Exterior, House Building Type, and Metal Siding Material In Boulder's aptly named Wonderland Hill neighborhood, deer and even mountain lions occasionally come down from the woods to scout the domestic scene, but the most common wildlife sighting on the tree-lined streets is a profusion of toddlers in off-road strollers. To make space for the local baby boom, many older one-story homes have had their pops topped. When Rob Pyatt and Heather Kahn were ready to expand on their 900 square feet, however, their foundation couldn't support a second floor, so Pyatt, an architecture student with a green building background, devised an alternative. His box-shaped addition is the modern kid on the block, with distinctive corrugated-metal and wide-plank cladding. Behind the facade, uncommon materials share a common story with the neighborhood: Of design decisions driven by a desire to keep the next generation—and the planet—healthy and safe.  Photo 3 of 9 in Post Bale