ASTM E1105 Explained: Window Water Penetration Testing Standards and What They Mean for Your Project
Understand the testing procedures, pressure levels, regional requirements, and how ASTM E1105 results drive design decisions and remediation strategies for windows, curtain walls, and storefronts.
What is ASTM E1105?
ASTM E1105 (Standard Test Method for Field Determination of Water Penetration of Installed Exterior Windows, Skylights, Doors, and Curtain Walls) is the industry standard for measuring whether installed windows and curtain walls actually prevent water intrusion. Unlike laboratory tests that evaluate products in controlled conditions, ASTM E1105 tests real installations in real conditions—subject to actual building movement, substrate variations, and field installation quality.
This is the critical distinction: AAMA (American Architectural Manufacturers Association) standards test windows in laboratories under ideal conditions. ASTM E1105 tests windows as they're actually installed on your building. The results often differ dramatically.
🔍 The Problem
Many windows and curtain walls pass laboratory testing but fail field testing because field conditions differ: movement, thermal cycling, substrate variations, and installation quality all differ from lab conditions. ASTM E1105 is the only test that validates actual building performance.
How ASTM E1105 Testing Works
The Testing Procedure
ASTM E1105 uses pressurized water application to simulate wind-driven rain. The test apparatus applies water to the exterior of the window or curtain wall while simultaneously applying air pressure differential (simulating wind force). The test operator monitors whether water penetrates into the building.
Testing Levels: Understanding Pressure Requirements
ASTM E1105 defines testing in pressure "classes" that correspond to wind speeds and rain intensity. Different building types and locations require different test levels:
| Test Level | Pressure (PSF) | Equivalent Wind Speed | Typical Applications |
|---|---|---|---|
| Class A | 0.3 psf | ~30 mph | Protected residential areas |
| Class B | 0.5 psf | ~40 mph | Standard residential |
| Class C | 1.0 psf | ~55 mph | High-rise and coastal |
| Class D | 1.5 psf | ~70 mph | Hurricane and severe wind zones |
| Class E | 2.0 psf+ | ~85+ mph | Extreme exposure locations |
Regional building codes dictate which test level is required based on wind speed maps and rain intensity data. California coastal areas, for example, typically require Class C or higher. Hurricane zones require Class D or E.
Mockup vs. Field Testing
ASTM E1105 testing occurs in two phases:
- Mockup Testing: Before construction begins, a representative sample (full-scale section) is tested to validate the design. Mockups are built in controlled environments and tested under ideal conditions.
- Field Testing: During or after construction, actual installed windows are tested on the building to verify that field installation quality matches mockup performance.
Many projects fail field testing even though they passed mockup testing. This reveals installation quality problems that must be corrected before final acceptance.
Regional Requirements: How Your Location Affects Testing
Building codes across the West vary in ASTM E1105 requirements:
California
California Building Code (CBC) requires ASTM E1105 testing for windows in new construction and alteration projects. Coastal areas (within 1 mile of ocean) typically require Class C minimum; inland areas require Class B. Architects and engineers must specify the required test level in construction documents.
Arizona & Nevada
Arizona and Nevada building codes require ASTM E1105 testing for commercial buildings and high-rise residential. Testing levels typically range from Class B (protected areas) to Class C (exposed/high-rise). Desert monsoon season creates significant wind-driven rain conditions that justify higher test levels.
Idaho & Utah
Idaho and Utah building codes typically require Class B testing for most installations, with higher requirements for buildings in mountain passes or at higher elevations where wind speeds are greater.
Oregon & Washington
Pacific Northwest regions require ASTM E1105 testing, with Class B as minimum for coastal areas and Class C for exposed locations. Heavy rainfall combined with wind creates significant water penetration risk.
What Test Level Does Your Project Require?
ACE can determine your project's required test level based on location, exposure, and building code requirements, then coordinate testing with FGIA-accredited laboratories.
