The frames of the traditional homes are made with massive, interwoven red pine ("akamatsu" 赤松) or southern Japanese hemlock ("tsuga" 栂) logs for horizontal beams and squared-off chestnut ("kuri" 栗) for vertical beams. All are connected through traditional craftsmanship without nails, allowing the wood to expand and contract with the seasons. Some of the oldest building examples still standing date back to the seventeenth century. The foundations are usually made entirely of chestnut beams due to its high strength and anti-rotting properties, and the base beams simply sit upon stone piles such that nothing is actually secured to the ground (that is, no concrete or planting of beams).