prove the figure is a rectangle, and only then do the side dimensions mean anything. A full-size basketball court at 28 by 15 m gives a diagonal of roughly 31.76 m; a doubles tennis court at 23.77 by 10.97 m gives roughly 26.18 m, which is why the ITF publishes a diagonal as a check dimension alongside the sides. Hold the two diagonals within a few millimetres of each other — tighter than the dimensional tolerance the rulebook permits, because the difference between them, not the absolute length, is what reads as a skewed court.
Tapes lie under the wrong conditions. Steel tapes are graduated for a stated temperature and tension, usually printed on the blade; drag a 30 m steel tape slack across warm asphalt in July and you can gain or lose ten to fifteen millimetres with no visible cause. Fibreglass tapes stretch worse, and stretch permanently once abused. Keep one tape on the job for every critical dimension, keep the pull consistent, and never fold a measurement taken with a second tape into a chain checked with the first.
Which Edge Carries the Dimension
Line width is a dimension, not a finish. Codes differ on whether the stated court size runs to the inside, the outside or the centre of the line, and getting that convention backwards doubles the error — a 50 mm line placed on the wrong side of the mark puts each sideline 50 mm out and the overall width 100 mm out.
Under FIBA rules the playing court is measured to the inner edge of the boundary lines, so the lines sit outside the nominal playing area and belong to the surround. Tennis works the opposite way: the ITF takes court measurements to the outside of the lines. Badminton, volleyball and netball each state their own convention in their own rulebook. Read the current edition of the governing body's document for the sport being marked, because these documents are revised and working from last season's crib sheet is a common route to a court that fails inspection.
Widths themselves are specified rather than chosen. Basketball uses 50 mm lines; tennis permits a range for most lines with the baseline allowed wider. Consistency across the job counts as much as the number — a court where the sidelines run 50 mm and the service lines drifted to 60 mm because the gun was held closer looks wrong in photographs even where no rule has been broken. Cut widths with tape or a fixed-width shoe, never by eye.
Arcs, Pivots and Points You Cannot Stand On
Arcs fail because the pivot was placed by assumption. The three-point line under FIBA rules is struck from the point on the floor vertically beneath the centre of the ring — not the centre of the backboard, not the midpoint of the baseline, and not the free-throw circle centre. That projected point sits inside the court by a distance governed by the backboard overhang, and it has to be established from the goal as installed, not from the drawing, because goal installation carries its own tolerance and rarely lands dead on paper.
Strike arcs with a trammel, not a string. Nylon line stretches under the pull needed to keep it straight, and the stretch varies with how hard the person holding it happens to be concentrating; over a radius of nearly seven metres that is easily ten millimetres of wander around the curve. A timber or aluminium bar with a pivot pin at one end and a scribe at the other gives a repeatable radius every time. Check the struck arc with chord measurements at three or four points before taping — a chord reading short tells you the pivot shifted.
Tangents catch people out. Where a corner straight meets a curve the two must meet cleanly, or the eye reads a kink from thirty metres away. Mark the tangent points from the geometry rather than fairing the curve in by hand, and confirm the straight sections sit parallel to the sideline at both ends, not merely at the end you happen to be standing on.
The Surface Decides How Sharp the Line Can Be
Geometry that is perfect in chalk still comes out ragged on the wrong substrate. New asphalt carries oils that reject waterborne paint and encourage bleed under tape; the cure period before marking is set by the surfacing specification and local practice, and shortening it because a tournament date moved is a decision that shows up in every line on the court. Acrylic resurfacers are laid to fill texture precisely so an edge can be cut sharp — mark straight onto an open-textured wearing course and the paint wicks along the aggregate however well the tape is bedded.
Indoors the constraints are compatibility and moisture. Line paint has to bond to the seal or finish specified for that floor system, and the sequence — seal, mark, seal again — belongs to the floor manufacturer rather than to the marking contractor. Timber floors want the hall's temperature and humidity settled before anything is applied. EN 14904, covering indoor surfaces for multi-sports use, and ASTM F2772 for indoor sports floor systems both frame the performance the finished floor must deliver, and a marking job that softens or lifts the finish puts that performance in question.
Falls and flatness form part of the setting-out. Outdoor courts are laid to a designed cross-fall so water sheds, with direction and grade fixed by the design and by whatever facility guidance the governing body publishes for that sport; run lines across a fall nobody surveyed and standing water will sit on a baseline for the life of the surface. Flatness measured to ASTM E1155 on an interior slab gives a number to argue with before work starts, which is worth considerably more than a complaint afterwards.
Straight Runs and the Linear Take-Off
Once the rectangle is proved, the quantity take-off falls out of it almost for free. Total the linear metres by line width — perimeter, service lines, centre lines, hatched areas, plus any adjacent striping such as access aisles, run-up lanes or athletics straights that shares the same mobilisation. Volume scales with width as well as with length, so a job that switches from 50 mm to 100 mm lines doubles the paint on every metre of that line type.
Texture is the variable that wrecks estimates. A smooth sealed indoor floor may take a fraction of what an open outdoor acrylic takes over the same metre, and a second coat over a porous surface seldom draws as much as the first. Build the figure per coat rather than as a single lump, and allow for what disappears into overspray, gun purging and the tape itself.
Order in one batch per colour wherever the programme allows. Two batches of nominally identical white can differ enough to read as a repair patch under hall lighting, and a court re-marked in halves across two visits shows the join from the seats. Where a second batch cannot be avoided, break at a natural boundary instead of part-way along a line.
Perimeter and straight-run lengths are the first hard numbers the setting-out produces, so this is the point at which linear metres turn into litres per coat.