Get Your Testing RequirementsInterpreting ASTM E1105 Results
Passing vs. Failing
ASTM E1105 has a clear pass/fail criterion: zero water penetration. Even a single drop of water entering the building means the test has failed. This zero-tolerance standard reflects the reality that water intrusion creates problems that cascade over years—allowing even small amounts of water is unacceptable.
What If Testing Fails?
When field testing fails, the project team must:
- Identify the failure location: Test operators document exactly where water entered the building
- Understand the root cause: Was it sealant failure? Improper installation? Design error? Material defect? The root cause determines the fix
- Design a correction: Fixes might include re-sealanting, adding additional sealant, adjusting drainage, or redesigning details
- Test the correction: Re-test the area to confirm the fix works before accepting the installation
Comparing Results to Product Specifications
Window and curtain wall manufacturers provide specifications for testing performance. However, manufacturing specs are often based on laboratory testing (AAMA standards) under ideal conditions, not field testing (ASTM E1105) under real conditions. Your actual field test results are more meaningful than manufacturing specifications.
ASTM E1105 vs. AAMA Standards: Critical Differences
AAMA standards (501/502/503) test windows in laboratories under controlled conditions. ASTM E1105 tests actual installations in field conditions. This distinction is crucial:
| Aspect | AAMA Laboratory Testing | ASTM E1105 Field Testing |
|---|---|---|
| Environment | Controlled laboratory | Real building conditions |
| Substrate | Ideal surfaces, clean | Actual building materials with variations |
| Installation | By trained technicians | By field crews under schedule pressure |
| Building Movement | Simulated or none | Real thermal and structural movement |
| Pass/Fail Criteria | Product-dependent | Zero water penetration (zero tolerance) |
Many projects have passed AAMA testing but failed ASTM E1105 field testing. This is not unusual—it reflects the reality that field performance differs from laboratory performance.
When to Test: Mockup, Interim, and Final Testing
Pre-Construction Mockup Testing
Before construction begins, test a full-scale representative sample to validate the design. Mockup testing reveals design problems while they can still be corrected without disrupting the construction schedule.
Interim (Progress) Field Testing
Test completed sections periodically during construction rather than waiting until the end. This allows discovery and correction of installation quality problems while work is still accessible. If final testing reveals problems, you'll have identified and fixed them along the way.
Final Field Testing
Comprehensive testing of all windows and curtain wall areas before project completion. This validates that the entire installation meets specifications and building code requirements.
✓ Best Practice
Plan for three testing phases: mockup (validates design), interim (validates installation quality during construction), and final (validates complete system). This approach costs more upfront but prevents expensive failures or delays at project completion.
Frequently Asked Questions
Do all windows need ASTM E1105 testing?
Building codes require testing for new construction and major alterations in most states. Some residential projects may not require testing depending on location and building type. Check your local building code or consult with your architect.
Why do some windows fail ASTM E1105 testing if they passed AAMA testing?
AAMA testing uses ideal laboratory conditions with clean, flat substrates, no building movement, and expert installation. ASTM E1105 tests actual field conditions with real substrates, building movement, and actual field installation quality. Field conditions are more challenging.
How long does ASTM E1105 testing take?
Mockup testing typically takes 1-2 weeks from sample delivery to results. Field testing timing depends on access and weather; testing cannot occur during rain. Budget 2-4 weeks for field testing coordination and completion.
What happens if field testing fails?
Failed tests must be investigated to identify the cause, corrected, and re-tested. Re-testing typically takes 1-2 weeks. Budget schedule contingency for potential re-testing.
Can ASTM E1105 testing be used to diagnose existing leaks?
Yes. Testing can be performed on existing buildings to verify whether windows or curtain walls are actually penetrating water and to confirm that repairs have resolved the problem.
Who can perform ASTM E1105 testing?
FGIA-accredited testing laboratories are qualified to perform this testing. Accreditation ensures testing is performed to standard procedures and results are legally defensible.