Verification Facility and Public Experiment Viewing for 'Underfloor Flooding Countermeasure Material' (May 28 in Soka City, Saitama)

Denka Astec Co., Ltd. (President: Kazuyuki Goto, Headquarters: Minato-ku, Tokyo), in conjunction with the Water Hazard Prevention Month in May, will host a demonstration facility tour and a report on the theme of 'Disasters and Water' on Thursday, May 28. The event will feature 'Dam Armor,' Japan's first* phase-free underfloor flooding countermeasure material, which was developed following a dialogue with Mr. Takeji Kodama, the representative director of the Disaster Prevention Housing Research Institute, a leading authority on disaster-prevention housing research who has investigated large-scale disaster sites both in Japan and overseas.

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The 'Reality of Underfloor Flooding' That Fire Insurance Can't Protect Against, Exceeding Imagination

A Public Experiment of 'Dam Armor,' the Sill Flashing that Successfully Prevents Underfloor Flooding ================================================================================

In recent years, in addition to the rainy season and typhoons, an increase in localized guerrilla rainstorms has exacerbated flood damage to homes.

Underfloor flooding, in particular, accounts for the majority of housing damage, yet it is often not covered by fire insurance below a certain water level, becoming a major burden for rebuilding lives.

In response to this situation, a new approach to housing disaster prevention was born from discussions with Mr. Kodama, who has witnessed numerous sites where 'people cannot act as they would like when faced with a major disaster.' This approach incorporates the 'phase-free' concept of not distinguishing between normal times and disaster times.

This product focuses on the often-overlooked 'sill flashing' as a flood path into a house. It is a new mechanism that prevents underfloor flooding by maintaining ventilation during normal times and automatically blocking the ventilation path during flooding. Based on our nearly 70 years of experience in gutter manufacturing and our expertise in rainwater collection and drainage, we have pursued a form of disaster prevention based on the premise that 'people cannot move during a disaster,' and have succeeded in developing a special material that prevents flooding from the sill flashing, which is said to be the largest source of underfloor water ingress.

Comparison between standard sill flashing and sill flashing with flood prevention function

What is sill flashing?

It is a flashing installed between the outer wall and the foundation to prevent rainwater from entering the foundation. In ventilated wall construction, it also serves as the starting point of the ventilation layer, drawing in air to release moisture from within the walls. It is a building material installed around the entire perimeter of the boundary between the outer wall and the foundation of a house and is used in many wooden houses. However, while it serves as a vent to draw in air and release moisture in daily life, it becomes a major cause of underfloor flooding damage as it becomes a pathway for water to enter under the floor when water accumulates due to heavy rain.

What is sill flashing

Differences and Uniqueness Compared to Conventional Flood Control Products

○ Conventional Flood Control Products ・It is necessary to install sandbags or water stop plates from the outside of the house to block water during an inland flood. ・There is a risk that residents cannot enter the house after installing the water stop plate. ・Although there were entrance doors with flood prevention functions, there were no products that could prevent flooding into the house from the sill flashing. ・Even with flood control products, in many cases, people do not know how to use them in an emergency, or they forget their existence in a panic and end up not using them. ・A storage place is required to store the flood control products.

Sandbags and water stop plates to prevent underfloor flooding

○ Our Developed Flood Control Material, Dam Armor ・A phase-free product that, once installed, provides flood protection without any action, both in normal and emergency times. ・Realized the first flood-proof sill flashing in Japan. ・The special expansion material inside Dam Armor (flood-proof sill flashing) absorbs water during inland floods, automatically expanding to prevent underfloor flooding. ・Even after being submerged once, it can be prepared for flooding again by replacing the special expansion material inside. ・It can roughly protect against underfloor flooding up to a height that would not be covered by fire insurance. ・An experimental verification device has been completed in Soka City, Saitama Prefecture.

Sill flashing with flood prevention function, Dam Armor

Development Background

・In recent years, localized heavy rains have increased by about 1.4 times compared to 30 years ago, and housing flood damage has occurred in over 15,000 households per year. ・Underfloor and above-floor flooding account for 79% of all housing flood damage. ・Underfloor flooding of less than 45cm is often not covered by fire insurance, and even if it is, the repair costs are often not fully covered. Despite the significant time, money, and mental burden of restoring a flooded underfloor area, there were no concrete countermeasures.

Trends in the frequency of heavy rain

・Among the assumed flood points of a house (entrance door, back door, sashes, sill flashing, drains), we recognized the urgent need to develop a flood control product for the sill flashing, which is the source of the largest amount of water ingress and where flooding occurs in the initial stage of a disaster. ・As a result of on-site investigations in flood-stricken areas, we observed situations where people were prepared but could not install the measures in time and were unable to take action when the disaster struck.