Waterfront Duplex with
For Sale
$1,185,000
391 10th Street, Key Colony Beach, FL 33051
Residential, Key Colony, FL
Property Size2,166 SF
Lot Size0.09 Acres
Price / SF$547.09
Days on Market156
Property Features for 391 10th Street
General Information
Property type
Residential
Property subtype
Duplex
Zoning
R-2A - Key Colony Two Fam
Bedrooms
3
Bathrooms
3
Full bathrooms
3
Rooms
Bedroom 3, Bathroom 2, Bathroom 3, Bathroom 1, Bedroom 1, Bedroom 2
Parking features
Open
Patio and Porch features
Deck, Porch
Pets allowed
Yes
Interior features
Storage, Quartz Countertops
Exterior features
Fencing
Fencing
Fenced
Appliances
Washer, Dryer, Dishwasher, Refrigerator, Oven, Microwave, Disposal, Stainless Steel Appliance(s)
Subdivision
Key Colony Bch 1st Addn Amd Plat (53.5)
Directions
From US-1, turn onto Sadowski Causeway. Turn right onto West Ocean Drive. Right onto 10th Street. Property will be on left side with sign out front.
Standard status
Active
APN
00076300000000
Size
2,166 SF
Lot size
0.09 Acres
Taxes and HOA fees
Tax Year
2025
Tax Description
BK 11 NLY 1/2 LT 14 KEY COLONY BEACH FIRST ADDN AMENDED PLAT PB4-11 SHELTER KEY
Tax Annual Amount
6525
Legal Description
BK 11 NLY 1/2 LT 14 KEY COLONY BEACH FIRST ADDN AMENDED PLAT PB4-11 SHELTER KEY
Utilities
Utilities
Cable Available
Cooling system
Central Air
Water front
1
Amenities
deck
Building Details
Year built
1988
Flooring type
Tile, Laminate
Building materials
CBS
Roof type
Metal
Additional Structures
Storage
Listing Agency:
Ocean Sotheby's International · Sotheby's International Realty
(305) 735-4447
Listed By:
Ally Kelley · License #SL3352184
(727) 459-0493
Added: Apr 2
Changed: Sep 3
Last Checked: Sep 4 at 6:06PM
MLS# 619329
Copyright © 2026 Marathon and Lower Keys Association of Realtors. All rights reserved. All information provided by the listing agent/broker is deemed reliable but is not guaranteed and should be independently verified.
Investment Insights
Based on property information with market context.
This CBS half duplex contains 2,166 square feet with three bedrooms and three bathrooms across a two-level layout. The lower level is built above flood elevation and includes a one-bedroom, one-bath suite, additional living space, storage, and access to a wood deck. Upstairs, the home features an open kitchen, dining, and living arrangement, along with a primary suite and a second bedroom with an ensuite bathroom. Interior stairs connect both levels.
The property includes 37.5 feet of dockage and a fenced outdoor area with an open parking space. Construction dates to 1988, with a 2018 standing-seam metal roof, central air, tile and laminate flooring, and quartz countertops. Located at 391 10th Street in Key Colony, the property is near the community’s golf course, tennis and pickleball courts, Sunset Park, restaurants, boat ramp, and marina. Zoning is R-2A - Key Colony Two Fam.
The property includes 37.5 feet of dockage and a fenced outdoor area with an open parking space. Construction dates to 1988, with a 2018 standing-seam metal roof, central air, tile and laminate flooring, and quartz countertops. Located at 391 10th Street in Key Colony, the property is near the community’s golf course, tennis and pickleball courts, Sunset Park, restaurants, boat ramp, and marina. Zoning is R-2A - Key Colony Two Fam.
Key Highlights
- 2,166‑square‑foot half duplex with three bedrooms and three bathrooms
- 37.5 feet of dockage with direct access from the lower‑level living area
- Above‑flood lower level includes a one‑bedroom, one‑bath suite and additional living space
Financial Insights
Estimated NOI and Cap Rate
NOI = area × lease_rate × (100 − vacancy) / 100 × (1 − expense_ratio). Net Operating Income — what the owner takes home each year before mortgage payments and income tax. Effective rent (asking rent minus vacancy losses) minus operating costs (taxes, insurance, maintenance, management).
NOI / Yr
$36,285
Cap rate = NOI / list price × 100. Capitalization rate — annual return on a fully cash purchase, before financing. NOI divided by price. Higher means more income per dollar invested, but usually also more risk or older condition. 5–8% is typical for stabilized commercial property; double digits often signal distressed deals.
Cap Rate
3.06%
Suggested Prices Based on Cap Rates
Cap rates vary significantly by property type, market, and asset quality.
