DSTV / NC1 files: what they are and why estimators should use them

Takeoff & imports · ~6 min read

Every detailed steel job already produces a set of files that describe each piece exactly: profile, length, every hole, every cope. Most estimating desks never touch them. That's free precision left on the table.

What a DSTV file is

DSTV is a plain-text CNC file standard from the German steel construction association, and in practice you'll meet it as files ending in .nc1 (sometimes just .nc), one file per piece. Detailing packages like Tekla Structures, SDS/2, and Advance Steel export them as a matter of routine, because DSTV is what beam lines, drills, and coping machines actually read on the shop floor.

Inside each file is a header and a set of feature blocks. The header carries the piece mark, profile (say W18X50), grade, length, and quantity. The feature blocks describe the work: hole positions and diameters by face, copes and notches, miter cuts, and markings. It's the piece's shop drawing, written for a machine.

Why that matters at the estimating desk

An estimate is mostly a list of pieces and the operations each one needs. A DSTV set is that list, produced by someone else, with no transcription in between:

• Exact material. Profile, grade, and length per piece. No section misread off a drawing, no length rounded from a plan dimension.
• Real operation counts. The holes in the file are the holes the drill will run. If you price shop labor by operation (cut, drill, cope), DSTV gives you the counts instead of an allowance.
• A piece count you can trust. Erection pricing runs on picks (see picks, not tons), and a DSTV set counts them for you.
• Fast change pricing. When a revision lands as a new file set, importing both and comparing totals beats re-measuring a drawing every time.

When you'll actually have them

You won't get .nc1 files at hard bid on design drawings; they exist once someone has detailed the job. Where they show up for an estimator:

• Change orders and revisions on a job your shop already holds, where detailing is done and the files exist.
• Fab-only quotes, where a GC or another fabricator sends a detailed package and wants a processing price.
• Design-assist and negotiated work, where detailing runs ahead of the final number.
• Checking your own bid after award: import the detailed set and compare it against what you priced. The difference is your takeoff error, measured, before the shop finds it.

A few practical notes

• One file per piece means hundreds of files. Import the folder, not the file. Good software rolls identical pieces up by mark and quantity.
• Files are only as good as the model. A wrong grade in the model is a wrong grade in the file. Spot-check a handful of pieces against the drawings, the same way you'd check an advance bill.
• Watch the units. DSTV dimensions are metric internally; a proper importer converts. If a 40-foot beam imports at 12, something read millimeters as feet.
• They complement, not replace, the takeoff. Misc metals, deck, and loose hardware usually aren't in the DSTV set. It covers the main-member story; the estimate still owns the rest.

Read next: Steel takeoff from Bluebeam →