What are technical flats?

Technical flats are clean, to-scale drawings of a garment laid flat, front and back, with every seam, dart, topstitch and opening drawn where it sits. They are also called fashion flats or flat sketches. They show the garment as it is built, not as it looks on a body, and they are the drawing a factory measures, cuts and sews against. In a tech pack, every other sheet points back to them.

A flat is not meant to be beautiful. It is meant to be read the same way by a pattern maker in one country and a machinist in another. That is a different job from the drawing most designers start with.

How a flat differs from a sketch or an illustration

A fashion illustration sells a mood. The figure is elongated, the fabric moves, and the drawing leaves out whatever would spoil the line. A design sketch is closer, but it is still a note to yourself: quick, loose, and full of decisions that have not been made yet. Both are useful. Neither can be measured.

A flat removes the body and the movement. The garment lies flat, as it would on a cutting table, drawn to its real proportions. If the waist seam sits a third of the way down the body, it sits there on the drawing. The left and right sides match, because they match in the garment. If the design is asymmetric on purpose, the flat shows exactly where.

A quick test: could someone count the buttons, follow every seam to where it ends, and tell which edges are topstitched? If not, it is still a sketch.

What a factory reads from a flat

A workroom does not look at a flat as a picture. It reads it, line by line, for information that will become pattern pieces and sewing operations.

• Proportion. Where the waist seam falls, how long the sleeve is against the body, how wide the collar is against the shoulder. The pattern maker drafts from the spec, then checks the shape against the flat.
• Seam lines. Every line on a flat is a seam, an edge, a dart or a fold. A pattern maker counts the pieces from them. A missing line becomes a missing piece, or a panel cut in one where you wanted two.
• Stitching. Topstitching is drawn as a fine broken line beside the seam, at the distance it will be sewn. Single or double needle should be clear from the drawing alone.
• Closures and openings. Button count and spacing, zip length and where it stops, which side the placket overlaps, and where each pocket opens.
• Details that change the cut. Pleats, gathers, darts, a yoke, a vent, a slit. Each one means extra fabric or an extra piece.

Drawn well, a flat answers most of these before anyone writes a note. Drawn loosely, the factory reads a guess, and the first sample shows which guess they made.

Front, back, and sometimes inside

Every garment needs a front flat and a back flat, drawn at the same scale and placed side by side, so a seam that wraps around the side lines up on both. The back is where the quiet details sit: a yoke, a centre back seam, a vent, a back neck facing, the brand label. Leaving the back out does not make those details go away. It leaves them to whoever cuts the first sample.

Some styles need more. A lined jacket may need an inside view. A collar that is hard to read when closed may need a flat with the collar open, or a side view. Draw what the factory would otherwise have to imagine.

Callouts, notes and close-ups

A full flat of a shirt is often too small to show a collar stand or the spacing of 15 mm buttons clearly. That is what a callout is for: a circle around one area, drawn again at a larger size beside the flat. It takes a few minutes and saves a misread placket. How to make a tech pack shows one on a centre front placket.

Notes on the flat should be short and point to one place each, with a line. “Double needle topstitch, 6 mm from edge” beside the armhole is a method. “Nice clean finish” is a hope. Measurements belong on the spec sheet, where each point of measure is defined. Numbers scattered across the drawing tend to drift from the spec, and sooner or later two of them disagree.

Where flats come from

Flats are drawn by hand, in a vector drawing programme, or traced from an approved 3D sample. The tool matters less than the discipline: one set of flats, drawn once, used on every sheet. If the collar on the lead sheet is wider than the collar on the construction sheet, the factory has to pick one, and it may not pick yours.

A 3D sample is a useful place to settle proportion before the flats are final. When I draw flats from an approved 3D sample, the hem length, collar width and pocket placement have already been decided on the garment itself. The drawing records a decision instead of making one.

Common mistakes in technical flats

• Drawn on a figure or in a pose, so the proportion follows the body instead of the garment.
• Shading and fabric texture that hide the seam lines.
• A front with no back.
• Front and back at different scales, so the side seams do not meet.
• Topstitching drawn on some edges and not others, when it is sewn on all of them.
• Buttons drawn as a rough row, so the count and spacing have to be guessed.
• Flats that change between sheets after a revision, because only one page was updated.

Flats inside a tech pack

In a tech pack, the flats sit on the lead sheet, carry the construction notes, show the points of measure on the spec sheet and the position of every label. What is a tech pack? lists the sheets they appear on. They are the reference the rest of the pack is checked against, and the drawing a factory goes back to when two pages seem to disagree.

That is why they are worth drawing carefully before anything else is written. A seam that is right on the flat is easy to describe in the construction notes, measure on the spec and grade across the sizes. A seam that is wrong on the flat is wrong on every page after it.