Buy nonwoven geotextile against a written application specification, not GSM alone. Confirm the material and construction, soil-compatible filtration properties, required mechanical performance, roll dimensions, reporting basis and delivery documentation. Compare total usable coverage and delivered cost only after the technical requirements are aligned.
This guide is for contractors, distributors and project buyers requesting quotations. It covers drainage, roadway separation, erosion-control filters and liner-protection layers. A product suitable for one function is not automatically suitable for the others.
Project Application and Matching
Subsurface Drainage
A nonwoven filter between soil and drainage aggregate must retain the soil adequately while allowing water to pass. Collect the soil grading and relevant plasticity information, expected flow conditions and drain details before selecting it. A soil label such as “sand” or “clay” is not enough to assign a universal sieve number.
ASTM D4751 measures apparent opening size (AOS), an indicator relevant to soil compatibility. Ask for the result in millimeters, the method used and its specified acceptance limit. AOS alone does not guarantee that a drain will stay unclogged. For the design checks, see soil retention and geotextile flow capacity.
Keep the filter, aggregate, pipe and outlet requirements coordinated. A fabric cannot remedy an undersized outlet, unsuitable backfill or incorrect drain level. Trench depth must follow the site design; 18–24 inches cannot be assumed to be below the frost line across the United States.
Roadway Separation
Provide the subgrade condition, aggregate size, construction equipment and cover requirements. Select for survival during installation as well as separation in service. Where AASHTO M288 is invoked, use the contract edition and application-specific requirements. Its classes are not fabric-weight bands, and nonwoven geotextile does not automatically replace three or four inches of aggregate.
Erosion Control, Retaining Walls and Liner Protection
For riprap or retaining-wall filtration, confirm both soil compatibility and resistance to installation damage. FHWA’s rockery guidance illustrates why the filter must be checked against retained soil and protected during delivery and storage; its specific requirements should not be applied to every wall or shoreline.
A nonwoven protection cushion above or below a geomembrane has a different selection task. Supply the liner details, aggregate grading, loading and service conditions for assessment. A nominal fabric weight or CBR puncture result alone does not prove that the complete liner system will resist long-term indentation or damage.
Fabric Weight and Thickness: Compare Like with Like
Convert GSM and Ounces per Square Yard Correctly
GSM means grams per square meter. 1 oz/yd² ≈ 33.906 g/m². Use the following conversions to compare quotations; these are arithmetic equivalents, not product grades or application recommendations.
| Nominal mass | Approximate GSM | What remains to be checked |
|---|---|---|
| 3–4 oz/yd² | 102–136 g/m² | Actual filtration and strength requirements |
| 6–8 oz/yd² | 203–271 g/m² | Product-specific test data and installation survivability |
| 10–16 oz/yd² | 339–542 g/m² | Required protection or other application performance |
Two fabrics with equal mass can differ in polymer, fiber structure and consolidation. Request the declared polymer—such as PP or PET—and any project-required composition information. Recycled content or virgin content by itself does not prove compliance, durability or noncompliance; assess the finished product and the stated specification.
Thickness Is a Separate Measurement
1 mil = 0.0254 mm, so 60 mil is 1.524 mm and 150 mil is 3.81 mm. Unlike a solid sheet, nonwoven thickness changes with applied pressure. Ask for the test method, measurement pressure and nominal value; do not infer thickness from GSM or treat uncompressed thickness as a guaranteed in-service value.
Request durability evidence for the relevant environment rather than a general “50-year life” assurance. Chemical exposure, temperature, loading and installation conditions matter. An ISO management-system certificate is useful supplier information but does not replace test evidence for the product being ordered.
Permeability and Strength: Keep the Units Separate
| Property | Unit to identify | Procurement check |
|---|---|---|
| Permittivity | s⁻¹ | Test method and specified minimum |
| Flow per unit area | For example, US gpm/ft² | Hydraulic head and test conditions |
| Hydraulic conductivity | For example, m/s | Measurement basis; not interchangeable with permittivity |
| Grab breaking load | N or lbf | Direction, method and declared statistical basis |
| Static puncture resistance | N under the specified method | Do not compare results from different probes as equivalent |
ASTM D4491/D4491M addresses hydraulic behavior in terms of permittivity under standard, uncompressed conditions. Flow per unit area is not permittivity: under the applicable relationship, Q/A = ψ × Δh. For illustration, ψ = 1 s⁻¹ and Δh = 0.05 m give Q/A = 0.05 m/s, approximately 73.6 US gpm/ft². Field drainage also depends on the soil and the rest of the system.
Do not assume that every heavier nonwoven becomes impermeable, or that a particular GSM guarantees a particular flow or puncture value. Obtain the actual grade’s data and compare the same methods. For detailed interpretation, use the geotextile test-report checklist.
Calculate the Quantity Before Comparing Prices
For a rectangular drain envelope, fabric width is approximately 2 × trench depth + 2 × trench width + closure overlap, before allowing for irregularities and other details. An 18-inch-wide, 18-inch-deep trench with a specified 12-inch closure overlap therefore needs 84 inches (7 ft) of width. A 6-ft width only covers the 72-inch perimeter and leaves no closure overlap.
For a 50-ft length, the 7-ft-wide envelope uses 350 ft² before end details, joins or trimming. This is a quantity example, not a recommended drain design. For flat panels, deduct every side overlap from gross roll coverage; confirm lengths and edge returns on the layout.
Separate nominal fabric mass from shipment mass. A 4 m × 100 m roll at 200 g/m² contains approximately 80 kg of fabric, excluding core and packaging. Obtain confirmed roll dimensions, roll count, gross weight and unloading requirements from the supplier.
What to Include in the Request for Quotation
- Application, destination, project specification and applicable standard editions.
- Required polymer/construction and all mechanical, hydraulic and durability requirements.
- Whether each requirement is a minimum, maximum, nominal value or other stated acceptance basis.
- Net area, proposed roll dimensions, overlap allowance and requested delivery schedule.
- Product datasheet, relevant test reports, lot traceability and agreed inspection documents.
- Currency, delivery terms, packaging, freight, unloading and any excluded charges.
Ask suppliers to identify deviations explicitly. A cheaper offer may omit testing, provide less usable area or use a different reporting basis. Confirm availability and lead time for the exact specification rather than assuming a general website figure applies.
Receiving and Acceptance
Match labels and quantities to the approved order, inspect packaging and visible damage, and record roll IDs before installation. Keep questionable material separate while the responsible parties review it. ASTM D4759 provides a conformance framework; agree sampling and acceptance rules in advance rather than accepting or rejecting an entire shipment from one improvised field test.
Preserve protective wrapping and follow the manufacturer’s storage and exposure limits. A laboratory UV exposure duration is not a calendar allowance for leaving fabric uncovered on site. To discuss a specific grade, review Jinseed nonwoven geotextile and send the application, required properties and quantity for confirmation.
