ADU Manufactured Homes in San Diego: Are They Right for You?

What is a Manufactured ADU?

A manufactured ADU is one that’s built entirely off-site in a controlled factory environment, then delivered as a single, complete unit — almost like a mobile home — and dropped onto a foundation. They are considered a type of prefabricated construction.

Prefabricated construction is construction that’s done off-site, then assembled or delivered in parts to the final destination.

Prefabricated construction can be either modular or manufactured.

• Modular: The structure is delivered in pieces and assembled on-site
• Manufactured: The structure is delivered as a single, complete unit

Modular homes can come in a variety of shapes and floor plans, while manufactured homes are typically rectangular in shape.

• Single-wide manufactured homes: A rectangular-shaped unit that’s 1200 square feet or less. Note that 1200 square feet is the maximum ADU size in most California cities.
• Double-wide manufactured homes: A unit that combines 2 single-wide manufactured homes to create a structure that’s between 1800 and 2400 square feet

The pros of choosing a manufactured ADU include:

• Lower construction costs
• Faster construction time

The cons of manufactured homes include:

• Few options for customization
• Lower return on investment
• Fewer financing options, with most requiring a personal loan

Manufactured ADUs offer a cost-effective solution, but their design flexibility is limited. Consider your property’s layout and aesthetic goals before committing.

Can a Manufactured Home be an ADU?

Yes, in some cases, a manufactured home can qualify as an ADU. It depends on where you live and how your manufactured home is built.

At a minimum, a manufactured ADU must sit on a foundation and contain a bedroom space, a kitchen or kitchenette, a separate bathroom, and a separate entrance. It also can’t exceed 1200 square feet and must follow certain zoning laws and fire building codes, as well as all Title 24 requirements.

However, some local governments may place additional restrictions when it comes to manufactured homes specifically. For example, they may require that they match the exterior design or appearance of the primary home. HOAs can have similar requirements or may even ban manufactured ADUs outright to preserve the curb appeal of the neighborhood. Individual cities may also do this.

The good news is that state laws are continuing to remove barriers to ADU construction, including on manufactured homes. To see what’s allowable in your city or county, contact your local building department.

Not all manufactured homes qualify as ADUs. Ensure compliance with local zoning laws, foundation requirements, and architectural guidelines to avoid setbacks.

Are Manufactured Homes Considered Real Estate?

Yes, so long as a manufactured ADU is installed on a permanent foundation and meets local building requirements, it can be considered real property. This is true for California and most states in the country. It also means that it can be factored into your property’s value and impact your overall property taxes, though manufactured homes are generally associated with lower return on investment, which leads to less overall impact on your property taxes.

If a manufactured home isn’t installed on a permanent foundation, it may be considered a mobile home or a tiny home, depending on the city, both of which come with different regulations and building codes. Some counties may even ban this type of construction outright. To understand the restrictions that may exist concerning manufactured homes in your city, contact your local building officials.

Manufactured ADUs can be classified as real estate if installed on a permanent foundation and meet local building codes. This impacts financing options, property taxes, and long-term value. Always verify local regulations before investing.

Why Do People Choose to Buy Manufactured ADUs?

The main reasons people choose to buy a manufactured ADU include:

• Lower construction costs. Since manufactured homes are built entirely off-site and often in conjunction with many other manufactured homes, the labor costs and material costs are far less than with traditional builds. This type of building process can have a significant impact on the total project budget, especially when you consider that labor may account for as much as 50% of a total construction project budget.
• Minimal disruption to the primary residence. Since manufactured ADUs are built entirely off-site and delivered to their final destination in one piece, there’s minimal disruption from construction. There may need to be some site assessments, prep work, and foundation pouring, but when you consider that a typical concrete slab is poured in just one day, this on-site work is minimal compared to traditional construction methods.
• The need for extra space quickly. Sometimes, unforeseen life circumstances mean that a homeowner needs to complete their ADU project as quickly as possible. Perhaps they need to accommodate an aging parent, for example, or move an adult child from the primary dwelling unit into a secondary home as soon as possible. This is where prefab ADUs can help, giving homeowners the liveable space they need on a short timeline.
• Little need for customization. For homeowners who don’t have much need for customization beyond the basic floor plan, manufactured ADUs can be an appealing option. The lack of variety of floor plans and standardization of overall design is what ultimately makes these kinds of ADUs so affordable.

