ADU vs. Addition: Living Space Classification

Accessory dwelling units (ADUs) are auxiliary homes situated on the same property as your primary residence. They feature a separate entrance, a kitchen or kitchenette, a sleeping area, and a bathroom zone. On the other hand, room additions involve expanding your existing home and do not necessarily imply the presence of living space for all human needs.

Seeking to add extra living space to your property but don’t know what to choose? In this article, we’ll explore both options in order to find out which one suits your needs better!

ADUs are self-contained living spaces with their own entrance, no matter the type. It means you or your family members can live in an ADU without using your main house for any purpose. ADUs are also subject to local building codes and regulations, which may differ from one city to another.

Accessory Dwelling Unit Types

Accessory dwelling units (ADUs) differ in size, layout, and construction method. Here are the most common ADU options you can order from almost any ADU builder:

• Attached Unit

Property owners may find it tricky to distinguish between attached ADUs and room additions. The difference lies in the fact that attached ADUs, although adjacent to the main house, function as completely separate living spaces. Despite their physical connection to the primary residence, they have a separate entrance, their own kitchen, bedroom, and bathroom, creating a self-sufficient residential area.

• Detached ADU

Detached ADUs are completely standalone structures. Typically, they are larger than attached ADUs and possess their own utility connections (gas, water, electricity, and HVAC systems). Detached units are private and autonomous garden cottages suitable for long-term living, whether intended for rental purposes or accommodating adult children.

• Garage Conversions

To build such an ADU, you use an existing structure, such as a detached garage or a large barn. It doesn’t require significant investment because you utilize underused construction already built on your land. You only need to transform it and add new components and features to ensure comfortable and independent living.

Benefits of Accessory Dwelling Units

When planning smaller homes located on the same property as your main house, it’s vital to consider your future needs. That’s because the ADU size, layout, and designs incorporated into the floor plan may vary widely if you want a granny flat or livable space for remote work.

There are a plethora of ADU applications we can discuss, though the most popular are:

• Creating additional space for daily needs

One of the purposes ADU construction serves is to increase functional space. An extra backyard cottage for aging parents or extended family members provides flexible living arrangements while elevating the overall capacity of the property.

• Using it as a guest house

Guest houses are a popular choice when there’s not enough available space in the existing home. Does it sound good that you don’t need to huddle in the same house, crowding into the kitchen, and queuing for the bathroom? Guests (and your family members) will very much appreciate the comfort and privacy that a completely separate living space provides all the residents with.

• Building an ADU as a separate rental property

With an ADU, you can generate rental income. Since the only difference with a traditional house is size, many tenants will find a small garden cottage alluring, especially if the rental unit offers all the conveniences. This additional living space can easily bring you a couple of thousands of dollars per month, covering some of your life expenses or mortgage payments.

• Making a good investment results in increased property value

Why raise the property value? When you sell the property with an ADU, you can expect a higher return on your investment. The reason behind this is that many real estate market players consider properties with an ADU to be upgraded properties and are willing to pay more for them.

• Complementing your property with extra space for occupation or pastime activities

If you have no plans for immediate resale or rent, you can use an ADU for something else. By building an ADU, you receive more space that you can temporarily use for storage, sports, art, music, watching films, or remote working. Organizing dedicated spaces in a unit outside your primary home allows for a conducive setting without compromising your main living quarters.

Room Addition

As we learned, room additions involve expanding the existing primary residence rather than building a separate space nearby. In contrast to creating a new space, it’s more a prolongation of the existing one. For instance, if you need an extra bedroom but lack square footage, it’s not mandatory to build a whole new house. Home expansion services allow for adding a new room without incurring excessive costs.

Benefits of Room Additions

If you opt for room additions, you’ll be able to enjoy such positive improvements to your property as:

• additional space for family or guests;
• expanded square footage that leads to enhanced property value;
• adapting spaces for recreational needs, work, or study;
• opportunity for rental income;
• avoiding inconveniences in daily life;
• cost-effective and disruption-free way to perform a home improvement.

As you can see, many of these advantages mimic those of ADUs. If you need to house an elderly family member, receive rental income, or provide your guests with more or less independent living space, you can use any of them. However, there are several significant factors that separate ADUs and room additions.

ADUs or Room Additions: Main Differences

Despite similarities, each of these options offers distinct advantages and constraints. To make an informed decision about which one to choose, let’s delve into the details of their construction and use.

ADUs and room additions vary due to such factors as:

• Status

By building an ADU, you gain a separate structure that can function on its own. As for room addition, it’s an extension integrated into an existing space of your house. Room additions cannot operate as self-sufficient houses. They are extra rooms, not extra homes.

• Size

While ADUs can sometimes reach as much as 1000–1200 sq. ft., room additions generally restrict themselves to 500 sq. ft. max (they can be larger, but it’s not as common). However, even internal ADUs or small attached ADUs do not count as existing house parts since you can use them separately from the house in question.

• Regulations

Both ADUS and room additions require going through the permitting process. They’re also both subject to local regulations. Yet, obtaining a building permit for an ADU is generally a more streamlined process than obtaining a permit for room addition, thanks to newly adopted laws. Besides, local zoning regulations for ADUs are stricter than for room additions, but the complexity of the structural modifications to the house that additions need may also influence compliance.

• Time, Money, and the Construction Process

Constructing a separate living space like an ADU is typically costlier and more time-consuming than that of a room addition. Nevertheless, home additions require more structural work than an ADU, which can also entail an extended timeline and increased expenses.

All in all, the pros of these structures vary depending on the particular layout and the intended use of the new space. Both ADUs and room additions have their respective pitfalls, and the only way to choose the appropriate option is to understand the features of your property and the desired result.

Frequently Asked Questions — FAQ

Is it cheaper to add on or build an ADU?

The cost of building an ADU is contingent on its size, design, and material use. It beats home additions in two aspects: it does not incur the same tax consequences for the main house, and no possible renovations are mandatory for the primary home. Also, renting an ADU out is a more popular solution, so you can return construction costs over time.

What is the difference between an addition and an ADU?

They differ in purpose: ADUs are more suitable for independent living, while additions are means to expand the existing house, such as adding a new bedroom, creating a bigger bathroom, or a larger kitchen. Besides, they are not alike in a legal sense. Additions are integral parts of the primary dwelling, while ADUs are secondary dwellings autonomous from the main home.

What’s one drawback of an ADU in comparison with a room addition?

One of the biggest ADU drawbacks in comparison with a room addition is property restrictions. If you have insufficient space on your land or non-reduced setbacks according to local regulations, it may pose a difficulty for ADU building, making it problematic or even not feasible. Also, in some regions, permit fees or construction costs may be too high, which can potentially negate ADU benefits. If your only purpose is to expand space, a room addition is a better fit.

Is it better to build an ADU or buy a house?

When building a new house, you usually pay not only for the house construction but also for the land. With an ADU, you place your new small home on the same property, saving extra costs. ADU can potentially produce rental income and compensate for construction costs as time passes. Moreover, ADUs offer more flexible living arrangements than traditional homes, so if you don’t plan to change locations, ADUs are a good solution.