Closed Stringer Stairs Closed stringer stairs, also known as housed stringer stairs, are a type of staircase where the treads and risers are fixed between two solid stringers that are set into the wall or the supporting structure. In closed stringer stairs, the stringers are enclosed or “housed” by the treads and risers, creating a solid and sturdy support for the staircase. For More Information visit here: https://elitestaircases.co.uk/close-stringer-stairs/