Jim writes: At what width do you go from 2 stringers to 3 stringers in a wooden staircase?
In my stair case articles, I neglected to write about when it is necessary to add a third stringer to support the stair case. I would go to a third stringer when the stair case width exceeds twenty four inches. I like a solid feeling staircase. Walking up and down the staircase I shouldn’t feel the staircase bounce or flex. I have seen track home builders locally who have built 36″ wide stair cases using only two stringers and these are stairs that run straight from the first floor to the second floor. With just one set of jacks supporting the stringers roughly in the middle of the run, if that. Boy, did those stairs have some flex in them!
Staircases that have a landing you can go with a wider width using only two stringers, if you want to. If the landing is half way between the first and second floors you should still add a third stringer if the the stair case width exceeds twenty four inches. Now, if the landing is close to the first floor, then the small section of staircase you could push it to thirty or thirty six inches before adding the third stringer. These small sections of the stair case are short enough to allow for a wider span and still being fairly stiff.
A stiff and firm staircase is important for a couple of reasons:
- It feels good and makes the person walking on the stair case to feel secure and confident that they are not going to fall down.
- A flexing staircase tends to damage its finish especially if the treads are hardwood and finished with stain and varnish. The finish will crack and will look ugly.
A good practice is to test your stair case when it is roughed in. Walk up and down it. Have some friends and or family members walk up and down it all at the same time. Plenty of load on the stair case will quickly let you know if you need to reinforce the stringers to make it stiffer.
