Roof Leak Inspection Day (Amamori Tenken no Hi)

What Is Roof Leak Inspection Day?

June 11th is "Roof Leak Inspection Day" (Amamori Tenken no Hi) in Japan. It was established in April 1997 by the National Rain Leak Inspection Association (全国雨漏検査協会), headquartered in Takarazuka, Hyogo Prefecture, and certified and registered by the Japan Anniversary Association. The date was chosen because it often coincides with nyūbai, the traditional seasonal marker for the start of the rainy season. The aim is to encourage people to check their buildings for leaks before the rainy season sets in, so they can avoid water damage.

Warning Signs of Roof Leaks to Check Before the Rainy Season

Leaks often start from damaged roofs, cracks in exterior walls or balconies, or gaps around window frames. If left unaddressed, they can lead to rotting wooden beams and posts, rusting metal parts, and mold. Before the rainy season hits in earnest, it's important to check the roof, ceilings, exterior walls, and around windows and sashes.

• Stains or discoloration on ceilings or walls
• Moisture or mold around window frames and sashes
• Cracks in balcony floors or clogged drains
• If you can access the attic, check insulation material for dampness or discoloration

Where Do Leaks Come From?

Leaks don't always come from the roof. Rainwater can also get in through cracks in exterior walls, gaps between window frames and waterproof sheeting, or skylights. Water stains often appear far from where the water actually enters, which is what makes leaks so hard to trace. Noticing small changes, such as ceiling stains or peeling wallpaper, before water actually starts dripping is the key to early detection.

Technology for Finding Leaks

The National Rain Leak Inspection Association uses a test liquid that glows under ultraviolet light. By pouring the liquid over suspected areas and tracing the glowing marks with a special light, inspectors can identify the path of the water and the source of the leak.

Consult a Professional

Trying to fix a leak yourself based on guesswork carries the risk of missing the root cause, and climbing onto a roof also carries the risk of falling. Hiring a professional leak inspector to pinpoint the cause before repairs helps your home last longer. As the rainy season approaches, take a moment to think about inspecting your home.