Building a Second Floor Addition versus a Room Addition

Deciding on Whether to Build Up or Out on a Home Addition Project

By Mark J. Donovan




If you have a growing family and are in need of more finished living space, you have two choices; increase the size of your existing home or move to a larger one.

Selling your existing home and buying a larger one is typically a very expensive endeavor.

Not only will the larger home cost more, but then there are all the costs associated with selling your own home and paying all of the related state property transfer taxes.

Then there are the moving costs and utility cancellation and new hook up fees.

As a result of all of these costs, many homeowners choose to expand their existing home by either adding a room addition onto their home or building a second floor addition.

Deciding on what makes the most sense for your particular needs, in regards to building a second floor addition or building an attached room addition, really depends upon what type of additional living space you’re looking for and what your home and lot can physically support.

For example, if you have a small lot, then you may not have the space to add on a room addition to the side or back of your house. As a result, your only solution may be to build a second floor addition onto your home.

In general, if you have the land, it is more cost effective to build a room addition onto the side of your home than to build a second story addition on top of it. With any home addition, it is a major construction project. As a matter of fact, it really is like building a small new home.

Building a second floor addition only adds to the complexity, risks, inconveniences and cost. For example, the existing home needs to have its roof removed and effectively a new home built on top of the original one. Moreover, a second floor addition pretty much guarantees the family has to move out of the home for a period of it.

In addition, building a second floor addition is fraught with additional risks and concerns associated with weather and ensuring the main level of the home is not damaged during the second floor construction. For example, ensuring the drywall ceiling on the first floor does not suffer extensive damage and/or cracks is extremely difficult to do when building a second floor addition above it.



Key Factors to Consider when Building a Second Floor Addition

Make sure to check with your local building inspector before thinking too long on building a second floor addition. There may be building code, zoning, or covenant concerns.

In addition, the building inspector will be able to tell you if your existing home will be able to support a second floor. Or more likely, what additionally you’ll need to do to the first floor to shore up its ability to support the weight of a second floor addition.

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There is also the possibility that the home’s foundation walls and concrete footings may not be adequate to support the weigh of a second floor addition. For example, if you have a small ranch style home built on a foundation wall, the concrete footings that support the foundation walls may not be sized large enough to support the weight of a second floor. If this was the case, and you went ahead and built a second story addition on top of the ranch, there is the possibility that the house could settle significantly and make the home become structurally unsound.

As a result, if you have a similar type home and are contemplating building a second story addition, you may need to work with the building inspector and a foundation contractor. They can help determine how to beef up your home’s foundation walls and concrete footings in order to be able to legally build the second story addition.

Building a second story addition also means having to remove the home’s existing roof. This means your home, and its contents, will be at risk of being damaged by water and weather related issues. Great care will need to be given to prevent your home’s lower level from being damaged by the weather elements.

It’s also important to keep in mind that removing a roof in a careful way, as to not damage the lower level rooms of the house, is an expensive endeavor and thus will add quite a bit of expense to the cost of the construction project.

Building a second floor addition vs a room addition

Building a second story addition also pretty much guarantees having to move the family out of the home for a period of time. This means that you’ll have to find temporary housing which adds cost to the project.

Key Factors to Consider when Building a Bump-Out Room Addition

One of the chief benefits of building a room addition onto the side or back of your home is that the work is isolated from the main part of the home for much of the construction. Only when the room addition is nearly done, does a doorway or opening have to be punched into the main home. As a result, building a room addition is much less disruptive to the family.

Although building a room addition requires its own concrete footings and foundation walls, it is a clean effort. There is no disruption to the existing home.

The excavation is done, the concrete forms are erected, and the concrete is poured. When complete, the framing can be constructed on top of the new foundation walls.


Lastly, because there is little demolition required in building an attached room addition, there are minimal additional costs to tie it in to the existing home. Typically only a little house siding and roofing work has to be done to tie the new attached room addition into the existing home.

To conclude, building a second story addition has its benefits. It doesn’t require expanding the footprint of the home, and it can effectively double the finished living space of the existing home. However, building a second story addition, compared to building an attached room addition, is a much more expensive, riskier, and disruptive enterprise.

So, before choosing to build a second floor addition, make sure you know what you are getting yourself into, and if at all possible, consider going the route of the attached room addition.


For more help on building a second floor addition or a room addition, see HomeAdditionPlus.com’s Home Addition Bid Sheets. Our Home Addition Bid Sheets provide you with the knowledge and information on how to plan a home building project, and what to look for when hiring contractors. They also include detailed cost breakdown tables and spreadsheets for estimating your own new home construction building costs.

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