Industry-standard dimensions (ANSI/ASABE S618)

Choose whether your numbers mean the industry standard or your old drawing-set convention, and switching relabels the numbers without moving the building.

What it is

Every saved design carries a dimensionConvention. S618 (the default) measures eave, rake and ridge to the TOP OF PURLINS and width/length outside-of-girt to outside-of-girt. 'structural' measures to truss bearing and post line. The engine always builds in structural lines; structuralSpec is the single conversion point.

Also called: S618 · eave height to top of purlins · outside of girt dimensions · structural lines

See it
Industry-standard dimensions (ANSI/ASABE S618)
Prepared for
Ivy Brubaker
1140 Ridge Line Rd · Fair Play
Shell package$35,073
Concrete & site$10,183
Doors & windows$6,788
Trim & finish$4,526
Total
$56,570
Signature
Panel screenshot of the convention Select with its blurb, plus a callout showing the same building labelled 14ft (structural) and 14ft-8.5in (S618). Sample data — no customer information appears here.
How it works
  1. 1s618Offsets(pitch) computes the vertical offset (top chord + purlin depth, less the girt-outside pitch term) and the plan offset (girt thickness per side).
  2. 2structuralSpec() converts an S618 spec once, at the top of deriveBuilding, so there is exactly one place a convention can be misread.
  3. 3convertSpec() restates a saved design in the other convention: the numbers change, the building does not.
  4. 4migrateSpec() converts specs authored before the setting existed rather than reinterpreting them, so the shipped presets come out byte-for-byte identical.
  5. 5Drag handles read world values and convert with fromStructuralValue, so the 14ft and 16ft snap rungs mean the standard's eave line.
Why we built it

The industry standard measures a building off the top of the purlins and the outside of the girts; the engine had always worked in structural lines. A spec that said a 14ft eave was, in the terms a supplier and an inspector use, a 14ft 8.5in building — and every elevation printed off it was wrong by that much. A design now states which convention it is in, defaulting to the industry one, because plenty of shops and every drawing set already in a customer's hands speak structural lines. A stored number is never silently reinterpreted: the convention travels with the design.

The problem
  • A number stored under one convention read under another shifts every elevation by a purlin depth.
  • Shops with existing drawing sets cannot adopt a tool that forces a different convention.
Sound familiar?
What you get
Eave, rake and ridge match what suppliers, truss plants and the NFBA design manual mean.
Legacy designs migrate to the standard without the building changing shape.
Snap ladders land on the standard's numbers, not on internal structural values.

See it on your own jobs

Twenty minutes, your numbers, no slide deck. We’ll build one of your real buildings in front of you and send you the estimate link at the end — yours to keep either way.

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