Square by the Diagonals

Square when the diagonals are equal.

The CPCCCA3002 benchmark: the two diagonals must agree within 3 mm, measured over a diagonal of at least 10 m. If they differ, the set-out is out of square — adjust a string line and re-check.

Diagonal A–C

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Diagonal B–D

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Difference

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tolerance ≤ 3 mm

SQUARE ✓ Diagonals under 10 m — the 3 mm benchmark is assessed over diagonals of at least 10 m. Try a bigger footprint.

1 · Explore the relationship

Set the footprint with the sliders, then drag corner C (or push the line out with the buttons) and watch the two diagonals split apart. Nudge the back string line along its profiles to bring them back together — just like tapping a nail across on site.

Length A–B 12.0 m

Width A–D 8.0 m

Nudge back line: mm

✓Knock it out of square — drag corner C at least 15 mm off line.

✓Nudge it back until the diagonals agree within 3 mm.

1 · Explore the relationship

2 · Predict before you measure

3 · Square-up challenge 1 of 3

4 · Signed off

The takeaway