How Much Do Nonna Homes Cost?
Last Updated on January 26, 2025
Written by CPA Alec Pow | Content Reviewed by CFA Alexander Popinker
Nonna homes, also known as accessory dwelling units (ADUs), are gaining popularity across the U.S. as an affordable and flexible housing solution. But for homeowners considering adding a Nonna home, one major question looms: how much will it really cost?
The cost to build a Nonna home can vary widely based on the size, construction type, materials, labor, permits, and various other factors. In this comprehensive guide, we’ll break down the main elements that shape your budget so you can make informed decisions when planning a Nonna home project.
Whether you’re looking to house extended family, generate rental income, or simply expand your living space, understanding Nonna home costs is an essential first step.
How Much Do Nonna Homes Cost?
The cost to build a Nonna home can vary widely, with basic prefabricated units starting around $50,000 on the low end and elaborate custom-designed homes with premium finishes reaching $250,000+ on the high end, but typical pricing for a moderately sized 400-800 square foot ADU with cost-conscious choices in materials and features often falls between $80,000 to $150,000.
While exact costs vary widely based on specific plans, the following core factors drive pricing:
Type of Construction
There are three main construction approaches, each with different cost considerations:
Prefabricated Nonna Homes
- Most budget-friendly option, with small units starting around $50,000
- Factory-built for efficient construction, reducing onsite labor
- Fast installation timeline, sometimes under 3 months
- Limited customization; must accommodate factory specs
Modular Nonna Homes
- Provide a middle ground, averaging $75,000 to $130,000
- Modules built offsite allow some level of customization
- Still faster than custom building, typically 3 to 5 months
- Transporting modules adds logistics expenses
Custom-Built Nonna Homes
- Greatest design personalization, but at a premium
- Costs often exceed $150,000+
- Construction occurs fully onsite over 6-12 months
- Ability to match main home with high-end details
Generally, prefab and modular options provide the most budget control, while custom builds offer ultimate personalization.
Size and Layout
The intended square footage and floorplan will significantly influence pricing:
- Small 1-bedroom units around 400 sq. ft. typically cost $80,000 to $110,000.
- Larger 2–3-bedroom units from 600 – 800+ sq. ft. range from $130,000 to $200,000+.
- Expanded layouts require more materials, labor, foundation, and roofing.
Carefully prioritize needs rather than going overboard on size.
Materials and Finishes
Upgrading fixtures and finishes adds up quickly:
- High-end materials like quartz countertops, hardwood floors, or tankless hot water can add $15,000 to $30,000+ to the price tag.
- Opting for budget-friendly materials such as laminate counters, vinyl plank floors, and electric water heaters saves substantially.
Focus splurges only where they truly enhance daily function and enjoyment.
Labor and Installation
Local contractor rates and professional fees vary:
- In high-cost metro areas, skilled labor accounts for 40-60% of the total price.
- In rural or more affordable markets, experienced contractors charge 15-25% less for comparable work.
- Firms specializing specifically in ADUs are best to optimize pricing and avoid pitfalls.
Government Permits, Fees and Utility Hookup Costs
These expenses add up quickly:
- Municipal permitting, inspections and zoning checks average $8,000 to $15,000 per ADU project. Complex approvals cost more.
- Site preparation like grading averages $15,000 to $35,000 depending on terrain and drainage factors.
- Connecting and metering electrical, water and sewage ranges from $10,000 to $25,000 based on proximity to main home’s utilities.
- Added property value may increase annual taxes by $500 to $2,000+, depending on local assessment practices.
Accurately estimating these fees in your budget prevents sticker shock.
According to a review on Yelp, potential clients have received quotes ranging from $95,000 for garage conversions to approximately $125,000 for a 250 square foot unit. These prices reflect the comprehensive services offered by Nonna Homes, which include architectural design and construction management.
Another source, Nonna Homes’ official website, emphasizes their commitment to custom builds and mentions that costs can vary based on specific client needs. While they do not provide exact pricing on their site, they encourage prospective clients to contact them for detailed estimates tailored to their projects.
A report from Nonna Homes ADU Builder states that they focus on creating high-quality, cost-effective ADUs. They highlight that their pricing is competitive but do not specify exact figures, suggesting that interested individuals should inquire directly for personalized quotes based on their requirements.
According to a discussion on Facebook, Nonna Homes also offers financing options and grants that can help offset costs. They mention a $20,000 grant available for qualifying projects, which can significantly reduce the overall expense of constructing an ADU.
Lastly, an overview from Instagram highlights customer testimonials praising the affordability and quality of the builds provided by Nonna Homes. Clients have noted satisfaction with both the process and the final product, indicating that while costs may be higher than some alternatives, the value received justifies the investment.
What Are Nonna Homes?
Nonna homes are private, self-contained residential units built on the same grounds as an existing single-family home. They go by many names – granny flats, accessory dwelling units (ADUs), backyard cottages, secondary suites – but all refer to a smaller, independent structure meant to supplement the main house.
Nonna homes are surging in popularity due to several key trends:
- Affordable housing shortages – Nonna homes help increase density on existing land.
- Aging populations – They allow extended families to live together while maintaining privacy.
- Income generation – Nonna homes can be rented out for extra income.
- Flexible living spaces – They accommodate changing needs over time.
Prefab, Modular and Custom Nonna Units
While prefabricated options provide the most cost control, modular and custom buildings offer added flair:
Prefabricated Nonna Homes
Pros
- Start around $50,000 for no-frills units
- Extremely fast installation, sometimes under 1 month
Cons
- Limited size options and layout personalization
- Industrial aesthetic lacks character
Cost range: $50,000 – $85,000
Modular Nonna Homes
Pros
- Balance of efficiency and personalization
- Often $75,000 to $130,000 for high quality
Cons
- Some dimensional constraints remain
- Transporting modules expensive
Cost range: $75,000 – $130,000
Custom-Built Nonna Homes
Pros
- Design flexibility limited only by imagination
- Can architecturally match main home
You might also like our articles on the cost of building an ADU, shouse, or tiny house.
