Polyethylene Film Vapor Retarder: ASTM E1745 Technical Data
This ASTM E1745 technical data explains how a polyethylene film vapor retarder should be reviewed below concrete slabs. It separates standard limits from typical references, lot-specific results, and project-confirmed values for thickness, water vapor permeance, tensile strength, puncture resistance, conditioned performance, and traceability. Final acceptance should use the submitted grade, current reports, and a representative mock-up under intended project conditions.
What This Record Measures – and What It Does Not
This record applies to flexible polyethylene sheet against soil or granular fill beneath concrete slabs. It supports ASTM E1745 classification and lot verification. It does not certify an untested grade, replace ASTM E1643 review, or cover adhesive protection, roofing waterproofing, hydrostatic pressure, or peel behavior.
Membrane Identity Before Any Number Is Read
Record resin status, layers, reinforcement, nominal and measured thickness, production date, lot code, and sample-roll identity. Total thickness normally equals film thickness because no adhesive or liner is present. Clarity, haze, and surface treatment are supplementary, not class properties.
Use multi-point measurement for average, minimum, and cross-web thickness tolerance. Thickness affects handling but cannot establish Class A, B, or C.
Classification Gate: Required Values Versus Reported Results
These limits are standard requirements, not product results. Each reported value should identify its grade, sample condition, method, and report revision.
Item | Typical Value / Reference Range | Test Method or Condition | Notes |
Construction | Declared PE structure | Lot declaration | Layers, reinforcement, sample roll |
Thickness | Confirmed average, minimum, tolerance | Calibrated multi-point measurement | Not proof of class |
New-material permeance | ASTM limit: <=0.1 perm, Classes A-C | E154/E154M Section 7 or equivalent | Report tested result separately |
Conditioned permeance | ASTM limit: <=0.1 perm per exposure | Wet/dry/soak, heat, low temperature, soil organisms | Report each condition |
Tensile strength | A >=45.0; B >=30.0; C >=13.6 lbf/in | E154/E154M Section 9; MD/TD | Strength per unit width |
Puncture resistance | A >=2200; B >=1700; C >=475 g | D1709 Method B | Other methods are supplemental |
Traceability | Lot-specific record | Grade, roll, laboratory, date, report | Typical data do not prove the lot |
Method Notes That Make Results Comparable
Compare results only when sample condition, temperature, humidity, specimen direction, thickness, unit, and method are stated.
Test Item | What It Checks | Suggested Method or Reference | Why It Matters | When To Request It |
New permeance | Initial vapor flow | E154/E154M Section 7 or equivalent | Confirms initial resistance | Qualification or formulation change |
Conditioned permeance | Post-exposure retention | Applicable E154/E154M conditioning | Initial data may hide change | When conditioned data are required |
MD/TD tensile | Directional resistance | E154/E154M Section 9 | Finds a weak direction | Qualification or periodic review |
Puncture | Falling-dart response | D1709 Method B | Indicates sharp-contact risk | Class review or high-risk work |
Thickness profile | Average, minimum, cross-web variation | D6988 guidance or equivalent | Finds thin zones | New grade or process change |
Seam mock-up | Overlap continuity | E1643-informed trial | Film compliance does not prove joints | New accessory or difficult conditions |
Reading One Result Without Ignoring the Others
Lower permeance indicates stronger vapor resistance under the stated condition but does not replace mechanical review. Classes A, B, and C share one permeance ceiling and differ mainly in tensile and puncture thresholds. Review MD and TD separately; elongation is supplementary, and puncture is method-specific.
A typical value is not lot-specific without traceable samples and reports.
Where Laboratory Data Meets the Installation Condition
Check the subgrade or granular fill, aggregate shape, reinforcement supports, traffic, seams, penetrations, temperature, humidity, sunlight, and placement sequence. Sharp contact or concentrated loads can increase damage risk despite acceptable laboratory results.
This membrane is not intended for finished glass, coated surfaces, or low-energy plastics and should not be assessed by peel adhesion, residue, gloss change, or clean removal.
One Qualification Set, One Traceable Sample Source
Use one traceable production roll for each qualification set. Record grade, lot, sample roll, conditioning, laboratory, date, result, and report reference. Retain a comparison sample where needed.
Before placement, inspect for pinholes, folds, contamination, edge damage, core deformation, and curl. Build a mock-up using the intended overlap, seam, penetration, support, and substrate. When warranted, review it initially and after 24 hours, 72 hours, and 7 days. These are project checks, not ASTM conditioning periods.
Acceptable Averages Can Still Hide Failure Risks
An acceptable average can hide a thin cross-web zone, weak transverse direction, conditioned-permeance increase, or damaged edge. Match each risk to a pre-use check.
Data Point | If Too Low | If Too High | Risk in Application | Check Before Full Use |
Permeance | Usually favorable | May exceed project limit | Moisture target missed | Method, RH, temperature, unit |
Conditioned permeance | Usually favorable | May rise after exposure | Initial result misleads | Each conditioned result |
MD/TD tensile | Higher tear risk | Stiff handling possible | Damage at folds or supports | Both directions and minimum |
Puncture resistance | Sharp-contact sensitivity | Method may differ | Hidden pre-pour holes | D1709 Method B and subgrade |
Measured thickness | Thin zones | More weight or less flexibility | Uneven durability | Average, minimum, tolerance |
Seam strength | Overlap opening | Non-comparable value misleads | Continuity loss | Actual tape, overlap, conditions |
Storage History Is Part of Data Validity
Keep rolls supported, packaged, dry, and protected from sharp objects, pressure, sunlight, heat, and standing moisture. Storage time, humidity, transport, wrapping damage, edge impact, and core deformation can affect flatness. Reinspect long-stored or long-distance shipments.
Technical Pathways for Further Review
Broader resin structures and film formats are organized under polyethylene film and sheet materials, while general dimensional references can be checked on the low density polyethylene film record. The temporary surface protection films category clarifies why adhesive construction protection should not be confused with an under-slab membrane. Documented film extrusion and quality-control capabilities support thickness profiling, retained samples, visual inspection, and production-lot traceability.
FAQ
How is ASTM E1745 class verified for a polyethylene film vapor retarder?
Use permeance, MD/TD tensile strength, D1709 Method B puncture results, conditioned data, and traceable reports for the identified grade.
Why is nominal thickness not enough?
Classification depends on tested permeance, tensile strength, and puncture resistance. Equal thickness does not ensure equal performance.
Which conditioned results should be reported?
Report applicable wet/dry/soak, heat, low-temperature, and soil-organism results separately with method, condition, unit, and report reference.
Can storage and installation change observed performance?
Temperature, humidity, sunlight, storage, transport, aggregate profile, load, equipment setting, and operator method can affect roll condition or continuity. Inspect samples before use.
