I was walking down the street the other day, and I noticed that all of the entrance doors on the building I was passing had A LOT of intermediate pivots. I didn’t have much time to investigate, but I took a picture in case I decided to do a blog post about it someday. Well, someday is today because I just got an email from one of our specwriters about how to determine the required quantity of intermediate pivots.
Intermediate pivots are typically used with a set of top and bottom pivots, or a top pivot and a floor closer. The bottom pivot carries much of the door weight, and the primary purpose of the intermediate pivots is door/frame alignment (although most manufacturers’ data states that greater door weight can be accommodated when intermediate pivots are used).
The rule of thumb is that doors over 60″ tall require one intermediate pivot, and an additional intermediate pivot for each additional 30″ of height. So if I’m interpreting that correctly, a door up to 89″ tall would have 1 intermediate pivot (in addition to the top and bottom pivot set), a door up to 119″ tall would have 2 intermediate pivots, and a door up to 149″ tall would have 3 intermediate pivots.
The formula for pivots is different from the way you determine hinge quantity. With hinges, you use 2 for the first 60″ of door height and then an additional hinge for each 30″ of door height. So a 7′ door would have 3 hinges, or one intermediate pivot + the top and bottom pivot set.
Unless the doors at right are REALLY tall, I think they have more than enough intermediate pivots.