In the most scenarios, a single story addition to your home should cost less and be easier to build than adding a second story.
However, a second story addition will save yard area for outdoor activities. And if your single story home already maximizes your lot, your only option for more space would be to add up (or down, but that discussion is for another day).
The first thing to consider is the zoning for your area. It is important to know what your property’s zoning designation is to find out whether you are allowed to build an addition outside of the existing footprint of your house. The setbacks and zoning vary from one town to another, so check with your local planning department for the specific regulations for your property
Some cities in the Tri State Area require a special review if you plan to do a second story addition. This is another important item to ask your local Planning Department. For example, in the City of Clifton, a second story addition does not require an overly involved planning review (if kept over the existing footprint). In not too distant Wyckoff, NJ, expect to have a much more substantial review process due to set architectural guidelines. In Upper Saddle River, NJ, the Historic Preservation Commission may have certain requirements which will need to be addressed in your addition.
Another important issue is that you must not remove windows from an original room without replacing those windows with new ones. We have seen many additions that have left kitchens in the dark, or bedrooms without any means of escape (if there’s a fire). Always keep in mind that you need natural light and ventilation for all rooms (bathrooms and utility rooms are exempt from needing natural light).
Cost wise, a second story addition will often cost more than a single story addition of the same square footage. That’s because most single story homes do not have an adequate foundation to carry the burden of another story. So, it is likely that the home’s foundation will have to have extra support added to it. This could also mean opening some of the existing floors and walls to add the extra support.
Connectors called “holdowns” and shear walls may also have to be added to strengthen the whole building to meet with current building codes. You may also have to hire an architect or engineer to specify the proper connectors and provide the township with calculations. The structural modifications will add to the cost of the project, but in the long run you will have a safer home designed to withstand stormy weather.
Lastly, always get a building permit for any addition that you do for your home. This protects you from poor construction that may put your family’s safety in jeopardy. It will also allow you the best possible return on your investment when you later decide to sell your home.