ASTM E331 & E1105: Two Key Water Penetration Tests For Windows


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ASTM E331 & E1105: Two Key Water Penetration Tests For Windows

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The Link Between Water Resistance and Building Envelope

When it comes to the construction of buildings, one critical factor that cannot be overlooked is water resistance. The building envelope, which acts as a physical separator between the conditioned and unconditioned environment, plays a crucial role in keeping water out of wall assemblies.

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This is especially important in areas where wet, wind-driven rain is a common occurrence. Water penetration can lead to serious issues, including damage to materials, mold growth, and compromised structural integrity. Therefore, ensuring water resistance is essential for the long-term health of buildings and the well-being of their occupants.

Standardizing Water Resistance

To address the need for standardized testing methods to evaluate water penetration resistance, the American National Standards Institute (ANSI) developed ASTM E331 and ASTM E1105 as two key tests specifically designed for windows. These tests aim to determine the resistance of windows, skylights, doors, and curtain walls to water penetration under different air pressure conditions. By subjecting these components to rigorous testing, their performance can be assessed, and appropriate measures can be taken to ensure water tightness.

ASTM E331:

Standard Test Method for Water Penetration of Exterior Windows, Skylights, Doors, and Curtain Walls by Uniform Static Air Pressure Difference, test procedure

ASTM E331 is a widely recognized test method that determines the resistance of exterior windows, curtain walls, skylights, and doors to water penetration. This test is conducted by applying water to the outdoor face and exposed edges of the test specimen while simultaneously maintaining a higher static air pressure at the outdoor face compared to the indoor face. The purpose is to simulate realistic conditions where water is driven by wind pressure, exposing vulnerable areas of the building envelope to potential water penetration.


The test begins by constructing a test specimen wall with all the components to be tested at full size, following the same details as in an actual wall assembly. This may include the installation of an air barrier or water-resistive barrier as part of the assembly. The specimen is then installed on one side of a sealed test chamber, which is equipped with a water spray grid and a blower or compressed air system. The water is sprayed uniformly on the specimen at a specified rate, while the air pressure inside the chamber is maintained at a higher level than the indoor pressure.

During a 15-minute testing period, test technicians carefully observe the test specimen and record any points of water penetration on the inside face. The purpose is to evaluate the performance of the specimen according to specified criteria. It’s important to note that while this test method addresses water penetration through the manufactured assembly, it does not address any potential adverse effects on materials such as sealants and insulating or laminated glass.

ASTM E1105:

ASTM E1105 complements ASTM E331 by providing a standardized test method specifically designed for field determination of water penetration in installed exterior windows, skylights, doors, and curtain walls.

Standard Test Method for Field Determination of Water Penetration of Installed Exterior Windows, Skylights, Doors, and Curtain Walls by Uniform or Cyclic Static Air Pressure Difference

This test method allows for the evaluation of water resistance under realistic conditions, taking into account the variations that can occur during the installation process.


To perform ASTM E1105, a wall or fenestration is fitted with an apparatus that creates either uniform static pressure or cyclic pressure on the inside surface. A calibrated spray apparatus with nozzles on the exterior surface sprays water at a specified rate onto the installed wall assembly or fenestration. This simulates the real-world conditions of wind-driven water. The test can be conducted using either uniform pressure or cyclic pressure.

Uniform pressure involves maintaining a consistent static pressure for a period of 15 minutes. Cyclic pressure, on the other hand, involves cycling the static pressure on and off for multiple cycles, with a total testing time of at least 15 minutes. The purpose of cyclic pressure testing is to replicate conditions more realistically, as buildings are subject to varying wind pressures over time.

Both ASTM E331 and ASTM E1105 provide valuable information regarding the water-resistive performance of curtain walls and fenestrations. ASTM E331 is typically used in laboratory settings for product testing and quality assurance, while ASTM E1105 is used in the field for assessing the performance of installed fenestrations.

