Slope From the drawing

Vertical Rise, Toe to Crest m

Gradient (Horizontal per 1 Vertical) H : 1V

2 for a 1V:2H slope. The same figure written 2:1 (H:V) on many drawings.

Width along the Slope m

Measured along the toe or the crest, across the direction the rolls run.

Crest Anchor & Run-Out Allowance cm

Blanket buried in the anchor trench at the crest and carried past the toe, added to every strip.

Blanket & Fixing From the product sheet and the specification

Roll Width m

Roll Length m

Side Lap between Strips cm

End Lap at a Join (Upper Roll over Lower) cm

Staple Pattern Density per m²

From the manufacturer's staple pattern for this slope, laps included.

Cutting & Damage Allowance %

A planning figure, not a measured loss.

Rolls to Order

— rolls

The larger of the count by length (with allowance) and the count by whole cuts

Layout

True Slope Length: — m
Slope Angle: — °
Strip Length incl. Anchor: — m
Strips across the Slope: — strips
End Joins per Strip: — joins
Linear Metres Laid: — m
Rolls by Length incl. Allowance: — rolls
Rolls if Each Strip Is Cut Whole: — rolls
Slope Area: — m²
Blanket Area Laid: — m²
Laps & Anchor above the Slope Area: — %
Staples or Pins: — staples

The tool lays every strip down the slope from the crest, so the true slope length, not the plan distance, sets the strip. Laps, the crest anchor and the staple pattern are the product sheet's and the specification's; the tool has no figure of its own and does not choose a blanket for the slope or the flow. When a strip is shorter than a roll, whole strips are cut from each roll and the offcut is counted as lost; when it is longer, strips are joined down the slope at the end lap. The order is the larger of the two roll counts. **This is a quantity take-off for a plane slope, not an erosion design.**

Erosion Control Blanket on a Slope: True Slope Length, Strips, Rolls & Staples — free, with the formula and a worked example, at Textile School.