A couple in Silicon Valley designed a detached ADU with the idea of creating a space for visiting grandparents, children, and eventually retirement.Instead of remodeling the existing home, they built a new 2-bedroom, 1-1/2 bathroom ADU in the backyard to achieve design freedom.The design incorporated Japanese technique 'Shakkei,' skylights for natural elements, and an accordion-style roof for visual appeal.The central bath in the ADU is designed for shared use, with warm cedar planks, earth-toned tiles, and modern fixtures for a serene experience.