Can I Slap a Second Level on Top of a Single-Level House?

If you live in a single-level house, or are considering buying one, you might have wondered about building up. Before you start imagining a roomy new second floor, here are three considerations:

First, the foundation. In some cases, you can "slap a second story on top," but only if the foundation of the first floor can take the weight. Foundations come in many varieties, from slabs to basements and sandstone to cinderblock. You need a construction engineer to determine if adding more weight is feasible. You might also wonder if the foundation can be reinforced to take a second level. The engineer will let you know.

Second, the construction. Your contractor will need to integrate the new addition with the older parts of the house. That can be easier or harder. For instance, if you're adding a second level to your garage, you might be able to have a crane simply lift your current roof off, then pop it onto the new level when ready. Your architect will clarify the construction plan with you.

Third, the contractor & cost. You'd need to find a contractor who's creative and willing to take the time to do this kind of project. Figure on doubling or tripling the cost-per-square-footage of typical additions.

Even with these warnings, it still might make sense to build up. If you’re trying to stay in your current location, then a second level might be more cost-effective than buying a larger home.