This guide is a practical reference for selecting non-woven geotextile fabric by specification. Whether you need to match a DOT project requirement, check a fabric against your state’s requirements, or see what each weight delivers, this is your lookup resource. The values below come from Pro Fabric Supply’s published spec sheets.

How to Read Each Spec

Weight (oz/yd²)

Ounces per square yard (ASTM D5261). Heavier fabric has more fiber per unit area, which generally means higher strength and puncture resistance, smaller openings, and somewhat lower flow. Weight is the primary selection criterion for most non-woven applications.

AOS (Apparent Opening Size)

Tested by ASTM D4751 and expressed as a US Standard sieve number, often with the equivalent opening in millimeters. Larger sieve number = smaller openings = finer filtration. AOS #50 corresponds to 0.297 mm, #70 to 0.212 mm, and #100 to 0.15 mm. Unlike the strength values, AOS is reported as a maximum — the fabric’s openings should be no larger than the listed size.

Matching AOS to Your Soil

The finer the soil, the smaller the openings need to be. Sandy and gravelly soils can use more open fabrics, while silts and clays call for smaller openings. On specified work, the maximum AOS and minimum permittivity come from your state or project requirements; for engineered designs, the engineer compares AOS to the soil’s gradation.

Permittivity (sec⁻¹)

The rate at which water flows through the fabric per unit of head, tested by ASTM D4491. Higher numbers mean more water passes through. Required minimums depend on the soil and the application, and specified work lists its own value. Spec sheets often list water flow rate (gpm/ft²) from the same test.

Grab Tensile (lbs)

The peak load a fabric strip withstands in a grab tensile test (ASTM D4632). Higher values mean the fabric better survives aggressive installation. Grab tensile is one of the headline values in most highway geotextile specifications, alongside tear and puncture strength.

Grab Elongation (%)

How much the fabric stretches at failure in the same ASTM D4632 test. Non-woven geotextiles typically elongate 50% or more, and specifications often set different strength requirements for higher-elongation (non-woven) and lower-elongation (woven) fabrics.

Trapezoid Tear (lbs)

Resistance to a tear spreading once started (ASTM D4533). Highway specifications commonly include a tear requirement.

CBR Puncture (lbs)

Resistance to a blunt plunger pushed through the fabric (ASTM D6241). Higher values mean the fabric better survives aggregate placement, which matters most with large or angular stone. Some older specs and sheets also list pin puncture (ASTM D4833), a different test with much lower numbers.

Spec Reference: 4 oz Through 32 oz

Minimum average roll values (MARV) from Pro Fabric Supply’s published spec sheets. AOS is a maximum value. Permittivity and water flow are not listed on the 20 oz and 32 oz sheets, which are erosion control grades.

For project submittals, use the spec sheet for the specific fabric you order.

AASHTO M288 Class Designations

AASHTO M288 is a geotextile specification for highway applications such as subsurface drainage, separation, stabilization, and erosion control. It sorts fabrics into survivability classes — Class 1 is the most robust, Class 3 the least — so the fabric holds up during installation. Each class sets minimum values for properties like grab tensile, tear, and puncture strength, and the specification also addresses AOS and permittivity for some applications.

States adopt M288 in different ways: many reference it directly, others modify the values or use their own geotextile specifications, and the standard itself is revised periodically. Always confirm the required class and property values with your state DOT specification and the project special provisions, then compare each value against the spec sheet for the fabric you plan to order.

Spec vs. Application-Based Selection

When application-based selection works (most common)

For residential and standard commercial projects, selecting by application type is usually adequate and simpler:

• French drain in sandy soil → 4 oz non-woven
• French drain in clay soil → 6 oz non-woven
• Retaining wall drainage → 4–6 oz non-woven

When to verify against published specs

• A DOT project submittal requires documentation that the fabric meets your state’s specified class or property values
• The engineer of record specifies minimum property values in the project documents
• You are comparing two products at different price points to confirm equivalent performance
• Unusual soil conditions call for a tighter AOS than standard weight selection provides

Project-to-Spec Guide

This guide is for general reference. Where a project has an engineer or written specification, those requirements govern fabric selection.