Not too long ago, a friend of mine hit upon building a deck as a way to give his large family more space. It eventually worked out great, but as a DIY project it was far more than we were prepared for. When it comes to building decks for a two story home or for a split-level home, it’s common to have the project become more complicated during construction. The majority of two-story homes weren’t built with outdoor decks in mind, and the result is that the house may need significant modifications to make a deck livable.
Without these modifications, a second-level deck becomes a difficult to build and hard to access boondoggle that doesn’t add anything to the home or its value. Happily, making the appropriate modifications actually isn’t too tricky. As long you’re aware of what needs to be done and budget both the money and time, there is nothing stopping you from building a second-story deck and getting a two-for-one in outdoor living spaces. We’ll discuss potential issues you need to be aware of and ways to address them.
Issue #1: Getting onto the Deck
One big issue that building a deck on a two-story home creates is the question of how to get out onto the deck. The majority of second stories aren’t built with doors on the second level even when the main living areas are on that level. It is common to have a second level entry on the front of the house, but since most decks will be built in the back this usually isn’t helpful. Often these houses are on narrow sites, so there isn’t a way to wrap the deck around the side of the house. Even in cases where that’s possible, going through the front door is a clunky way to access a rear deck. The obvious solution is to cut a new door in the rear of the home on the second floor. The problem is that the front and back walls of these homes are usually load-bearing walls. This complicates cutting through them.
Headers Allow You to Create Doors to Access Your Deck
Creating a door in a load-bearing wall requires using a header. These are structural members that bridge gaps in load-bearing spans, and transfer the force to vertical supports on either side. Headers can be made of wood, laminated wood product, or steel. On either side of the header, you’ll need thicker studs to make up for the displaced load. In a wooden wall, these thickened studs are called king studs. Putting a door and header in a load-bearing wall is something that can be done by a reasonably accomplished DIYer. Headers are not, however, something a DIYer should try to design on their own.
Since you need experience in structural engineering to safely design a header, the obvious answer is to hire a structural engineer to do this for you. Structural engineers do charge by the hour, so this will add to the cost of the project. Another option is to contact your local code office and ask them for help. They’ll be familiar with winds, snow loads, and the other loading considerations in your area, and given a proper description of your home, they should be able to tell you what is needed. This advice applies to both levels of your home. If, for instance, you want to add exits to the second story and widen a doorway on the first floor, the code office or an engineer can inform you of everything you need to be aware of, such as being sure not to put one exit directly above the other, for example. Getting this information will also give you a better idea of the constraints you’re working with and your budget.
Issue #2: Stairs Need Supporting Frames
You’ll also need to build a set of stairs to the ground as well as one or more shorter sets of stairs if your deck is on more than one level. You’ll want to keep some design considerations in mind when building these.
There are two kinds of stairways that you can build to access your deck: a single long flight of stairs or several shorter flights of stairs broken up by landings. Shorter flights of stairs are generally safer because they don’t allow one to build up as much momentum during a fall. Shorter stairs can also do things like turn corners, allowing you to climb greater heights while taking up less space. The downside is that framing multiple short flights of stairs requires more material. Each landing is, in effect, a mini-deck that needs to be supported and framed appropriately.
Issue #3: Choosing the Right Posts to Support Decks for a Two Story Home
You’ll also need to consider the final height of the deck. The space between the floor of the second story and the ceiling of the first story is called the plenum, and this is the space where HVAC ducts, wiring, and other modern features are fit into the home. On average this space is 12-14 inches, which means a home with 8-foot ceilings on the first floor will have second-level deck boards around the 9-foot mark. This is well within the structural capabilities of standard deck materials. A 4×4 post should not have any problems supporting a 9-foot tall deck. If your home has 12-foot ceilings on the first floor, then the surface of the deck will be around the 13-foot mark, and at this height it becomes less certain that your typical 4×4 post will be enough. The relevant codes aren’t that helpful, because they only specify that the post used be no less than a 4×4 with no firm rule for when you should switch to a thicker post.
Thicker 6×6 and 8×8 posts are available in most hardware stores. They are also heavier and significantly more expensive than the standard 4×4 post. This leads to the temptation to use these posts only where they are absolutely needed, such as the point where two beams come together. And since the area underneath a second-story deck is meant to be used, these different-sized posts will be on display to anyone underneath the deck, which can look odd.
A different, possibly better, way of dealing with this is to choose light gauge steel framing for the deck’s substructure. It’s a lot lighter than wood, and when working above head-height this speeds up construction and can result in a net savings in labor. It is more expensive than lumber and has to be specially ordered, which does make budgeting and planning more difficult. It also requires some specialized knowledge that might not be intuitive to DIYers, and it’s worth looking up how to build a steel frame deck before deciding on steel for your framing.
Due to the effort involved in building decks for a two-story home, it’s wise to put effort into using high-quality, long-lasting materials like steel framing and moisture-resistant composite decking. The combination of these materials will result in a very durable deck if the highest-quality products are used.
Infinity by Fortress Deck is a good example of a tough composite that works very well with long-lasting steel framing. Unlike other composites, the boards are fully surrounded by a non-slip rubbery coating that resists moisture from all sides. It’s also imprinted with a wood grain pattern on both sides so that it looks good from above and below, which is an excellent feature in a second-story deck that will be seen from underneath. The Fortress line of decking also includes thoughtful features like tread boards that are wide enough for a single board to be used as a stair step. Contact Fortress Deck for information, literature, or samples of their unique decking. Other innovative products from Fortress Building Products include railings and fencing, so check them out if your second-story deck could use railings as well as deck boards.