Field Water Penetration Failure on a Storefront: Specimen or Rig?
A field water penetration test per ASTM E1105 is scheduled on a new four-storey office building's storefront. The specification calls for 15 minutes at 300 Pa over a 1.5 m × 2.7 m area that includes one fixed light, one operable awning sash and the mullion between them. The technician erects a chamber, sprays for 5 minutes at zero pressure to wet out the specimen, then ramps to 300 Pa. The spray rack's measured water rate is 5.4 L/(min·m²) over the wetted area. At 4 minutes 20 seconds, water appears on the interior sill and runs onto the drywall return. Two facts surface during the post-test walkdown: the exterior static pressure tap sits on a standoff 3 m from the wall on the sheltered side of the building, and the chamber's sill plate rests on a rough slab, leaving a 6 mm gap that was never sealed. Wind at the time was 3 m/s with gusts. The glazing contractor says the test proves the storefront leaks and wants to begin removing mullions.
1. Is this a valid failure? List what must be ruled out before the result can be accepted.
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Water at 4 min 20 s is inside the 15-minute test period, so a genuine penetration would be a failure. But a failure is only valid if the specimen saw the specified differential and the water came through the specimen rather than the rig. Two setup defects undermine it.
The 6 mm sill gap. An unsealed gap between the chamber base and the slab is a direct path from a wetted exterior surface into the chamber. At 300 Pa that gap draws in spray and surface water film, and the water surfaces exactly where a real sill leak would appear - on the interior sill, running to the drywall return. Nothing in this test distinguishes the two.
The pressure reference. E1105 requires the differential across the specimen. An exterior tap 3 m out on the sheltered side of a building in 3 m/s gusting wind need not read the pressure on the test face; the specimen may have been driven at more or less than 300 Pa. The interior tap must also be inside the chamber but shielded from the spray and from direct fan airflow, and the tap lines must be checked for water traps and blockage.
Until the gap is sealed and the reference is corrected, the honest verdict is inconclusive, not failed. The water rate, spray coverage (no dry bands) and gauge calibration should also be confirmed on the report.
2. What is the defensible next step, and what should the report say?
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- Seal the chamber perimeter to the slab with a continuous gasket or tape and verify by feel or a smoke/leak check at test pressure that nothing passes at the base.
- Relocate the exterior reference to a shielded static probe close to the test face at the same elevation, or use a probe through the chamber wall shielded from the spray, and cross-check the differential with a second gauge.
- Confirm the interior tap is inside the chamber, away from the spray plume and out of the direct fan stream, with no water in the lines.
- Re-wet the specimen and run the full 15 minutes from the start; the clock does not resume where the first run stopped.
The report should contain both runs. The first is marked invalid, with the reason stated plainly: unsealed chamber base and a reference tap not representative of specimen pressure. The second run is the record result, with test pressure, duration, water rate, ambient wind, gauge serial numbers and calibration dates, and a photograph of the sealed base.
The report should not authorize destructive removal of mullions. The next move is a diagnostic, not a demolition.
3. Can a hose test per AAMA 501.2 be substituted for the E1105 test, or used to find the source?
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Separate the two uses.
As a substitute - generally no. AAMA 501.2 is a hose test: a nozzle at roughly 205–235 kPa, held about 300 mm from the surface, for about 5 minutes per area, with no pressure differential across the assembly. It is a diagnostic and quality-control tool. It does not reproduce the pressure-driven mechanism that E1105 is written to evaluate, and a specification that names E1105 is not satisfied by a hose test unless the specifier or authority having jurisdiction explicitly permits it.
As a locator - yes, and it is the right tool here. With the chamber removed, work the suspect details systematically: the head flashing and its end dams, the corner seals, the mullion splice gaskets, the sill pan and its end dams. The hose test localizes which detail admits water, quickly and without pressurizing anything.
The sequence that holds up: locate and repair with the hose test, then re-run the E1105 test as the acceptance test, because the acceptance criterion is written in terms of pressure and time, not in terms of a hose. Note in passing that a 5-minute hose blast is more severe than a pressure test in some respects and less in others, so a hose pass is never evidence of an E1105 pass.