Geotextiles for Waterproofing Detailed explanation

Geotextiles are versatile geosynthetic materials used in many civil engineering and construction applications. When used for waterproofing, geotextiles provide a water barrier while still allowing water vapor transmission. This makes them an ideal material for below-grade waterproofing.

Geotextiles are available in different forms including woven, nonwoven, knitted, and composite. The type of geotextile selected depends on the application and performance requirements. This article provides a comprehensive overview of using geotextiles for below-grade waterproofing.

Geotextile Composition

Geotextiles are made from synthetic polymer fibers such as polypropylene, polyethylene, polyester, or polyamide. The table below shows the typical composition of different geotextile types:

Geotextile TypeTypical Polymer Fibers Used
WovenPolypropylene, Polyester
NonwovenPolypropylene, Polyester
KnittedPolypropylene, Polyester, Polyamide
CompositeCombination of above polymers

The polymer fibers provide strength, chemical resistance, and long-term durability in ground conditions. Manufacturing methods like needle punching, heat bonding, and resin treatment produce a range of physical characteristics for different applications.

geotextile for waterproofing

Geotextile Properties

Geotextiles exhibit certain key properties that make them suitable for below-grade waterproofing.

Minimum grab tensile strengthProvides resistance against installation damage and in-situ soil stresses
Trapezoidal tear strengthResistance against puncture and tearing
Apparent opening sizeActs as a filtration layer while allowing water passage
Water permeabilityAllows water drainage while blocking soil passage
Chemical resistanceLong-term durability against soil chemicals, microbes, and pH
UV resistanceAbility to withstand sunlight exposure during installation

Proper geotextile selection ensures required performance levels for these properties. Testing is done as per standardized test methods.

Geotextile Applications for Waterproofing

Geotextiles are used in below-grade waterproofing systems for:

  • Retaining walls
  • Basements
  • Tunnels
  • Earth-covered structures
  • Landfill liners
  • Ponds, canals
  • Foundations
  • Parking garages

They provide waterproofing, drainage, and protection from moisture damage and hydrostatic pressure buildup.

Geotextile Types for Waterproofing

The table below compares different geotextile types and their typical use in waterproofing applications:

Geotextile TypeKey PropertiesTypical Waterproofing Applications
NonwovenHigh water flow capacity, moderate puncture resistanceRetaining walls, foundation walls
WovenHigh tensile strength, tear resistanceLandfill liners, harsh installation conditions
CompositeCombines properties of woven and nonwovenTunnels, below concrete slabs
Bentonite clay geotextileSelf-sealing abilityBelow-grade walls, secondary water barrier

Project specifications dictate which geotextile type provides the required performance level most cost-effectively.

Geotextile Specifications

Geotextiles used for below-grade waterproofing must meet minimum material specifications as per standards like ASTM D4439, ASTM D5261, and ASTM D6707.

ParameterSpecification Requirements
Grab tensile strength400-1200 lbs, depending on application
Trapezoidal tear strength100-250 lbs
Apparent opening size≤ 0.3 mm for fine soils
Permeability0.5 – 15 gallons/min/ft2
UV resistance50-70% strength retained after 500 hours

Other key specifications include geotextile roll weight, roll dimensions, and polymer material requirements.

Popular Geotextile Products

Many reputable manufacturers offer geotextile products for waterproofing uses. Some popular options include:

ProductKey Features
Mirafi 140NVersatile nonwoven for walls and foundations
Carthage Mills FX-40HSHigh strength woven with cross-machine direction
Stratatex ST142Composite geotextile for harsh installation
CETCO SeamGripPolypropylene bentonite clay waterproofing membrane

Pricing depends on product specifications and order quantity. Contact manufacturers for current cost details.

geotextile for waterproofing

Geotextile Handling and Storage

To maintain geotextile integrity, proper handling and storage is essential:

  • Avoid excessive ultraviolet light exposure
  • Prevent contact with chemicals, flames, sparks
  • Limit storage period to less than 6 months
  • Store rolls horizontally and avoid stacking over 3 rolls high
  • Use fabric straps instead of cables or chains
  • Avoid dragging rolls and sharp handling equipment

Cover geotextiles with opaque protective sheeting on site. Follow any additional handling guidelines from the manufacturer.

Geotextile Installation Safety

Workers must take safety precautions during geotextile installation:

  • Use correct PPE like gloves, boots, hard hats
  • Follow safe lifting techniques for heavy rolls
  • Prevent falls into excavations with barricades
  • Allow only trained operators to use installation equipment
  • Watch for underground utilities and electrical lines
  • Stop work in high winds or storms

Adequate ventilation should be provided in enclosed areas. Requirements per OSHA standards must be met.

Inspection and Testing

Geotextiles must be inspected upon delivery and tested before installation:

Inspection ChecksTest MethodsAcceptance Criteria
Proper product typeASTM D4632 – Grab tensile testPer project specification
No defects or damageASTM D4533 – Trapezoid tear testPer project specification
Roll labels and product IDASTM D4751 – Apparent opening sizePer project specification
Storage conditionsASTM D4491 – Water permeability testPer project specification

All geosynthetics testing must be done in an accredited lab. Defective or deficient materials must be replaced.

Installation Procedures

Correct installation procedures are vital for geotextile waterproofing function:

  • Prepare smooth surface for geotextile placement
  • Unroll geotextile smoothly without folds or wrinkles
  • Overlap seams and joints per specification
  • Use adhesive, pins, or soil backfill to hold in place temporarily
  • Avoid driving directly on geotextile with vehicles
  • Place protection layer like sand over geotextile before backfilling
  • Repair any damaged sections immediately

Follow manufacturer guidelines and project specifications closely.

Long-Term Performance

When properly selected and installed, geotextiles provide reliable below-grade waterproofing performance:


  • Allow groundwater drainage unlike plastic membranes
  • Resist chemical and microbial degradation
  • Withstand soil pressure and movement
  • Long design life exceeding 50 years


  • Can be damaged by excess site disturbance
  • Proper overlaps and sealing is required at seams
  • Not recommended for high water velocity applications

Regular inspections help detect any deficiencies for repair. Overall, geotextiles present excellent long-term value for below-grade waterproofing.


Geotextiles present an excellent waterproofing solution for below-grade structures. Their filtration capability manages groundwater contact while allowing vapor transmission. A range of geotextile products with specific performance properties are available. Following proper design, handling, installation, and inspection procedures is critical. Geotextile waterproofing provides long-term durability, performance value, and safety across many construction applications.


Q: How does geotextile provide waterproofing compared to other materials?

A: Geotextiles waterproof by blocking passage of fine soil particles while allowing water flow. This is different from plastic sheets that act as total water barriers. The geotextile filtration mechanism prevents hydrostatic pressure buildup.

Q: What type of soil conditions are unsuitable for geotextile waterproofing?

A: Geotextiles are not recommended for soils with high percentage of coarse gravel or sharp rocks that may damage the geotextile. High groundwater flow velocities above 15 gallons/min/ft2 are also unsuitable.

Q: How are seams and overlaps sealed in geotextile waterproofing applications?

A: Seams can be sealed by adhesives, thermally bonded strips, or bentonite fillers. Typical overlaps are 6-12 inches. Soil backfill also helps seam sealing.

Q: Does geotextile waterproofing require maintenance?

A: Minimal maintenance is needed if installed correctly. Regular inspections help detect defects for repair. Maintenance access should be provided to critical areas.

Q: How long does geotextile waterproofing last compared to other methods?

A: Properly installed geotextiles can have 50+ year design life. This exceeds plastic membranes and bituminous coatings. Longevity depends on polymer resistance to soil environment.

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