The Appeal
I am seeing more and more requests for hangar home combinations where the living area is built above the hangar. Around the Internet there are a few pictures of projects, some which have not yet been built, which show nice and neat depictions of this type of an arrangement. Its appeal, on certain levels, is easy to understand. Such an arrangement can be tidy and well contained and not be as sprawling as other types of projects with hangars on the same level as living area, or even separate.
There can be some advantages to having the living area over the hangar.
This type of an arrangement can lend to very nice opportunities to view the runway from the comfort of one’s home. With the living room, or family room or other common areas of living space set over the hangar these can be designed to face the runway giving the occupants a wonderful theater from which to watch their fellow pilots land airplanes. This can be quite enjoyable as any pilot knows who has sat in a chair applauding, and perhaps judging, landings of his compatriots.
This arrangement can be advantageous for narrow lots where separate hangar and living structures might force the living area to be built away from the runway with the hangar between. While this may be something desired in some cases, I find that many folks, if on the runway, request some sort of runway view. If the lot is small this can be difficult to achieve by any other means.
Going “up” with a design has some inherent efficiencies in that the same roof covers both living area and hangar and the same slab, or lower floor, functions for both areas. There is an ongoing debate in the industry as to which is cheaper to build, a one or a two story home. In my own evaluation I have found two to be comparable when all elements are taken into consideration. But nonetheless there is an inherent efficiency to having the home rest over the hangar area.
The Challenges and Solutions
However there are several disadvantages and challenges for this type of arrangement and this could be the reason why there are not more of these types of structures to be found.
The key problem with having the hangar under the living area is that, given the typical sizes of hangars, usually at least 2000 ft.² with a typical width of 50 feet, it is difficult to span that distance with any structural element that can withstand the deflection forces of the live loads. Though structural elements can be designed to hold the weight the problem falls in the area of deflection which can manifest in what is called, in the industry, “bounce”. Bounce is basically the vibration which can be detected by human occupants as a result of shifts in position of various users of the space. One can be sitting in the living room and have a group of children running across the living room and actually feel the vibration of their movement in the floor and furniture. This can be unsettling. Though not an actual structural problem it is more a problem of perception. It is, by its nature, somewhat subjective but studies have been made on the subject and bounce is a real potential problem.
The only solution to the bouncing problem is to have the structural member designed with enough stiffness to resist deflection. Stiffness is largely achieved by a structural element's depth. If one is using a beam of even 2 feet of depth across the 50 foot span this would generally not be sufficient to handle the “bounce” to the extent most people would find desirable.
Of course, these factors can be controlled by limiting the size of the hangar but generally most folks want to have at least 2000 ft.² of hangar space and a typical size for this is 50’ x 40’. The 50 foot side is usually the side for the hangar door. Running the beam from front to back would have its own inherent problems of causing a substantial point load in the middle of the hangar door header system.
So limiting the size of the hangar can certainly mitigate some of the bouncing problem. It is a matter of whether or not the owner is willing to live with a smaller hangar.
I have had owners quite satisfied with smaller hangars.
Another solution is to add a post to the beam. This makes all the differences by, effectively, cutting the beam length in half (if placed in the center). One of my clients, in North Carolina,, is parking a relatively small home-built airplane in his hangar and is able to tolerate a post set in the middle of the long beam. He is able to easily park his aircraft in the space despite the post.
Another strategy is to use a “T” hangar where the tail, or even the nose, rests in a more narrow portion of the hangar. This design segregates the rear left and right corners of the hangar into either living areas or some type of shop or storage space. It opens up the opportunity to create load-bearing members in strategic locations to reduce the length of the main supporting element for the home upstairs.
Another, less common, strategy is to create a “wall truss”. This can be a major wall contained within the living area upstairs which is designed as a deep truss to support secondary floor and roof structures. Passageways through the truss can be challenging and that is part of the job of the designing engineer to solve.
Three Other Challenges.
The living area over hangar concept can be “boxy”. There are ways around this but the basic massing of this type of structure is a challenge that needs to be handled in most cases.
Secondly, this type of arrangement puts most of the living area on the second level requiring either stairs or an elevator for egress. If the owners are entering the senior status of life this can be a factor and an elevator is can be the best solution.
And, finally, if the hangar exceeds 2000 sqft in size, substantial fire separation requirements can kick in. These require special structures in the ceiling of the hangar to separate the hangar and living spaces. This is quite technical, and can usually be solved.
