Performance

What Is ASTM E283 Testing, and Why Does It Matter for Mail Slots?

A door lets people pass through, and it holds back air. A window lets in light, and it holds back air. A mail slot lets in mail, and it should hold back air too. That is the job all three share, even though a mail slot is rarely tested to prove it actually does that job. ASTM E283 is the standard laboratory method for measuring how much air moves through a window, door, or similar opening, under a controlled amount of pressure, similar to wind pushing against a house.1 The Brass-Seal Forged Brass Mail Slot System is among the first mail slots independently tested to ASTM E283, with results verified by Intertek, an internationally accredited testing laboratory.

What the Standard Actually Measures

Every door, window, or opening in a home is expected to hold back a certain amount of air under normal wind and pressure conditions. ASTM E283 tests this by sealing a specimen into a test chamber, then creating a set pressure difference across it, in BOTA's case 75 Pascals, roughly comparable to a 25 mph wind hitting the face of a building directly. Air movement through the specimen is then measured in liters per second per square meter, or the imperial equivalent, cubic feet per minute per square foot.

The lower the number, the less air is moving through the assembly. ASTM E283 sets a maximum allowable rate for a component to pass. Anything below that line is a pass. How far below the line an assembly performs is what separates a bare pass from strong, verifiable performance.

Why This Testing Matters Just as Much for a Mail Slot as a Door or Window

Doors and windows are engineered from the outset to seal against air movement, so ASTM E283 testing on a finished door or window assembly mostly confirms what the design already intended. Passing is expected, not notable.

A mail slot sits in a different position. It is an opening cut into an already sealed door, sized to let mail through. Once that opening exists, the mail slot hardware itself is the only thing left holding back air at that spot, since the door no longer can on its own. Most mail slots on the market are stamped sheet metal or plastic components sold as accessories, without any independent verification of how much air actually moves through them. Homeowners with an older or standard mail slot often already notice a whistling sound, or a spot near the mail slot that feels noticeably less sealed than the rest of the door. That felt experience is usually the only signal available, since testing data for this specific product has rarely existed to confirm or explain it.

This is why ASTM E283 testing on a mail slot is worth paying attention to in a way it typically is not for doors and windows generally. It is not a formality. It measures and verifies one of the few places in a home that homeowners can often sense is a weak point, even before they have data to explain why.

The Brass-Seal Results

The Brass-Seal was independently tested by Intertek to ASTM E283/E283M-19 at a 75 Pascal pressure differential, in three configurations: the Exterior unit alone, the Interior unit alone, and the two units paired together spanning the full depth of the door. Report No. T4376.01-301-44-R1.

ASTM E283 maximum allowable rate: 1.5 L/s/m2 (0.3 cfm/ft2)

Configuration Infiltration Exfiltration Result
Brass-Seal Interior (standalone) 0.6 L/s/m2 (0.12 cfm/ft2) 0.3 L/s/m2 (0.06 cfm/ft2) PASS, 60% below the allowable limit
Brass-Seal Exterior (standalone) 1.0 L/s/m2 (0.20 cfm/ft2) 0.6 L/s/m2 (0.11 cfm/ft2) PASS, 33% below the allowable limit
Paired System (Exterior and Interior) 1.0 L/s/m2 (0.20 cfm/ft2) 0.6 L/s/m2 (0.11 cfm/ft2) PASS, 33% below the allowable limit

All three configurations passed. A 33 percent margin below the allowable limit means the assembly let through roughly a third less air than the standard requires to pass at all. A 60 percent margin means less than half the allowable air movement passed through. These are not pass or fail alone, they show how much performance room exists beyond the minimum.

The full Intertek report, including test chamber conditions, specimen drawings, and complete methodology, is available upon request. Contact info@blockouttheair.com.

What This Means for Specification

A documented ASTM E283 result gives architects something concrete to point to, rather than relying on an unverified claim from a manufacturer. Architects call this kind of proof a submittal, the official paperwork used to show a product meets a required standard before it is approved for use on a project. It also connects to two widely used green building frameworks:

The Brass-Seal result provides documentation that a commissioning team can cite in support of these credits. It does not itself qualify a project for LEED or WELL certification, since those credits are earned at the project level, not the product level.

CSI MasterFormat is the standard numbering system architects, contractors, and builders use to organize and reference building products by category.4 Under CSI MasterFormat, mail slot hardware falls under Section 08 71 00, Door Hardware.

Frequently Asked Questions

What is ASTM E283?
ASTM E283 is a standardized laboratory test method that measures the rate of air leakage through a building component, such as a window, door, or door hardware assembly, under a set pressure difference.

Does a tested mail slot help a project earn LEED or WELL credits?
A verified test result gives a commissioning team documentation to cite in support of relevant credits, such as LEED v4.1 EQ Compartmentalization or WELL v2 Air Infiltration Management. It does not by itself qualify a project for certification, since credits are awarded at the project level.

How is a mail slot tested for air leakage?
The mail slot is sealed into a test chamber and a controlled pressure difference is created across it, replicating wind pressure on a building face. Instruments measure how much air moves through the assembly at that pressure, expressed in liters per second per square meter or cubic feet per minute per square foot.

Is the Brass-Seal the first mail slot tested to ASTM E283?
The Brass-Seal is among the first mail slots independently tested to ASTM E283, with results verified by Intertek.

Can I see the full Intertek report?
The full report is available upon request. Contact info@blockouttheair.com.

Sources

  1. ASTM International. ASTM E283/E283M-19: Standard Test Method for Determining Rate of Air Leakage Through Exterior Windows, Skylights, Curtain Walls, and Doors Under Specified Pressure Differences Across the Specimen.
  2. U.S. Green Building Council. LEED v4.1 Residential Single Family Homes, January 10, 2020. EQ Prerequisite: Compartmentalization, p. 57. usgbc.org/sites/default/files/LEED_v4.1_Single_Family_Draft.pdf
  3. International WELL Building Institute. WELL v2, Air Infiltration Management. standard.wellcertified.com/air/air-infiltration-management
  4. Construction Specifications Institute. MasterFormat. csiresources.org/standards/masterformat

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