Housing treads and risers in open string

• Open string is a string which cut to the outline of the treads and risers to show the profile of the steps . 
• A flight with an open string is more expensive than one with closed string . 
• More labout is involved . 
• Fixing of treads and risers to open outer string cannot be supported by housings in the string . 
• Secured to brackets screwed to both treads and risers and string . 
• Planted nosing are fitted because it is difficult to cut a neat nosing on the end of treads to overhang the open string . 
• Planted nosings are secured to the ends of treads by slot screwing to avoid the heads of screw exposed . 
• (dovetail balusters housed in treads )
• (cut outer strigng )