A Trend that begs for Solutions
It appears there may be a trend pointing to an increased popularity of the home over hangar arrangement. I think it behooves designers and engineers to begin solving this set of interesting challenges. Homes over hangars can be quite charming and even include decking placed in front of the home, over the hangar, providing a great area for relaxing and watching the aviation experience.
Engineering
As a hangar home designer, I occasionally get requests for a hangar home to be built on top of the hangar. Interestingly enough, I've not seen many of these actually built. In my own neighborhood of over 50 hangar homes we do not have a single instance of a hangar with a home on top. But throughout the Internet there are many pictures of such projects. I don't know the actual percentage of hangar homes that are built which use this format but I suspect that is a relatively low number. This may be changing. Here is one example of a home that I see popping up on the internet. As I understand it, it has not yet been built. But it is an appealing look. You might notice that the hangar does not appear to be very wide - and this is a duplex.
Placing a home over the hangar can be an excellent idea if faced with a tight (ie. small) building site. If properly designed, these types of structures can be efficiently build utilizing a relatively small ground floor area for relatively large usage space.
But on the negative side, these types of projects can look boxy. There are remedies (see below) but the nature of these structures tend to lend to a heavy "over/under" look. They also tend to force the hangars to be relatively small due to structural challenges which I will describe below. They can also quickly push the height restrictions since hangars need to be relatively tall and with the addition of a home on top can push some zoning limits. Another disadvantage is that the cars and the living area are on separate levels forcing one to use either stairs or an elevator to get up to the living space. Even two-story homes associated with hangars have a lower living level which will contain the kitchen and common living areas which is quite convenient for bringing in the groceries, accepting guests etc. It can be awkward having guests climb stairs to find the front door. If one is looking for a two-story home it is essentially impossible to do over a hangar because it will bring a height of much higher than many local zoning requirements will allow. Plus it will look very much out of balance.
The main structural challenge with a home built over hangar is that since we do not want any types of structural posts inside the hangar the hangar must be spanned by a beam of sufficient size to handle the loads. This tends to restrict the size of the hangars, either in width or depth. A reduced depth can allow us to bear the structure of the upper home on both the front and back walls and not create problematic floor joist spans. A reduced width will allow direct use of shorter structural members, again, reducing the span problem.
While beans can be easily designed to carry the required loads, the problem is, what we call in engineering, "deflection". Deflection is the tendency of a beam to drupe or bend downward as a result of the weight that it is bearing. This, in itself, is not a problem and can be controlled but it can lend to a phenomenon called "bounce". If the beam is not "stiff" enough it can cause the floor above to vibrate and bounce as a result of any type of standard human traffic. I've been in structures where this had not been properly accommodated, and could feel the floor moving and bouncing with just a few children running from one end of the structure to the other. The beams were "strong" enough to be safe but not "stiff" enough to prevent the bounce.
"Stiffness" is a function of many factors but the beam depth is a big one. The key solution to reduce bounce is to design the beam to maximize its depth. Its depth has to be significant compared to its length. The longer the beam, the deeper it must be.
There are ways to do this. A beam can directly be chosen due to its substantial depth but this can be an architectural challenge in that it might protrude quite a bit into valuable spaces. Another way is to "skin" a strategic wall in the home above and letting it act as a deep beam unto itself. This can be cleverly designed and can certainly handle the situation. In these types of beams, depth is more important than weight.
If one is looking to have as living quarters above the hangar, the easiest solution is to build a smaller hangar, either in depth or width. If an owner is happy with the hangar size such as this, it can be an excellent way to proceed.
To handle the boxy look one can add facade features as well as design outcroppings to add interest.
In my experience, the majority of hangar home owners like to have their homes look like a typical residence and to de-emphasize the overwhelming effects of the hangar. With good architectural design this is relatively easy to achieve. It is easiest to achieve when the home and hangar are spread over a larger site which allows the architectural elements of the hangar and the home to gracefully blend. Personally, this is my favorite way to attack such a project.
If you are looking to build a hangar home, certainly do not hesitate to consider every option available. An experienced hangar home designer can surely help. Whether you choose a side-by-side hangar home structure, or choose to place the home over the hangar, an excellent solution can always be found.
See Additional Articles on this subject. Home over Hangar Arrangements.
I was asked to write a guest article for another website about fire separation requirements in hangar home projects.
Check it out.
Ken Risley on Fire Separation in Hangar Homes