Differences between ASTM E331 and ASTM E1105

While both ASTM E331 and ASTM E1105 share the common goal of evaluating water penetration resistance, there are several key differences between the two test methods:

  1. Application of Air Pressure:
    1. ASTM E331 involves affixing the test specimen to the air chamber.
    2. ASTM E1105 requires affixing the air chamber to the test specimen.
    3. Additional Insight: ASTM E547 is a cyclic test during which air pressure is cycled on and off during testing.
  2. Inspection of Operable Windows:
    1. ASTM E1105 is the only water infiltration standard that explicitly describes the inspection of operable windows during testing.
  3. Testing Skylights:
    1. ASTM E331 and ASTM E547 mention and have diagrams for testing skylights.
    2. ASTM E1105 does not provide specific instructions for testing skylights.
    3. Additional Insight: ASTM E1105 is specifically written for field-testing (installed fenestrations) by using either Procedure A (uniform pressure) or Procedure B (cyclic pressure). 

By understanding these differences, professionals can select the most appropriate test method based on their specific requirements and the nature of the fenestration being tested.


Certainly, here are the key differences between ANSI (American National Standards Institute) and ASTM (American Society for Testing and Materials) based on the provided information:

Focus and Scope:

ANSI primarily focuses on providing voluntary guidance on product safety and conformity specifications across various industries within the United States.

ASTM has a more active role in creating and enforcing universal standards and regulations, with a specific focus on testing and materials.

Development Role:

ANSI does not directly develop its standards but offers guidance and frameworks. It collaborates with government bodies and industry experts to develop regulations based on international and regional needs.

ASTM actively creates and publishes new and up-to-date testing and product standards to ensure safe and quality products.

Testing Standards:

ANSI’s standards were required to conform with OSHA regulations, including those for protective footwear. However, it was replaced by a new ASTM standard for protective footwear.

ASTM, through standards like ASTM F2412 05, sets specific testing methods for protective footwear, including criteria such as impact resistance, compression resistance, and electrical hazard protection.

Industry Coverage:

ANSI is an umbrella organization that covers several industries, accrediting other organizations and approving the standards they develop, including ASTM.

ASTM plays a more active role in standards and regulations, covering a wide range of industries globally, with a focus on testing and materials.

Influence on Regulations:

ANSI’s standards were required to conform with OSHA regulations for protective PPE. However, it was replaced by a new ASTM standard for protective footwear.

ASTM works closely with ANSI in designing and governing new measures, playing a significant role in the development and enforcement of standards that ANSI approves.

Approach to Standards:

ANSI provides voluntary consensus standards that organizations can choose to adopt, covering processes and conformity systems.

ASTM, on the other hand, is more prescriptive, actively creating and enforcing standards that organizations must conform to for safe and quality products.

In summary, while both ANSI and ASTM contribute to the development of standards, ANSI offers guidance and frameworks, and ASTM takes a more active role in creating and enforcing specific testing and product standards, particularly in the realm of protective footwear.

Do Our Windows Meet ANSI Water Penetration Standards?

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Ensuring that windows and other fenestrations meet ANSI water penetration standards is crucial for the overall performance and durability of the building envelope. By subjecting these components to rigorous testing, any potential vulnerabilities can be identified, and necessary improvements can be made to enhance water resistance. This not only helps prevent water-related issues but also contributes to energy efficiency and occupant comfort.

To learn more about ASTM E331 and ASTM E1105 and their specific requirements, you can refer to the ANSI Webstore, where the standards can be accessed for further information and implementation.

In conclusion, water penetration tests for windows, such as ASTM E331 and ASTM E1105, play a vital role in assessing the water-resistive performance of exterior windows, skylights, doors, and curtain walls. By subjecting these components to controlled air pressure and water spray, their ability to resist water penetration can be evaluated. Understanding the differences between these tests and complying with the appropriate standards can help ensure the water tightness and overall performance of fenestrations in buildings.  Connect with our experts to learn more about ASTM E331 and ASTM E1105.

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