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Sitework & Earthworkaka: filter fabricaka: geofabricaka: separation fabric

Geotextile

In Plain English

A synthetic fabric used underground to filter, separate soil layers, or reinforce weak ground.

Definition

A permeable synthetic fabric used in construction applications including filtration, separation, reinforcement, and drainage. Geotextiles prevent soil migration into drainage aggregate (filter function), separate different soil layers (separation function), and can reinforce weak subgrades under fills or pavements. Types include woven and nonwoven geotextiles with different properties for each application.

Why It Matters in Bidding

Geotextile is an easy item to miss or misprice in earthwork takeoffs because it is specified by function and weight, and substituting the wrong type can fail inspection or compromise drainage. On poor subgrades it can substantially cut undercut and stone quantities, so understanding when it is required helps an estimator price the most cost-effective and competitive earthwork approach.

Example

Pricing a parking lot over soft soils, the estimator quantifies 4,000 square yards of nonwoven geotextile beneath the stone base to separate the subgrade and reduce the undercut the geotech report called for.

Related Terms

French DrainGravelSubgradeRiprap

Frequently Asked Questions

Woven geotextiles offer higher tensile strength and suit reinforcement and separation under loads, while nonwoven fabrics provide better permeability for filtration and drainage. Specifications call out the type, weight, and required properties, so estimators must price the specified fabric; substituting a cheaper grade risks rejection and rework at inspection.
Geotextile is typically taken off and priced by the square yard or square foot of coverage, with an added allowance for overlap at seams, often a foot or more per the manufacturer and spec. Estimators should add waste for trimming around utilities and edges so installed quantity matches ordered material.
When the subgrade is weak, a separation or reinforcement geotextile can reduce the depth of undercut and imported stone needed to stabilize it, lowering excavation, haul-off, and aggregate costs. Comparing the fabric cost against the avoided earthwork quantities often makes geotextile the more competitive approach on soft soils.

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