Scaffold Debris Netting: Vertical Drops, Rolls, Ties, Area & Mass for a Facade

The formula

This is the expression the tool evaluates. Every term is named underneath, with the unit it must be supplied in.

How the result is derived

Step by step, from the values you type to the figure on screen.

1. The 8 inputs are read from the form on every keystroke: Scaffold Run to Net, Scaffold Height to Net, Extension above the Top Lift, Overlap between Drops, Tie Spacing up Each Seam, Roll Width, Roll Length and Netting Weight.
2. Each value is checked against the accepted range in the input table below. A value outside its range stops the calculation rather than producing a misleading figure — the results blank out and a message appears.
3. The validated values are substituted into the expression above, which resolves Rolls to Order together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Drops along the Run, Length of Each Drop, Whole Drops from One Roll, Ties along the Seams and Edges, Netting Hung, Scaffold Face Covered, Netting Mass Hung and Roll Left at the End of Each Roll — come from the same pass, so they always describe the same case as the headline figure.
5. Results are rounded for display only. The full-precision value is used throughout the chain, so reading a rounded intermediate figure back into the tool by hand can shift the last digit.

What each input means

Where to read each value on the floor, the unit it must be in, and the range the tool accepts.

What the tool returns

The headline figure and every supporting value it is built from.

Worked example

Substituting

Each 50 m roll gives two 19 m drops and 12 m of offcut: almost a quarter of every roll.

How to use it

1. Work through the input groups in order — Scaffold and Netting Roll. The defaults are a realistic case, so you can change one value at a time and watch what moves.
2. There is no calculate button. Every figure recalculates as you type or drag, which is what makes this usable for a what-if sweep rather than a single answer.
3. Read Rolls to Order in the dark results panel — that is the headline figure, expressed in rolls.
4. Check the supporting rows underneath (Drops along the Run, Length of Each Drop, Whole Drops from One Roll, Ties along the Seams and Edges, Netting Hung, Scaffold Face Covered, Netting Mass Hung and Roll Left at the End of Each Roll) before acting on the headline — they are where an implausible input usually shows itself first.
5. Reset to defaults returns every field to the reference case, which is the quickest way to check whether a surprising result came from the tool or from an input you had changed earlier.

Where this is used

• Process planning — establishing Rolls to Order before a trial is booked, so machine time and material in Cordage, Ropes & Heavy Netting are committed against a calculated figure rather than an estimate.
• Costing and quotation — Rolls to Order is an input to the cost sheet, and quoting from a worked number rather than a remembered one is what keeps a margin intact.
• Troubleshooting — when the floor result drifts from plan, entering the measured values (starting with Scaffold Run to Net) shows how much of the gap in Rolls to Order each variable explains.
• Teaching and study — the accepted ranges bracket normal Cordage, Ropes & Heavy Netting practice, so moving one variable at a time shows the shape of the relationship rather than a single answer.

Reading the result

Typical bands and what each one is telling you.

Assumptions and limits

• Drops hang from the top of the scaffold to the base, each overlapping its neighbour by the lap you enter; the run, height, extension and tie spacing are the scaffold design's. Ties are counted up every seam and both outside edges at the tie spacing, with one at each end; ties along the top and bottom rails are extra. A roll gives only whole drops, and the end of each roll too short for another drop is offcut. Returns round corners are counted in the run. **Netting adds wind load to a scaffold: the scaffold must be designed for netting before any is hung, which this tool does not check.**
• Every input is bounded to the range normal practice occupies (Scaffold Run to Net 1 to 5000 m, Scaffold Height to Net 1 to 200 m and Extension above the Top Lift 0 to 5 m, and so on for the rest). Those bounds are guard rails against typing errors, not a claim that the formula fails one unit outside them.
• The calculation is deterministic: the same inputs always give the same result. It carries no allowance for machine condition, operator skill, ambient conditions or lot-to-lot material variation unless an input above explicitly represents one.
• Nothing is sent anywhere. The maths runs in your browser, so the numbers you type never leave the page.

Standards and further reading

• The scaffold design, which must allow for the wind load netting adds, and the scaffold contractor's method for fixing it.
• National construction safety rules for protecting the public and workers from falling materials.
• The netting data sheet: shade or open area, fire performance where required, UV life and weight per square metre.

Questions people ask