Cons
- Much higher cost, easily exceeding $150,000
- Lengthy 6–12-month construction timeline
Cost range: $150,000 – $250,000+
Assess your budget tradeoffs and aesthetic goals to select the optimal build approach.
Hidden Costs and Additional Fees
Beyond just construction, other Nonna home expenses add up quickly:
Permits and Zoning Fees
- Municipal permitting, zoning checks, and inspections typically cost $8,000 to $15,000 per ADU project.
Site Preparation
- Grading, excavating, land clearing can add $15,000 to $30,000 depending on terrain and existing infrastructure.
Utility Installation
- Hooking up water, sewer, gas, and electric lines often runs $10,000 to $20,000 based on complexity.
Impact on Property Taxes
- Increased assessed home value may raise property taxes by $500 to $2,000+ annually.
Accurately estimating these fees ensures no budget surprises down the road.
Regional Cost Differences
Where you live significantly influences pricing:
- In high-cost areas like California, Nonna homes run $75,000 to $125,000 higher than other regions due to extremely high land values and labor costs. Permits and fees also cost more.
- States like Texas, Georgia or North Carolina offer average pricing up to 35% below coastal city rates for similar quality builds.
- Midwestern and Southern states tend to have lower regulatory hurdles, material expenses and professional charges than the West Coast and Northeast.
Always obtain quotes from local builders before setting expectations, as costs fluctuate market to market. Carefully research average pricing in your city or neighborhood.
Financing Options
Despite potential cost savings versus conventional homes or condos, funding ADUs still requires capital:
ADU-Specific Construction Loans
- Offered by specialized lenders familiar with these projects
- May finance up to 100% of total costs
- Competitive interest rates around 4-6%
Cash-Out Mortgage Refinancing
- Tap into your existing home equity at lower fixed rates
- Receive funds in lump sum to pay builders
Home Equity Lines of Credit (HELOCs)
- Revolving credit for flexible draw amounts
- Useful for modular building with progress payments
Personal Loans or Credit Cards
- Higher rates but faster approval if credit sound
- Best for smaller projects only
For affordable monthly payments, construction loans and refinancing your mortgage are ideal options to cover major ADU projects.
Controlling Costs
Every project comes with opportunities to save:
- Prefab and modular options cost much less than custom builds.
- Smaller square footage makes a big difference in materials and labor.
- Work with experienced local ADU contractors to avoid expensive mistakes.
- Limit unnecessary luxury finishes that quickly drive up expenses without adding core value.
- Be ready to complete basic interior painting and decorating yourself.
Real-World Home Cost Scenarios
To provide tangible illustrations, here are two sample builds:
400 Sq. Ft. Prefab ADU
- $68,000 total cost
- $50,000 base prefab unit
- $8,500 permitting fees
- $4,500 utility connections
- $5,000 budget finishes
850 Sq. Ft. Custom ADU
- $248,000 total cost
- $185,000 custom building
- $22,000 high-end finishes
- $15,000 expanded foundation
- $18,000 permitting and site prep
- $8,000 premium HVAC system
The takeaway? Construction approach and size have an immense impact on your final budget.
“We recently built a 500 square foot ADU in our backyard for my elderly father-in-law using a modular construction approach. By optimizing the layout and being smart about finishes, we kept total costs under $95,000 in our California neighborhood.” – Phil Santos, Homeowner
Final Words
Constructing a Nonna home is a complex endeavor with costs spanning well beyond the walls to include permitting, site work, utilities, and more, but thorough planning centered on prioritizing space and features wisely can help realize this rewarding investment for under $100,000 in many housing markets across the U.S.
With an understanding of the cost factors and financing options, homeowners can make informed tradeoffs to add invaluable living space tailored to their family’s evolving needs and budget.
Answers to Common Questions
Can I finance my ADU?
Yes, there are several options to finance the construction of an ADU:
ADU-specific construction loans offered by banks and credit unions allow borrowers to fund the full cost of their ADU build.
Cash-out mortgage refinancing lets homeowners leverage their existing home equity at competitive fixed rates.
Home equity lines of credit (HELOCs) provide revolving access to funds over time.
Personal loans through banks or online lenders supply another financing avenue..
Government grants and development incentives for ADUs exist in some municipalities to promote affordable housing.
How long will it take to finish my ADU?
The timeline to complete your ADU construction largely depends on the method:
Prefab ADUs can be installed extremely quickly, sometimes in under 1 month from permitting to completion.
Modular ADUs typically take 2 to 3 months end-to-end.
Custom-built ADUs have the longest timelines, averaging 6 months to 1 year.
Factors like permitting timeframes, contractor workload, weather delays, and unexpected complications also impact overall timelines across all ADU types.
Where can I build my ADU?
ADUs can generally be built in the following locations:
Within existing homes like basement or attic spaces, through interior renovations and conversions.
Attached to the primary residence as an extension, often sharing utilities and foundation systems.
In the backyard as a detached stand-alone structure, essentially a second miniature home on the lot.
Above garages, transforming unused rooftop space into a living area.
On driveways or paved surfaces, installing a mobile prefab unit in the front or side yard.
Municipal zoning ordinances ultimately determine allowable placement on a given residential property based on factors like lot size, setbacks, FAR limits, and aesthetic impacts. Consulting local codes is essential.
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