What is the Difference Between an ADU and a Guest House

Nowadays, many people build accessory dwelling units (ADUs). These constructions may significantly enhance the value of your property lot. Also, they’re very versatile and can belong to several different types. One of these types is a guest house, also known as a “casita” or a pool house.

In this material, we’re going to compare regular ADUs and guest houses. We’ll tell you about the main characteristics and advantages of both guest houses and ADUs. If it’s difficult for you to pick from these two variants, our article can be useful for you!

Accessory Dwelling Unit (ADU)

First of all, let’s look at regular accessory dwelling units. An ADU (also known as a granny flat or in lawsuit) is a secondary housing unit that shares the same property with the main house. Usually, it has all the conveniences required for a separate living space: a bathroom, a kitchen, one or two bedrooms, electricity, and plumbing. This makes it suitable for living as a primary residence.

Depending on their characteristics, ADUs can belong to several categories:

1. Detached. Such an ADU is a full-fledged single-family home that’s completely separate from the main residence. Typically, it’s larger and more expensive than other ADUs and offers better privacy. Oftentimes, homeowners build detached ADUs for their aging family members. In most cases, plumbing, electricity, and other amenities in such houses are also independent of the primary residence. A detached ADU is perfect for multi-generational living or additional rental income;
2. Attached. It’s an ADU that has a common wall with the main house. It may have a shared or separate entrance. In some cases, it also has direct access to the main house utility systems or even shares a roof with it. Usually, such ADUs are smaller than detached ones. People also construct attached ADUs as living spaces for their relatives, especially if they need constant care. In addition to that, homeowners often convert them into art studios or personal cinemas;
3. Internal. It’s a separate living space located inside the main house. An internal ADU can be an attic or a basement apartment. This is a great option for those who have unused existing space in their residence;
4. Converted. This accessory dwelling unit is perfect for those who’ve got an existing structure on their lot (for example, a garage) which they don’t use. Just as an internal ADU, a converted one needs much less time and money to build than attached and detached units. This makes it very popular among homeowners in California.

An ADU can have plenty of different purposes. You can use it for rental income, convert it into a mini-cinema, personal gym, office for an online job, living space for your elderly relatives, or a place for guests. There’s even a special subtype of ADUs, called guest houses. Let’s have a more detailed look at them.

Guest House

A guest house is an accessory structure specifically meant for accommodating guests. Like a classic ADU, it stands on the same property as the main house. However, it’s usually smaller. Some such buildings are more like little rooms than full-fledged houses. But they also have everything necessary for an additional living space. Even if a guest house has too limited space to have its own kitchen and a full bathroom, it still has a half-bathroom and a kitchenette. It’s important to mention that a guest house cannot belong to an attached or converted type. The only type that it can be is a detached ADU.

If you’ve got a guest house, you can invite your friends to stay with comfort and privacy in a real backyard cottage. An amazing possibility, isn’t it?

Size Limitations of ADUs and Guest Houses

Since guest houses aren’t meant for long-term living, they typically have smaller sizes than classic ADUs. In lots of areas, their minimal size restrictions are much softer. For instance, their square footage often can be less than 800 sq. ft. In addition to that, in some places, ordinary ADUs need owner occupancy — but guest houses never require it.

Local Zoning Laws

Zoning regulations regarding ADUs and guest houses are also different. In both cases you’ll need to comply with some restrictions, such as lot coverage or various setbacks. They mainly depend on the place and construction type. According to the local laws of some areas, guest houses are nothing more than additions to the main homes. So, regulations about them are less strict there.

Construction Planning

Any separate living space requires utility systems — for example, plumbing and electricity. However, regulations regarding them differ in classic ADUs and guest houses. Usually, accessory dwelling units require more in-depth planning. Its list of safety and health rules is considerably longer. Also, it needs more thoroughly-built infrastructure. This makes a guest house quicker and less costly to create.

Expenses

The price of building any house varies depending on many factors – its size, type, quality of materials, etc. In most cases, classic accessory dwelling units cost more because of their self-contained living space status, more thorough planning, and better materials. However, an ADU also can be rather cheap — especially if it’s a prefab unit or a converted garage.

In many areas, it’s possible to get a construction loan for an ADU via ordinary mortgage variants (though there are lenders with extra requirements about ADUs). Moreover, some areas offer special support programs that alleviate their financing.

