“Additional Dwelling Unit” or “Accessory Dwelling Unit”—What’s the Difference?
If you’ve searched online for an Additional Dwelling Unit, you’re not alone. Thousands of homeowners use that phrase every month to describe what professionals call an Accessory Dwelling Unit (ADU) – a small, self-contained home built on the same property as a primary residence.
Whether you call it an Additional Dwelling Unit, backyard home, granny flat, or in-law suite, the goal is the same: a second home that adds flexibility, value, and income potential to your property. And when it comes to how you build it, modular construction is quickly becoming the most efficient and dependable approach.
What Exactly Is an Accessory Dwelling Unit (ADU)?
An Accessory Dwelling Unit (ADU) is a fully functional home – typically including a kitchen, bathroom, and living area – that shares a lot with a main residence. ADUs can be detached backyard cottages, attached extensions, or apartments over garages.
Cities and counties throughout the Pacific Northwest are promoting ADUs as a sustainable solution to rising housing costs. Homeowners gain usable space and added value, while communities benefit from subtle, low-impact housing growth.
When searching online, remember: “Accessory Dwelling Unit” is the official, code-recognized term used by cities, lenders, and builders.
Why Homeowners Are Turning to ADUs
• Rising home prices and limited inventory
• Families seeking multi-generational living options
• Passive rental income opportunities
• Relaxed zoning and expedited ADU permitting
Homeowners who want speed, simplicity, and predictability are turning to modular ADUs – factory-built homes that make the process smoother from start to finish.
The Benefits of a Modular ADU
1. Faster Build Times
Your ADU is built indoors while your site work happens simultaneously. That means move-in ready much faster than with a traditional stick-built home.
2. Superior Quality
Factory construction means every stage is monitored, inspected, and built with precision tools and consistent oversight – unaffected by weather delays with materials having no exposure to weather as well.
3. Cost Predictability
With fixed pricing and minimal variables, modular ADUs eliminate the surprise expenses that often derail traditional construction.
4. Sustainability and Energy Efficiency
Less material waste, tighter seams, and energy-efficient design make modular ADUs eco-friendly and cost-effective to operate.
5. Turn-Key Simplicity
Many modular builders handle the entire process – design, permitting, transportation, and installation -under one contract. This makes the process simple for property owners, avoiding the headache of dealing with these processes and different contractors.
The Financial Advantage of Building an ADU
Adding an ADU is one of the smartest financial decisions a homeowner can make:
- Property value boost: Adds 20 to 30% or more to your property’s resale potential.
- Rental income: Long-term or short-term rentals can create steady monthly revenue.
- Flexibility: Use it as a guest house, home office, or caregiver suite.
- Tax and financing benefits: Many states offer ADU-friendly loan programs and multi-generational property tax exemptions.
Example: A Clark County homeowner installed a 600-sq-ft modular ADU for under $220,000 and now rents it for $1,800/month – earning consistent returns year-round.
Common Misconceptions About Modular ADUs
Myth: Modular ADUs are mobile homes.
Fact: Modular ADUs are built to the International Residential Code (IRC) – the same standard as site-built homes – and installed on permanent foundations.
Myth: Modular homes all look the same.
Fact: Modern modular ADUs come in a range of designs, finishes, and materials to match your home and neighborhood.
Myth: Permitting takes forever.
Fact: Many jurisdictions now have dedicated ADU programs and faster approvals, especially for modular housing.
How to Choose the Right Modular ADU Builder
Look for a partner that offers:
- Factory-built experience and local code expertise
- Transparent, all-inclusive pricing
- End-to-end project management (permitting through delivery)
- Proven results and satisfied client testimonials
The right builder will coordinate every step so you can focus on how you’ll use your new space.
Conclusion: The Smarter Way to Build Small
Whether you searched for an Additional Dwelling Unit or the proper term Accessory Dwelling Unit (ADU), the vision is the same – a high-quality, efficient living space that enhances your property and lifestyle.
A modular ADU delivers faster build times, exceptional quality, and lasting value. It’s the modern way to expand your space without the stress of traditional construction.
Ready to explore your options?
Start your free property evaluation and see how easily a modular ADU can become your next great investment.