We asked one of our lead engineers, Nathan Pfeifer, to give us the answer. Nathan talks through design considerations, limitations, and of course the possibilities of exterior wood ceiling applications.
Q: Does 9Wood do exterior wood applications?
“A question we get quite often, is whether or not we can do exterior applications with our wood ceilings. And the answer to that is yes.
Q: How do we define exterior wood application?
How I would define an exterior wood application? One that is outside the building and does not have a controlled climate, but one that is also protected from the elements? So, for instance, underneath a soffit, breezeway, or where the ceiling is protected by the structure. I would classify an exterior soffit different than an exterior cladding, as an exterior soffit is going to be more protected from the elements, so we don’t have to worry about direct contact, for instance, rain. 9Wood does not do exterior cladding.
Q: What is the best type of wood to use in an exterior application?
Wood expands and contracts due to changes in relative humidity. In an exterior environment you can’t control that, so we have to choose materials that do better in those types of applications. Vertical grain material is just going to be more dimensionally stable than, say, horizontal. Based on the type of finish system, we use the species that we find works best with an exterior application, such as douglas fir and hemlock, which have very good finish adhesion characteristics as well as dimensional stability.
Q: Are there any limitations to exterior applications?
Another limitation is going to be core type, assuming we go to a ply core vs. a particle board, or MDF. One of the other limitations is going to be edge banding, so anytime we are going to do something like a tile, that requires an edge treatment. We would not be able to do an edge banding application. Our exterior finishes differ from our interior finishes, in that they are more robust. A hard kind of shell coating, which is a protective coating, vs. a penetrant, like in decking, that is more like an oil.
Q: Can you apply a stain to exterior wood ceilings?
For exteriors, we can provide a stain. In fact, pretty much all of our stains would be available for exterior application. Just like any other exterior application, whether it’s a deck or a trellis, some refinishing will be required at some point. It’s hard to say exactly when that will be, as every project is different. Typically, if we’re doing a protected area, a fire rating can be applied, but if anything is going to have exposure to the elements, let’s say it’s coming down the wall a little bit, those particular applications would not allow us to use fire rating, simply due to finish adhesion.
Q: What are some design considerations for exterior wood ceiling applications?
Some of the design considerations, when choosing a product for an exterior application, are the exposure. How exposed to the elements is the product going to be, material sizing, reveals, those things that will help mitigate the look of wood movement. Some other aspects that need to be considered are hardware. You’ll want to use something that is a non-corrosive material, and can stand a little bit of wind uplift in those types of things. As it relates to interior suspension, we almost always use a T-Bar suspension system. In an exterior we typically will propose a light gauge metal framing, that’s mainly to deal with wind uplift. One of the other design challenges in an exterior is wood movement. Because the environment is uncontrolled, you’re going to tend to see more wood movement then you would see in an interior. Therefore, you’ll want to have designs that accommodate wood movement, things that would help mitigate some of the impact to reveals, member alignments and those types of things.
Another design challenge that most people don’t really think about until it becomes a problem is bugs and birds. They can tend to nest up in the ceiling area, and if you have large reveals, it can create real challenges down the road.
A wood ceiling can last a very long time in an exterior application, assuming that the material is maintained from a finish standpoint. In theory it could last the whole life of the building.”