Second-floor additions can be a wonderful option for those people with a house and a neighborhood that they love, but with no room to add out to accommodate growing space needs. Even if you have the space for a first-floor addition, adding up may still make sense if you're looking to maximize views or perhaps provide some additional privacy for a home office or and additional rental space. If adding up is something you're considering, there are a number of issues to explore before the first nail is ever driven. As with all construction projects of this magnitude, you really need to do your homework early on.

Keeping it Legal
Height restrictions are the first thing to check. Many towns have city or county ordinances that restrict residences to specific heights, so you'll want to check with your local planning department to see if height restrictions are in place. Building heights are usually measured from the average ground level of the property to the height of the tallest ridge, but this not always the case. Be sure and ask exactly how "height" is defined and calculated before you make any incorrect assumptions. Certain areas may also be height-restricted due to their scenic location and the impact a tall addition may have on surrounding views. Many communities also now have solar ordinances in place that can affect a second- or third-story addition if it will block or substantially alter the amount of sunlight falling on a neighbor's property. The planning department can help you out with all of these issues as well. Your final question while at the planning department is to verify if the intended use of the addition will be allowed. If you have a single-family dwelling and the addition will simply be an extension of that use, there shouldn't be a problem. But if the addition will be a separate rental space, that may not be allowed in certain zones. There may also be some restrictions if the addition will be used for commercial or home occupation purposes and you will have clients  or customers visiting  you  there. In addition  to  the city or county, if you live in a subdivision there are often specific rules concerning  what can and

can't be done with a piece of property. Called covenants, conditions and restrictions (CC&Rs), they can cover a wide variety of things that you may not be aware of. Height limitations may be more restrictive in your specific neighborhood then elsewhere in your city, or second-floor additions may be restricted to a certain percentage of the overall square footage of the original house.

Some Building Considerations
Second-floor room additions may seem fairly straightforward at first glance, but in actuality they can often be far more tricky than adding out. Ground-floor additions can be almost completely constructed before the walls between the old rooms and the new ones are knocked out, which greatly simplifies weather protection. With an upper-floor addition, however, the roof needs to be removed at some point fairly early in the construction process, and the structure left open to the weather during the first framing phases. For that reason, speed, good job planning and coordination, temporary weather protection, and a close eye on the Weather Channel are all critical considerations.
Another very important consideration is the size of your home's existing foundation. One-story and two-story houses utilize different sizes of foundations and footings because of the greater amount of load that the foundation on a two-story house must be able to bear. If the existing foundation is undersized for a second story, it might be necessary to reinforce it.
Yet another important framing consideration is the size of the existing ceiling joists. In a one-story house, the ceiling joists need only be large enough to support the finish ceiling material that is attached to them, and they're usually too small to handle the additional load imposed on them if they must act as floor joists for the second floor. Adding new floor joists of the proper size next to the old ceiling joists usually solves this problem, but you'll want to take a close look at the existing framing to make sure this is possible.
All these municipal and framing issues probably sound like insurmountable tasks, but with a little help from an architect, structural engineer or an experienced contractor, that new living space can certainly become a reality.