I grew up having to slide open hangar doors to get my Dad’s 182 Cessna in and out. I didn’t like sliding hangar doors as a design solution then, and I like them even less as an adult.
Let’s start the discussion with simple….just “plain old” sliding hangar doors, mounted on the outside of the hangar.
For starters – wood framed sliding doors are automatically excluded. The vertical members do not have the strength to carry wind loads, and (unless the doors are very, very small) wood horizontals cannot carry the loads either. This means aluminum or steel framed doors are the only viable solutions.
Least prone to maintenance issues, as well as most secure, will be doors mounted on a single track. As a minimum width door opening is probably 36, if not 40 feet in width, this rules out the practicality of a one piece door. Although still fairly large in width, split (also known as bi-parting) sliding doors might be a consideration.
Bi-parting sliding hangar doors are actually two independent doors, with an astragal to connect the two together when closed. Properly designed, they should include a method of positive anchorage at the center, to the ground. An interior latch system should firmly lock the two sections in place at the middle, when closed.
Most, if not all of us have seen older hangars with sliding doors which slide past the corners of the pole buildings and are mounted to headers supported by wood columns placed at a distance away from the building corners. I would strongly discourage anyone from going this route. Besides the remote columns becoming magnets for planes and vehicles, they take up valuable space which might not be available to begin with. And, what happens when a door or doors are left open, and the wind picks up? Not only is the wind speed picking up a concern, but there is a good chance the doors are going to be picked up, and deposited somewhere potentially uncomfortable. Flying sliding doors present an extreme hazard to living creatures!
In an ideal world the sliding hangar doors would fit across the building face, with no door projecting past a corner. This poses some challenges, as a 36 foot width door, would require a 72 foot wall.
Taking things up a notch would be the use of double sliding door tracks. For a 36’ width opening, imagine four door panels, each nine feet wide. The center two panels mount in the outer track, with one panel to each side of these, on the inner track. On the plus side, the doors can be opened onto only nine feet of building wall on each side of the opening (so for a 36 foot wide door, 54 feet of building wall would be required). The down sides are – lots of moving pieces and the doors have to slide past each other (so do not seal well).
I’ve only done triple tracks one time, and hope to never do them again. Imagine, if you will, the complexities of double tracks….triple is going to pose an immeasurable increase in challenges, and decrease in user satisfaction. Somehow the challenge level of sliding doors appears to equal the square of the number of doors. A split sliding door (2 pieces) would be rated at 4. Six doors on triple tracks would be 36!
A big design consideration, with sliding doors, is the weight they impose upon the roof system. In most cases, sliding doors will be hung from a track supported by the end truss, rather than having weight transferred to the ground. The roof truss manufacturer can redesign the end truss to adequately support the extra moving weight from the doors. Often this results in a two member end truss. What is often neglected is to adequately transfer the lateral loads imparted by wind against the door sections and transferred to the end truss bottom chord. Registered Design Professionals will typically provide extra T or X braces to transfer these loads from the truss, to the roof diaphragm.
In a future article, I will discuss what most would look upon as being better solutions.