Striping paint needed
3 gallons
Coverage assumes a standard 4 in wide line at typical thickness — wider lines, stenciled symbols, or a second coat use more paint per linear ft.
- Total line length
- 655 linear ft
With the figures above, the striping paint needed comes to 3 gallons. The method behind this is well established, though site conditions and material batches will move it somewhat. This is presented for United States. Building in another market? Change the selector above and the units and terminology follow.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
Overlays: Deciding Which Geometry Wins
Multi-sport halls force a hierarchy. One sport gets the dominant colour and the uninterrupted lines; everything else is subordinate, and that decision belongs to the client and the facility's competition programme rather than to whoever is holding the gun. Settle it in writing before setting out, because an overlay that has to be reversed means stripping and re-coating the whole floor, not just the offending lines.
Shared geometry cuts confusion where the codes allow it. Common centre points, coincident sidelines and shared centre circles reduce visual noise and linear metres at the same time. Where two lines from different sports would otherwise run close and near-parallel, they read as one blurred band from the far end of the hall; governing body facility guidance sets what separation or interruption is acceptable, and the answer differs by sport and by level of competition.
Colour carries a legibility requirement, not a preference. Contrast against the field colour has to hold under the lighting the venue actually uses, which is rarely what the sample card assumed. Lay a test patch on the finished surface and view it from the referee's position with the play lighting on — a yellow that sang in the back of the van can vanish against a light maple floor.
Committing the Geometry to Paint
Transfer the setting-out to the surface twice. Snap a chalk line, mask to it, then check the masked edge back against the datum before spraying — tape wanders when it is pulled around a long run, and a 5 mm drift at the midpoint of a sideline is far easier to correct with a knife than with a grinder. On curves, use short lengths of flexible fine-line tape and repeat the chord checks after masking rather than trusting the strike.
Bleed control decides whether the finished line looks cut or sprayed. Sealing the tape edge with a thin pass of the background colour before laying on the line colour fills the micro-gaps and produces a clean edge even on textured acrylic. Lift tape while the film is still soft enough to release cleanly instead of after full cure, and work inside the temperature and dew point window the coating data sheet defines — applied below the stated minimum surface temperature, a film can look perfect and still fail its first frost.
Two thin coats beat one heavy pass on every count that matters: edge definition, cure, and the wet film thickness the product was formulated around. Heavy single passes sag on a cross-fall, creep under tape and cure soft in the middle where nobody sees it until the surface is in use.
With the geometry proved and the masking set, the court's own arcs, keys and boundary lines convert here into a per-colour, per-coat quantity.
Line marking paint needed
0.3296 gal
- Total line area
- 107.45 ft²
For the dimensions entered, expect a line marking paint needed of 0.33 gal. Set for United States. The market selector changes the units and the trade terminology; any standard behind the formula is cited under sources.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
Proving It: the As-Built Check
Re-measure after painting, not only before. Diagonals, both baselines, the centre line offset and at least three chord checks on each arc — recorded, dated and signed on a marked-up copy of the layout drawing. That record is the only defence available when a visiting official queries a dimension six months later, and it takes twenty minutes on a court that is already finished.
Photograph the datum points before they vanish under the final coat, with a tape in frame and the offsets noted. Whoever resurfaces the court next will benefit, and when that contractor turns out to be you, re-establishing the setting-out becomes an hour's work instead of a full survey from the building shell.
Fixed equipment belongs in the same check. Net post positions, goal sockets, sleeve centres and floor inserts all have to agree with the painted geometry, and where they disagree the paint is almost always cheaper to move than the sockets. Confirm that relationship before the last coat goes down, while a correction is still a masking exercise rather than a resurfacing one.
Setting-out take-off and checks
What to have on the barrow and in the notebook before the first line is masked, arranged in the order the geometry needs it.
- Two recoverable datum points — Drilled and plugged, or brass inserts flush with the surface; offsets written down, not remembered.
- One steel tape for all critical dimensions — Same tape, same tension, both diagonals; note the surface temperature if working outdoors in summer.
- Trammel bar cut to each arc radius — Pivot pin one end, scribe the other; string stretches by an amount nobody can control.
- Linear metres tallied by width and colour — Separate the 50 mm lines from anything wider before converting to volume, and split the total per coat.
- Fine-line masking tape plus background colour for edge sealing — A thin sealing pass of the field colour under the tape edge is what makes a cut line on textured acrylic.
- Signed as-built check sheet — Diagonals, baselines, centre offset and three chord readings per arc, taken after the final coat.
Opens the calculators above on one screen with the dimensions from this article already filled in. Quantities only — this site publishes no price list, because local prices vary too much to publish honestly.
Drawn from
- FIBA Official Basketball Rules and Basketball Equipment (current edition)
- ITF Rules of Tennis (current edition)
- BWF Laws of Badminton (current edition)
- FIVB Official Volleyball Rules (current edition)
- World Athletics Track and Field Facilities Manual
- EN 14904 Surfaces for sports areas - Indoor surfaces for multi-sports use - Specification
- EN 14877 Synthetic surfaces for outdoor sports areas - Specification
- ASTM F2772 Standard Specification for Athletic Performance Properties of Indoor Sports Floor Systems
- ASTM E1155 Standard Test Method for Determining FF Floor Flatness and FL Floor Levelness Numbers
- EN 13036-4 Road and airfield surface characteristics - Test methods - Part 4: Method for measurement of slip/skid resistance of a surface: The pendulum test
- Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD)
Guidance, not a specification. Local codes, the engineer of record and the product manufacturer’s instructions govern where they differ from anything written here.