If you’re going to build a guest house, a suitable option for you is a HELOC, which stands for home equity loan or line of credit. But, on the other hand, since this structure is more affordable and cost-effective, some homeowners use their own budgets to pay for it.

ADUs and Guest Houses: Main Advantages

Both an ADU and a guest house have their own significant benefits. A separate accommodation on your property gives you lots of extra possibilities. With it, you can generate rental income, provide additional space to your friends, and so on. Also, it makes your property much more valuable than with only one existing home.

Guest houses offer the following benefits:

• Rental income potential — a guest house can also be a source of a steady rental income. Often, people use guest houses as short-term rentals;
• Privacy for property owners and their friends who come to visit them. Your guests will get their own space without compromising your comfort and that of your family members.

As for accessory dwelling units, they have such advantages as:

• The possibility of passive income. Long-term rental housing is one of the most widespread purposes of ADUs;
• Living near your elderly parents and having the possibility to easily access them if they need treatment. An ADU can make caring for your aging family members much easier. At the same time, you and they will still have a private space, which would be impossible if they lived in the same home with you.

An accessory dwelling unit is a very multifunctional structure. People use ADUs as home offices, personal gyms, art studios, mini-cinemas, additional spaces to relax, and so on.

A Guest House or an ADU: What’s Better

Are you still in doubt about what to select — an ADU or a guest house?

In this case, think about the following things:

1. The size of your property lot. If it’s large enough, it’d be better to choose an ADU, and in case it’s small, a guest house may be preferable;
2. Your budget. They’re both affordable housing options, but accessory dwelling units (ADUs) typically cost more than guest houses (although this isn’t the only factor that affects their price);
3. The type of construction that you want to build. A guest house can only belong to a detached type, while ADUs can be different: attached, detached, converted, and so on;
4. The purpose of your desired building. In case you want a potential rental income source or a permanent residence for your aging parents, a regular ADU would be more suitable. If you’re going to construct it to accommodate friends, we’d advise you to choose a guest house.

The Conclusion

Both guest houses and ADUs have their own benefits. To pick the best option for yourself, you’ll need to know their main distinctive features. Do you need a house for your elderly parents or a place where your guests can spend a night? This question needs careful consideration. Even if the answer seems clear to you, we’d recommend you to consult with real estate professionals to know all the possible nuances.

In addition to that, you’ll need to read all the local regulations and building codes and learn about property taxes and other such things. Try to become maximally informed – it will help you to complete the permit process and avoid many grave errors. If you don’t have the skills and qualifications that are necessary for construction, contact a team of competent building specialists. At first sight, it may seem pricey, but it’s a much more cost-effective variant because it will help you prevent making any expensive corrections in the future.

We sincerely hope this article was useful for you, and we wish you success in constructing a guest house or an accessory dwelling unit!

Frequently Asked Questions — FAQ

What is the difference between a guest house and an ADU in California?

A guest house is also an accessory dwelling unit but considerably smaller, cheaper, and meant mostly for short-term guest accommodation. Meanwhile, ADUs can have various purposes — houses for aging relatives or adult children, rental units, miniature cinemas, gyms, distance work offices, and so on.

Unlike an ADU, a guest house often doesn’t have a full bathroom and a kitchen. However, it’s still a comfortable housing unit with all conveniences, including bathing and cooking facilities. ADUs can have different types (attached, detached, converted, etc), but a guest house can only belong to a detached type.

Can I build a guest house on my property in California?

Of course! California’s local authorities consider guest houses ADUs. And they don’t only allow homeowners to build ADUs, but also promote them to increase urban development and solve the housing shortage problem. However, to construct a guest house (as any ADU) you’ll need to comply with all the relevant regulations, such as zoning rules and building codes.

What’s the main drawback of an ADU?

Guest houses and ADUs have numerous domestic and financial benefits. However, they also have a disadvantage — they significantly diminish the size of your backyard. For some homeowners, it’s not a problem at all, but for others, it’s a valid reason to give up an idea of constructing a secondary dwelling unit on their property.

What is the definition of a guest house?

A guest house is a tiny accessory dwelling unit (ADU) situated on the same property as the main house. Despite its small size, it’s got all the conveniences needed for a comfortable short-term accommodation — electrical and plumbing systems, a half-bathroom and a kitchenette.