Home Additions: Building Out vs. Building Up

Choosing to remodel your home is a significant undertaking, one that comes with many considerations. This is especially true if you are looking to expand the size of your living space. The first thing you need to decide is if you are planning on “building out” by increasing the footprint of your ground floor, or “building up” by adding a second story. Of course, the right answer depends on your needs and preferences, plus physical and budgetary constraints. In this article we will focus on the pros and cons of building outward vs. building upward.

Advantages of Building Outward
Building outward inherently carries with it several advantages which, taken together, might steer you in this direction. These considerations include:
• fewer structural issues
• usually less expensive
• fewer disruptions to daily life
• inherently accessible
• shorter lines of travel

Fewer Structural Issues
Ground floor additions are more often than not the simplest from a structural perspective. They can often be built to Code without having to structurally retrofit much if any of the existing home. This can result in lower overall costs compared against second-story additions often involving structural retrofitting down to the foundation plus disturbance of interior walls. Taken altogether, these factors tend to result in a less intensive project of shorter duration.

Less Expensive
A ground-level addition on a flat property is quite often the least expensive square footage you can add to your home. But throw in a steep slope, a complex relationship to the existing house, and/or challenging access to the construction area, and the costs can easily rival the cost of a second-story addition. Talk with your architect about which parts of your plan are cost drivers, and make choices necessary to limit their impact.

Less Disruptive to Daily Life
When you choose to build out, the work to be done happens on the ground floor. Since construction is happening to the side of the home rather than overhead, it’s more likely you can remain living in your house during the course of construction. Of the two options, building out usually involves the least disruption to the existing home, and thus to life’s daily activities, during the duration of the remodel.

Easy Accessibility
Building out consigns all activities to a single floor. This can be helpful if you are living with a family member for whom stairs may be difficult. Keeping things on the ground floor make accessibility simpler and keeps members of the household in closer proximity. More people are opting for a design approach called “Universal Design”, the design of buildings with the goal of having them as accessible as possible to people of any age, size, ability or disability.

Shorter Paths of Travel
A single story home inherently has shorter lines of travel than its two story cousin, meaning that living in a one story house will tend to be a tad simpler and more efficient than living in a multistory home. For example, checking on your children by calling into the next room instead of putting your work aside to head upstairs saves time and energy. Similarly, when it comes to housekeeping, building outward eliminates the chore of lugging a vacuum up and down stairs, or leaving a hot stove to do a check-in on other tasks. Building outward can therefor make things a bit easier when it comes to being “everywhere at once” for a working homeowner or person with a family.

Disadvantages of Building Out
While expanding your home’s footprint horizontally could very well be the right approach for you, make certain you are cognizant of the downsides that attend building outward. These include:
• cost of excavation and new foundation
• lost yard area
• potential zoning limitations

Costs Associated with Excavation and Foundation Work
If you decide to build out, you’ll need to anticipate the cost of excavating plus new foundation work. Foundation prep will require leveling and compacting the soil in preparation for the home’s outward expansion. It may also entail tree removal and will certainly require erosion control measures. Excavation and foundation costs will be dependent upon the extent of new footprint and thus the area of impact. Depending on the home’s proximity to property lines you may find it necessary to commission a property survey, and if the disturbance of the ground is extensive or involves drainage challenges, the services of a civil engineer.

Yard Loss
Inevitably, you will lose yard space by building outward. Once you build the ground-level house addition, this is space that can never be recovered. In extreme cases, this can put a serious crimp on your lifestyle if outdoor spaces are an essential part of what it means to live well. Similarly, unless carefully considered, expanding outward may preclude the possibility of a future detached garage, ADU, or swimming pool. Finally, you have young children about it may be important for them to be able to play outdoors. In this case the solution may be to hold off on the addition until they have matured or no longer care about outside play.

Zone District Limitations
Most regulatory agencies enforce strict setback requirements that limit your ability to build any closer than a certain minimum distance from the property line. Depending on how much space you’re hoping to add and how far your home already is from the perimeter of your lot, zone district regulations have the potential to be the deciding factor in your decision to build upward vs. outward.