Typical U.S. stable-market ranges:
Multifamily — 4.5% to 6.5% (Class A in primary markets often sub-5%; Class C in secondary markets 6%+)
Industrial / Logistics — 5.0% to 7.0% (compressed heavily in recent years due to e-commerce demand)
Office — 6.5% to 9%+ (wide spread post-2020; CBD Class A vs. suburban Class B varies dramatically)
Retail — 5.5% to 8.5% (grocery-anchored on the low end, unanchored strip centers higher)
Hospitality / Hotels — 7.5% to 10%+ (higher due to operational risk)
Self-Storage — 5.5% to 7.5%
Medical Office — 6.0% to 7.5%
Net Lease (single tenant, credit) — 5.0% to 7.0% depending on tenant credit and lease term
Rules of thumb:
Primary markets (NYC, SF, LA, Boston, DC) trade at lower cap rates than secondary/tertiary markets, often by 100–200 bps (bps, aka basis points; 1 bp = 0.01%).
Class A assets trade ~50–150 bps tighter than Class B, and Class B tighter than Class C.
Cap rates move inversely with price — a lower cap rate means a higher price for the same NOI.
Spread to the 10-year Treasury is a common benchmark; historically 200–400 bps over the 10-year.
Cap Rate 5%
$725,700
$725.7K
Cap Rate 7%
$518,357
$518.4K
Cap Rate 9%
$403,167
$403.2K
Market Conditions
NOI Build-Up for 2,166 SF
Vacancy — income lost from leasable area expected to sit empty during the year, subtracted from gross rent.
EGI (Effective Gross Income) — gross rent minus vacancy losses, the realistic income before paying operating costs.
OpEx (Operating Expenses) — recurring costs to operate the property (property tax, insurance, utilities, maintenance, management); excludes financing and capital improvements.
NOI (Net Operating Income) — income a property generates after operating costs but before financing and taxes.
Gross rent
$55.4K $25.56/SF
− Vacancy
−$3.5K −$1.63/SF
EGI
$51.8K $23.93/SF
− OpEx
−$15.6K −$7.18/SF
NOI
$36.3K $16.75/SF
Area
Monroe County, FL
Vacancy
6.37%
Lease Rate
$25.56 /SF/Yr
Expense Ratio
30.00%
Simulate Cap Rate and NOI
Suggested Prices Based on Cap Rates
Cap rates vary significantly by property type, market, and asset quality.
Typical U.S. stable-market ranges:
Multifamily — 4.5% to 6.5% (Class A in primary markets often sub-5%; Class C in secondary markets 6%+)
Industrial / Logistics — 5.0% to 7.0% (compressed heavily in recent years due to e-commerce demand)
Office — 6.5% to 9%+ (wide spread post-2020; CBD Class A vs. suburban Class B varies dramatically)
Retail — 5.5% to 8.5% (grocery-anchored on the low end, unanchored strip centers higher)
Hospitality / Hotels — 7.5% to 10%+ (higher due to operational risk)
Self-Storage — 5.5% to 7.5%
Medical Office — 6.0% to 7.5%
Net Lease (single tenant, credit) — 5.0% to 7.0% depending on tenant credit and lease term
Rules of thumb:
Primary markets (NYC, SF, LA, Boston, DC) trade at lower cap rates than secondary/tertiary markets, often by 100–200 bps (bps, aka basis points; 1 bp = 0.01%).
Class A assets trade ~50–150 bps tighter than Class B, and Class B tighter than Class C.
Cap rates move inversely with price — a lower cap rate means a higher price for the same NOI.
Spread to the 10-year Treasury is a common benchmark; historically 200–400 bps over the 10-year.
Cap Rate 5%
$725,700
Cap Rate 7%
$518,357
Cap Rate 9%
$403,167
Alternative Uses
Best Use
Multifamily LT 5
$518.4K
$453.6K – $604.8K
NOI $36,285 @ 7.0% cap · market cap 3.06%
Second Best
Apartment 5plus
$480.2K
$420.1K – $560.2K
NOI $33,611 @ 7.0% cap · market cap 2.84%
Theoretical Best
Office A
$871.3K
$762.4K – $1.02M
NOI $60,988 @ 7.0% cap · market cap 5.15%
Zoning and permitted uses should be independently verified with authorities.
Property Analytics
Property Profile
Current Use
Location Intelligence
Trade Area within ½ mile
244
Businesses Nearby
Explore this area
Business Placement
Demographics for 33051, FL
790
Population
1,132
Households
0.7
Avg Household Size
63
Median Age
48%
College-Educated
95%
High-School Grad
0.4 sq mi
ZIP Area
1,975
Density / Sq Mi
$94,531
Median Household Income
$38,860
Median Earnings
$1,849
Median Rent
$834,800
Median Home Value
Market
Vacancy Rate% for Multifamily in South region
Questions? Ask Rey
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Frequently Asked Questions
What type of property is this?
Duplex - CBS construction includes a lower-level suite and open-concept upper living area.
Where is this duplex located?
The property is located at 391 10th Street Key Colony Beach, FL.
What is the asking price?
The asking price for this property is $1,185,000.
What are key features of this property?
This property features: 2,166‑square‑foot half duplex with three bedrooms and three bathrooms; 37.5 feet of dockage with direct access from the lower‑level living area; Above‑flood lower level includes a one‑bedroom, one‑bath suite and additional living space
