Hardi plank siding is made of cement fiber board. This particular material bears a strong resemblance to wood. Hardi board has all of the grains and textures that you would enjoy with wood siding. Unlike wood, cement fiber board is waterproof and can withstand all temperatures. It is also resistant to rot and termite damage. Hardi plank siding is manufactured to maintain the paint a lot longer without peeling and chipping, especially in extreme temperatures.