A cool concept; Additive Free Housing!

Today, and June 10th annually, is Additive‑Free Housing Day 無添加住宅の日 in Japan. It was established by Mutenka Jūtaku Co., Ltd., a company based in Nishinomiya City, Hyōgo Prefecture, known for building homes using only natural materials. The date comes from the wordplay on 6/10; "mu (6) – tenka jū (10) taku", echoing the company’s name and philosophy of creating houses free from synthetic chemicals.

The purpose of the day is to raise awareness of additive‑free housing, a concept that focuses on using natural materials such as shikkui plaster, carbonized cork, natural stone, rice glue, solid wood, and persimmon tannin. These materials are chosen to reduce the risk of sick‑house syndrome and to create living environments that are healthier and more comfortable. The company emphasizes the idea of homes that age beautifully over time, allowing residents to enjoy the natural changes in the materials.

There are some events held around this date at model home parks, that let people experience the feel and air quality of additive‑free homes. These can include hands‑on activities such as plastering workshops and handprint‑making sessions for children, helping families learn about natural building materials in an enjoyable way. The day reflects Japan’s growing interest in sustainable living, traditional craftsmanship, and environmentally conscious home design.