The Advantages of Building Up
Adding a second story to your existing home could be the more advantageous path for you. Building upward inherently carries with it several advantages, including:
• improved access to views
• improved cross ventilation
• no lost yard area
• more street presence
• zoning activities vertically for optimum functionality

Access to Views
A second floor addition will always result in varying degrees of improvement to the views available from the home. Even a dense urban environment will afford enhanced views down-block or distant glimpses of faraway landscapes over rooftops. And if the view to be gained is that of a distant landmark or, even better, a glimpse of a lake or the ocean, any realtor worth their salt will tell you that’s worth gold when it comes to resale value. And even if resale is not a consideration, for many the resulting lifestyle improvement itself is priceless.

Better Cross Ventilation
A positive feature of a two story home is that upper level windows can be kept open without security concerns, day or night. This can be an excellent feature on hot summer days, allowing fresh air to circulate throughout your home as you rest or take in the soothing sounds of nature.

No Lost Yard
Building upwards entirely avoids loss of valuable yard space. On smaller lots this fact alone can be the key to deciding whether to build up vs. out. And even on not-so-small lots, if some portion of the yard is earmarked for a detached garage, ADU, or future swimming pool, this can be the deciding factor driving the decision to build upwards.

Improved “Presence”
Adding a second floor results in a taller building, thus lending it a greater prominence relative to that of a one-story home. This in turn results in the home having an enhanced presence on the block. Combined with a winning roofline, this approach always results in enhanced curb appeal for the home, and hence greater value, if resale is a consideration.

Zoning for Optimum Functionality
Adding a second story allows an organization unique to two-story homes. On the main floor, public functions such as family entertainment or periodic family gatherings can take place in zones dedicated to these functions, including the kitchen, dining room, and living room. Meanwhile, bedrooms are zoned upstairs, keeping them away from noisy activities and lending them an additional measure of privacy.

Disadvantages of Building Up
Just as with building out, building upward also has its share of challenges which must be accepted in order for this approach to work successfully. Some of these factors include:
• potential need for temporary housing
• the cost of retrofitting the foundation
• potential zoning restrictions
• floor area dedicated to new stairway

Potential Need to Temporarily Relocate
Building up instead of out requires that some portion of your existing roof will need to be demolished. The amount of roof area impacted is that square footage displaced by the proposed upper floor. Once the roof is off, given the inability to maintain thermal comfort in the affected rooms plus the construction crew’s heavy foot traffic, your choices will be: a). sequester your family in those portions of the home not impacted by the alterations or, b). stay offsite – in a hotel or perhaps with extended family – while the remodel progresses.

Expense of Retrofitting Your Foundation
Depending its size and depth combined with the loading configuration which will be demanded of it, your existing foundation may need to be retrofitted. Retrofitting your existing foundation will lend it the competancy to support the additional weight imposed by the new addition. Care must be taken to factor this expense, plus that of potential impacts to interior walls and footings, into your construction budget.

Potential Zoning Restrictions
Although rarely a deal-breaker, most local jurisdictions maintain limits on how tall you can build. Depending on the specifics of your location, these regulations (also termed “district height standards”) may constrain you from building your second floor walls quite as tall as you would like. More likely they will constrain your roof pitch to a certain maximum, thus limiting its ability to contribute to curb appeal. A more significant factor is floor area ratio (FAR), the ratio of a building’s total floor area (gross floor area) to the size of the piece of land upon which it is built. FAR regulations will therefor limit just how much second floor area you may be allowed to build.

Floor Area Displaced by Stairway
Expanding your home vertically will require the provision of a staircase, thus reducing the amount of functional square footage resulting from the build. The requisite stairway can easily eat up 160 to 240 square feet of valuable real estate over both floors. If your first floor currently already has sufficient interior space in the vicinity of the front entry, you can put the staircase here. Most likely this is not the case, so you will need to work with your architect to design a suitable solution to locate your new stairway.

For Further Reading:
• Rocket Mortgage has published an article for those considering to add onto their home at: https://www.rocketmortgage.com/learn/adding-an-addition-onto-your-house.
• “6 Different Types of Home Additions and How to Choose One”, an article at The Spruce, can be read at: https://www.thespruce.com/types-of-house-additions-1821124.
• Better Homes and Garden’s article, “Everything You Should Know About Adding a Second Story to a House” is available at: https://www.bhg.com/home-improvement/remodeling/additions/second-level-home-additions/.

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