Manufactured ADUs provide quick additional space, but their design limitations may impact future resale value. Evaluate your long-term needs before deciding.

Manufactured ADUs vs. Stick-Built ADUs: A Detailed Comparison

Despite the benefits we just mentioned for manufactured ADUs, especially when it comes to budget and timeline, they aren’t the right choice for everybody. There are limitations involved. Permitting, city regulations, durability, and customization limitations may ultimately make a stick-built ADU the better choice for your property and your intended use.

One last point to consider: while manufactured ADUs typically provide lower labor and construction costs, transportation is a hidden cost to consider. These transportation costs can be significant, as special trucks and other equipment are required to ship these units to your house. Make sure to ask about any transportation costs associated with your build before you sign any contract with a manufactured ADU builder.

Key Factors to Consider When Choosing Between Manufactured and Stick-Built ADUs

Ultimately, the decision to go with a prefabricated accessory dwelling unit or stick-built ADU typically comes down to 4 key factors: budget, timelines, intended use, and long-term value.

When deciding between manufactured and stick-built ADUs, consider budget, timeline, customization, and long-term value. Stick-built ADUs offer more durability and higher ROI, while manufactured ADUs provide a faster, lower-cost solution.

Budget

For homeowners with a limited budget and limited financial options, a manufactured ADU can be a great solution to add more livable space to the property.

To put it in perspective, a detached, stick-built ADU that is 1200 square feet will typically cost homeowners $350,000+. Compare this with a manufactured home of the same size, which can cost as little as $150,000 to $200,000.

One important thing to note is that manufactured homes don’t stand up to extreme weather events (hurricanes, floods, fire, etc) as well as stick-built homes do. If you live in an area prone to natural disasters, this is something to consider. They are also harder to repair after such events than stick built houses – this can lower their lifespan and impact your long-term ROI, so keep your location’s weather in mind.

While manufactured ADUs can lower construction costs, material quality impacts longevity. Prioritize durable finishes to maximize value over time.

Timeline

If you’re in a situation where you need to create additional housing on your property as quickly as possible and every day counts, a manufactured home may be the best way to meet your timeline. From initial order to final delivery and move-in, most manufactured homes take 2 to 4 months to complete.

For what it’s worth, most of our custom floor plan stick-builds are completed within 8-12 months. That means you can get an additional living space that’s completely customized to your needs in less than one year. That includes our initial consultation and the permitting process.

If using a manufactured ADU as a rental, high-quality finishes and functional layouts can attract tenants and justify higher rental rates.

Intended Use

A manufactured accessory home may work as a granny flat, guest house, flex space, or home office space. But if you are looking to use an ADU as a means of additional income, a manufactured ADU may not allow you to charge as much in rent as you would for a stick-built version.

This is because the lack of customization and appeal in terms of design can turn off potential renters, especially in a market like San Diego, where people are searching for a modern design that offers the feel of a traditional home.

Manufactured ADUs significantly reduce construction timelines. However, factor in transportation and site prep costs to avoid unexpected delays.

Long-Term Value

While manufactured homes may involve lower upfront costs, their durability can vary, and homeowners may have to shell out money for more expensive repairs sooner than with custom, stick-built ADUs.

Moreover, these types of ADUs don’t offer the same ROI when it comes to property value. Custom-built ADUs, on the other hand, can increase a home’s valuation by as much as 35%, which is all profit in your pocket if and when you go to sell.

Stick-built ADUs often have better ROI than manufactured ones. If long-term appreciation is a priority, consider construction durability and market trends.

Making the Right Choice for Your ADU in San Diego

At Better Place Design & Build, we have a proven track record of building accessory units that meet all our clients’ needs when it comes to budget, timeline, and design. To see what’s possible when it comes to your ADU project, schedule a free consultation.