Butt Purlin Run
A run of steel zed purlins, one length per bay butted at every rafter, bolted to a cleat at each support and braced by anti-sag rods between the lines. Bays along the run and the bay span, Rafter length and the largest line spacing, Purlin depth and thickness, Cleat width and anti-sag rod rows, Frame section depth and column height
Details
Category: Roof Framing › Steel Purlins › Purlin and Girt Runs
By Huu Khanh Nguyen · Updated November 5, 2026
Parameters
| Name | Default | Unit |
|---|---|---|
| Bays | 5 | |
| Bay Span | 6000 | mm |
| Rafter Length | 3600 | mm |
| Largest Line Spacing | 1200 | mm |
| Purlin Depth | 203 | mm |
| Purlin Thickness | 1.9 | mm |
| Cleat Width | 75 | mm |
| Bridging Rows | 2 | |
| Finish | steelZincAluminium | |
| Frame Section Depth | Math.round(2.5 * depth / 50) * 50 | mm |
| Column Height | 6000 | mm |
| Run Length | bayCount * span + 2 * Math.max(0.525 * frameDepth, cleatWidth / 2) | mm |
| Height | cleatGap + depth + frameDepth + columnHeight + Math.round(frameDepth / 20) | mm |
| Line Intervals | Math.ceil(rafterLength / maximumSpacing) | |
| Line Spacing | rafterLength / lineIntervals | mm |
| Cleat Gap | depth <= 250 ? 10 : 20 | mm |