To design a metal building coordination is needed to get the correct code and loads on the building to ensure it is engineered correctly. Coordination is also needed to get the anchor bolt reactions correct so that the foundation is formed with the least amount of concrete for the intended use of the metal building.
All of the above requirements still apply for a metal aircraft hangar, but now one or more huge doors need to operate on and hang from the frames.
When a call comes in to design a hangar we start with the door. We ask the size and style of the door they would like. Whether it is a bi-fold, which folds up into a wedge, or a hydraulic style, which tilts up from the front of the building. Those two options are the most common although a few exotic tilt types exist as well. Other options are a rolling door that would roll on the ground, or a rolling door that would hang from tracks.
The most common type of door that we deal with is the bi-fold, so we’ll use this as our example. The most important thing with a hangar is to calculate the hangar door opening size carefully. You need to estimate the size opening for any future airplanes you might acquire. Take for example if we have a Cessna T210F Turbo. The wingspan is 36’ 6” (11.13M) and the height is about 9’ 8” (2.95M). If you are trying to estimate a door size always calculate more not less. For this aircraft a good hangar door size would be about 46’ by 12’. You can find aircraft sizes Schweiss door sitebifold.com.
Continuing on with our example, if we figure the width at 46’ the math would work out to be 46’ – 36’ 6” = 9’ 6”. If you take the 9’ 6” of free space and divide it equally on both sides it would 4’ 9” on each side from the wing tips to the building structure. That seems fine. If you had to you could easily fit a somewhat larger aircraft in the same hangar, although you would need to take more care clearing the wings on each side.
The height is another matter. If you run the straight math it works out to 12’ – 9’ 8” = 2’ 4” which appears to be enough. However, when you pull your aircraft out nose first, if it has a tricycle gear like the Cessna 210, the slope of the front apron of concrete right in front of your hangar will make all the difference. If the slope is small for drainage the tail will only swing up a little. If the slope is greater the tail will swing up a lot. It is hard to figure the math until it is built, but when designing the hangar we usually recommend plenty of room so that your aircraft will easily clear the tail with a standard slope.
Something else to think about when designing a hangar is the overall height of the building. The FAA has some rules about building close to a runway. They use a sloped line from centerline to figure maximum height. You might want to confirm your metal building works within that height.
For overall height when designing a building I figure the needed door height + door wedge + 1’ of building trim. The door wedge is determined from a table according to width and other factors. If it is a hydraulic style it is only about 9”. For our example with the bi-fold it would be 12’ + 3’ 6” wedge (for that door) and 1’ building trim to equal 19’6“ tall at the sidewalls. The slope of the roof doesn’t matter much although 1/12 is usually the least cost.
Once we have the information for the door size, the code and loads, and the zip code for delivery we are ready to design. For our example we would start with an overall building size of about 52’ (46’ opening + 3’ on each size for frames) by 40’ (our Cessna 210 is 28’ or 8.53M long) by 19’ 6” tall, as explained earlier.
We would then set the frames, girts (wall framing), and purlins (roof framing) like a standard pre-engineered building. We would also add another main frame just behind the left end wall to hold the weight of the door. From that frame we would hang stub columns that would hang down to catch the top of the door, spaced for the hinge points of the door. Once a hangar door is installed and opened, the force (moment force) on the building as it hangs out front is huge. So hangars use back braces. For our back braces we usually use 6” pipe from the second main frame back to the bottom of a couple stub columns. This makes for a very solid design and a good looking building you can be proud of.
It is critical that whomever designs your hangar understands the coordination needed to ensure the door fits together on the building and works correctly once installed. We prefer to work with Schweiss Hangar Doors (bifold.com), although we can design for any door.
To continue with our example, we have preliminarily designed the building from our tables of door sizes, wedge sizes and standard door layouts for costing. Now the builder or owner is ready to purchase the building. They need to do 2 things; commit to the hangar door supplier, and confirm we have loads and codes correct for the design – because they are always changing. Once that happens Schweiss (or your door supplier) would send us the door engineering for the exact door that they are building for that hangar at that location. We take that engineering and detail the building to fit that door exactly. We adjust the hinge points, the weight and the exact overall measurements so that the door will roll up and down on our beams correctly.
When you are getting quotes for hangars check if the supplier or designer has included the face panels, fasteners and trim for the hangar door. When the door supplier sends us the engineering for that specific door it also has trim and panel details. So be sure that when you choose the colors you want on your building, the door panels and door trim are colored as you would like.
In this example I have explained a single stand-alone hangar. There are endless possibilities of building such as, homes, offices, FBO’s or long multi unit T-style hangars where the partition walls define hangar spaces and hangar doors would hang from large beams on the sidewalls.
If you need a hangar, let’s design one together.
We make it easy!