
The Storm Hose Test: Safely Recreating Wind-Driven Leaks at Home
Wind-driven rain can make a perfectly good roof leak. If you have stains that only appear during sideways rain, a controlled “storm hose test” can help confirm where water is entering. This article explains how to stage a safe, repeatable test that mimics crosswinds without damaging shingles or flooding your attic, and when to pivot to professional roof repair if your findings point to a failed detail. If your roof is steep, high, or aged, do not attempt this test—call a licensed professional. We cover safety, tools, step‑by‑step procedures, what to watch for, and when to call it and bring in a pro. Important: A hose test should be gentle and methodical. Never use a pressure washer. Never spray into roof penetrations or under shingle laps. Stop immediately if water appears indoors. When a hose test makes sense You notice drips only during gusty storms, not during calm showers. Interior stains trace back to a specific wall, chimney, dormer, or ridge line. You have already ruled out plumbing and HVAC condensation as sources. You want documentation to support a repair plan or insurance discussion; pairing photos with our guide on how to find a roof leak speeds decisions and keeps the scope focused. When not to test Active electrical hazards near the suspected area. Severe weather in the forecast. Testing is not an emergency patch. Roofs that are unsafe to walk due to pitch, height, or condition. Recently installed roofs that still fall under a contractor’s workmanship warranty. Call the installer first to avoid disputes. Tools and helpers Garden hose with an adjustable spray nozzle that can deliver a wide, soft pattern. A second person to manage the hose or monitor the interior. Painter’s tape and a notebook for time‑stamped notes. Smartphone for photos and short clips. Ladder with stabilizers and non‑marring feet. Personal protective equipment: shoes with grip, gloves, and eye protection. Optional: moisture meter and a headlamp for attic checks. Safety first Work with a partner and set a verbal check‑in every few minutes. Protect electrical fixtures and keep water away from service masts and open junction boxes. Use a low‑pressure, wide fan setting. You are recreating rain, not washing the roof. Place the ladder on stable ground and maintain three points of contact. Do not attempt this test on high, steep, or aged roofs. Always consult a licensed roofing professional if you are unsure. The logic behind a storm hose test Wind‑driven leaks often come from reversed overlaps or small gaps that only open under lateral pressure. A good test introduces water from low to high and from least intrusive to most, while the interior is monitored in real time. By moving in short zones and logging times, you can triangulate the exact entry point and decide whether the fix is minor or needs a larger roof replacement or roof installation scope during a reroof. Common targets that respond to crosswinds Roof‑to‑wall joints at sidewalls and dead valleys. Kick‑out flashing locations at gutter returns. Ridge vents without external baffles (see our primer on balanced roof ventilation). Chimney shoulders and counterflashing transitions. Skylight corners and curb flashings. Pipe boots with cracked collars. Valleys with debris dams near the eave end. For research-backed diagrams on how wind-driven rain finds its way into roof assemblies (especially at roof-to-wall edges), the U.S. Department of Energy’s Building America Solution Center has a clear primer on step and kick-out flashing that pairs well with this test: Step- and Kick-Out Flashing at Roof/Wall Intersections. Setup checklist Walk the yard. Remove debris that could snag the hose. Clear gutters near the test area so water does not back up; here is a quick refresher on how to clean your gutters before you start. Inside the home, expose ceilings or attic under the suspect zone. Lay towels and a plastic drop cloth. Assign roles: one person outside with the hose, one inside with a light. Start a shared timer on your phones. Step‑by‑step procedure 1) Start low and slow Stand below the test area. Using a wide fan, wet the shingles two to three courses above the eave for three minutes. Keep the nozzle at least 3–4 feet away from the surface and aim as a light sideways rain would. The interior partner watches for drips or new stains and notes the time. 2) Move laterally across the lower courses Advance along the eave line in three‑minute segments, overlapping each section by a foot; if overflow is part of the issue, plan a follow‑up gutter check as well. If no leaks appear, move one course higher and repeat. 3) Focus on transitions At each valley, sidewall, vent, or flashing change, test in short bursts. Keep the spray from entering under shingles. At a roof‑to‑wall joint, test the field first, then the step flashing zone, then the kick‑out; if you confirm entry here, our residential roofing services team can rebuild the sequence correctly. Mark the clock for each segment. 4) Work upslope toward the ridge If lower sections do not trigger a leak, move upslope one course at a time. For ridge vents, stand slightly off the ridge and direct a soft, lateral mist across the cap, never directly into the vent opening; severe staining or cap damage may warrant storm damage repair. 5) Pause and inspect After each segment, the interior partner checks the attic or ceiling. If moisture appears, stop adding water and switch to containment while you schedule a free inspection. Note the segment name and time stamp. 6) Confirm and repeat lightly If one segment likely triggers the leak, repeat it with a brief, gentle spray to confirm. Multiple small confirmations are better than one long flood that soaks materials and confuses the result. Interpreting results Immediate drip within one to two minutes suggests a leak near the surface or a direct path, such as a missing shingle, nail hole, or lifted flashing edge. Delayed dampness after five to ten minutes points to capillary travel behind siding or along underlayment laps. Spread







