Old House Creaks: Wood Thermal Contraction (3D)

This is a full 3D floor-frame model: floorboards nailed across joists, cooling overnight exactly like a real house does after sunset. Because wood contracts far more across its grain than along it, each board's width shrinks measurably while its length barely changes — and since the boards are nailed down at every joist crossing, that shrinkage has to shear against the nails instead of moving freely. Stress builds silently at each joint until it crosses a slip threshold, then releases in an audible creak. Orbit the frame, tune the cooling rate, moisture content, grain mismatch and joint stiffness, and click any joint to watch its stress build in real time.