Metal · Cutting · Roof truss
Steel roof truss cut list and cutting layout
What it does and how it is worked out
Type the cuts of your roof truss and the page lays them out on the fewest bars, with what is left of each one. Free, in the browser and on a phone. The list below is an example, four roof trusses in rectangular tube, with their purlins, 192 × 36 in: 40 pieces on 15 bars of 240 in, 99 % of the bar used. Clear it and put in your own cuts.
- bars
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- used
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- waste
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The example of this page, worked out
The list the page opens with is an example, not anybody's order: four roof trusses in rectangular tube, with their purlins, 192 × 36 in. Every length comes from the outside sizes of the job, and the figures are the optimiser's own, worked out by the same code as the tool above, on bars of 240 in with a 0.125 in cut and 0.5 in trimmed off each end.
| What the optimiser answers | Figure |
|---|---|
| Bars to buy | 15 |
| Pieces | 40 |
| Bar used | 99.0 % |
| Waste: blade, trim and short ends | 1.0 % |
| Offcuts worth keeping, 12 in or more | 13 · 26.6 ft |
King postVerticalBottom chordDiagonalPurlinTop chord
The cutting list of the example
| Piece | Qty | Length, in |
|---|---|---|
| Bottom chord | 4 | 192 |
| Top chord | 8 | 102.5 |
| King post | 4 | 36 |
| Vertical | 8 | 18 |
| Diagonal | 8 | 51.25 |
| Purlin | 8 | 120 |
The same list on the main optimiser, with other bar lengths and your own offcuts: open it there.
What to watch: roof truss
- Lengths on centre lines. The top chord is the hypotenuse of half the span and the rise, and the diagonals the same between their two ends. Where two members meet at an angle the cut is not square: add what your joint needs, or cut a little long and trim on the jig.
- Equal parts, cut in a batch. Four trusses are four times the same list: the optimiser pairs a long chord with the short members that fill what it leaves of the bar.
- A chord longer than the bar is spliced. A bottom chord longer than the bar you buy has to be made of two parts: put them in as two rows.
- Your bar, your blade, your trim. The example is on bars of 240 in with a 0.125 in cut and 0.5 in trimmed off each end. Set the bar your supplier sells and the width of your blade: the plan is worked out again as you type, and so is what is worth keeping (12 in or more here).
Templates: roof truss
Example sizes, not a standard: load one into the list above, then change each length to yours. Loading one replaces the list; nothing is sent and no email is asked for.
Bars and bar used on bars of 240 in, as the optimiser works them out. What the bars weigh: metal weight calculator.
Questions people ask
- How many bars does a roof truss take?
- The example on this page, four roof trusses in rectangular tube, with their purlins, 192 × 36 in, is 40 pieces and takes 15 bars of 240 in with a 0.125 in cut and 0.5 in trimmed off each end: 99.0 % of the bar is used and 13 offcuts are worth keeping. Put in your own cuts and the page works out yours.
- How long is the top chord of a truss?
- The square root of half the span squared plus the rise squared, on centre lines: the example, with a 192 in span and a 36 in rise, has top chords of 102.5 in.