Our all-wood spiral stair design and construction is unique to Salter Spiral Stair. With our in-house wood shop, we have designed spiral stairs that have no metal sleeve inside the column. We manufacture our 5″ solid wood round center column. The design of the tread connection to this column ensures that strength will never be an issue for the life of the spiral staircase. In addition, the main baluster on each tread connects the upper and lower tread creating another point of strength on the step. Our balusters are 1¾ of an inch thick versus typical wooden balusters which are only 1¼ thick. Lastly all of our treads have a tread end on the outside of the step which creates support and prevents the wood moving or cupping.