Before adding a second storyBefore embarking on any home renovation project – especially one as big as adding a second story – there is one thing to think about: the budget. The cost of a second-story addition is often substantial, and if it isn’t considered first, disappointment may come when the contractor gives his estimate. While it’s impossible to give even ballpark figures without having seen the specifics of the project, it is possible to mention some of the things that go into the cost so that those considering a second story can make realistic budget estimates before work begins. Here are some of the most substantial aspects to think about:

Structural Elements

The issue of structural strength is the biggest part of the overall cost of adding a second story. This type of addition requires far more than just removing the existing roof and adding a few more studs for new walls. Instead, the entire structure must be upgraded to withstand the weight of the new story. This can include adding steel beams at key points, improving the strength of the studs on the lower level, and even redoing the foundation.


This aspect is right up there with the basic structural elements when it comes to adding cost. Furnaces and air conditioners are sized according to how many cubic feet of air they’ll have to treat. When a second story is put on, the original amount of space – and the amount of air inside it – is doubled. Expect to have to install a new furnace and a new air conditioner to meet the increased demand.

The house’s electrical system was also set up to handle the expected demand of just one story, so it’ll have to be upgraded instead of simply being expanded. 200-amp breaker boxes are the norm for a two-story house. Expansion will be needed, too, so be ready for the cost of all of the new wiring.

If the house has a fireplace, the chimney will no longer be long enough to reach the outside after a second story is put on. Fixing this requires extending the chimney up to the new, higher, roof making the chimney longer and more expensive.

Alternatively, wood-burning fireplaces can be replaced with gas units. A gas fireplace produces much less exhaust and can be vented through a wall chimney instead of out of the roof.

Water heaters are often sized according to the square footage of a home, so the house may need a bigger one when a second story is added. While some recommend this as a matter of course, the reality is that this will depend on expected changes in water usage. If more people will be moving into the home or young children will be growing up there, get a bigger one.

Visible Aspects

These are the parts most people think of when they consider adding a second story, and therefore, the parts most have already budgeted for. They include the walls, windows, flooring, and other obvious facets of construction. The cost of these elements vary widely according to style, construction materials, warranties, and similar factors. After considering all of the things that go behind the walls and under the floor, it can be easy to forget about these more-obvious factors! Alas, they still aren’t free, so put them into the rough estimate.

With proper estimation, there’ll be no major surprises when it comes to the cost of adding a second story to a house. Even so, it’s typical for the final estimate to be a bit different from what a homeowner expects. Be sure to talk to an architect before beginning work to get an estimate that reflects current labor and material prices, and, of course, to get a building plan that will result in a beautiful and stable structure.

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