Area Rectangle & allowances

Length along the Roll Run m

The direction the rolls are unrolled, usually along the road, track or trench.

Width across the Rolls m

Edge Allowance on Each Side m

Fabric turned up a trench wall, into an anchor trench or past the formation edge, added on every side. Enter 0 if the fabric stops at the edge.

Roll & Laps From the data sheet and the specification

Roll Width m

Roll Length m

Side Overlap between Strips mm

The lap the specification calls for between adjacent strips. Sewn seams need less; soft ground needs more.

End Overlap at a Join mm

Where one roll ends and the next starts along the run.

Cutting & Damage Allowance %

Cut-outs, torn roll ends and rolls spoiled in storage. A planning figure, not a measurement.

Rolls to Order

— rolls

Linear metres plus the allowance, divided by the roll length, rounded up

Layout

Strips across the Width: — strips
End Joins per Strip: — joins
Linear Metres Laid: — m
Linear Metres incl. Allowance: — m
Rolls if Every Strip Starts a Fresh Roll: — rolls
Area to Cover incl. Edge Allowance: — m²
Fabric Area Laid: — m²
Laps & Trim above the Net Area: — %
Trim on the Far Edge: — m
Fabric Area Delivered: — m²

Overlaps are the project's: specifications set the side lap by subgrade strength (AASHTO M 288 tabulates it against CBR), and sewn seams replace most of it. The strip count assumes rolls run parallel in one direction; try the area the other way round and compare the far-edge trim. Two roll counts are given because site practice varies: the roll count by length assumes a roll that ends mid-strip is carried on to the next strip, the fresh-roll count assumes every strip starts a new roll. The wastage allowance is whatever you enter; it is not a measured loss. **This is a quantity take-off for a rectangle, not a design: it does not choose the geotextile, the lap or the orientation for you.**

Geotextile Roll Count, Overlap & Wastage for an Area — free, with the formula and a worked example, at Textile School.