Updated Duplex with Metal
For Sale
Under Contract
$594,000
310 3rd Street, Key Colony Beach, FL 33051
Residential, Key Colony, FL
Property Size1,031 SF
Lot Size0.08 Acres
Price / SF$576.14
Days on Market52
Property Features for 310 3rd Street
General Information
Property type
Residential
Property subtype
Duplex
Zoning
R-1A - Key Colony Single
Bedrooms
2
Bathrooms
2
Full bathrooms
2
Rooms
Bathroom 2, Bathroom 1, Bedroom 2, Bedroom 1
Parking features
Open
Patio and Porch features
Porch
Pets allowed
Yes
Interior features
Granite Counter Top, Storage, Walk-in Closet(s)
Exterior features
Rain Gutters, Shed, Storage
Appliances
Washer, Dryer, Dishwasher, Refrigerator, Oven, Microwave
Subdivision
Key Colony Beach (53.5)
View
Water
Directions
US 1 to Sadowski to E Ocean Dr. to 3rd St.
Standard status
Active Under Contract
APN
00072590-000000
Size
1,031 SF
Lot size
0.08 Acres
Taxes and HOA fees
Tax Year
2025
Tax Description
BK 2 N 1/2 LT 31 KEY COLONY BEACH PB3-120 SHELTER KEY
Tax Annual Amount
4710
Legal Description
BK 2 N 1/2 LT 31 KEY COLONY BEACH PB3-120 SHELTER KEY
Utilities
Cooling system
Central Air
Building Details
Year built
1982
Flooring type
Laminate, Tile
Building materials
CBS
Roof type
Metal
Additional Structures
Storage
Listing Agency:
Florida Keys Real Estate Group
(305) 783-3395
Listed By:
Jennifer Hamill · License #3611186
(305) 393-1993
Added: Jul 13
Changed: Aug 28
Last Checked: Sep 2 at 6:06PM
MLS# 620613
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 elevated half duplex at 310 3rd Street offers 1,031 square feet of living space with two bedrooms and two bathrooms. Built in 1982, the residence includes an updated kitchen with granite countertops, a primary suite with walk-in closet and balcony, and a lower-level area suited to additional living or entertaining space. Laminate and tile flooring, central air, interior storage, and a CBS construction system are among the existing features. A new metal roof, rain gutters, shed, open parking, porch, washer, dryer, dishwasher, refrigerator, oven, and microwave are also included.
The property occupies 0.08 acres in Key Colony, Florida, within the R-1A - Key Colony Single zoning district. Nearby community amenities identified for the property include the Cabana Club, waterfront parks, pickleball and tennis courts, a playground, golf, restaurants, and walking paths. The backyard provides outdoor space, while the location places the residence near the recreational and service amenities of Key Colony Beach.
The property occupies 0.08 acres in Key Colony, Florida, within the R-1A - Key Colony Single zoning district. Nearby community amenities identified for the property include the Cabana Club, waterfront parks, pickleball and tennis courts, a playground, golf, restaurants, and walking paths. The backyard provides outdoor space, while the location places the residence near the recreational and service amenities of Key Colony Beach.
Key Highlights
- 1,031 square feet with 2 bedrooms and 2 bathrooms
- Elevated half duplex built in 1982
- Updated kitchen with granite countertops
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
$17,272
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
2.91%
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%
$345,440
$345.4K
Cap Rate 7%
$246,743
$246.7K
Cap Rate 9%
$191,911
$191.9K
Market Conditions
NOI Build-Up for 1,031 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
$26.4K $25.56/SF
− Vacancy
−$1.7K −$1.63/SF
EGI
$24.7K $23.93/SF
− OpEx
−$7.4K −$7.18/SF
NOI
$17.3K $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%
$345,440
Cap Rate 7%
$246,743
Cap Rate 9%
$191,911
Alternative Uses
Best Use
Multifamily LT 5
$246.7K
$215.9K – $287.9K
NOI $17,272 @ 7.0% cap · market cap 2.91%
Second Best
Apartment 5plus
$228.6K
$200.0K – $266.7K
NOI $15,999 @ 7.0% cap · market cap 2.69%
Theoretical Best
Office A
$414.7K
$362.9K – $483.8K
NOI $29,030 @ 7.0% cap · market cap 4.89%
Zoning and permitted uses should be independently verified with authorities.
Property Analytics
Property Profile
Current Use
Lease Details
1
Residential units
Location Intelligence
Trade Area within ½ mile
278
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 - Elevated two-bedroom half duplex with two bathrooms, a granite-finished kitchen, private balcony, and flexible lower-level living area.
Where is this duplex located?
The property is located at 310 3rd Street Key Colony Beach, FL.
What is the asking price?
The asking price for this property is $594,000.
What are key features of this property?
This property features: 1,031 square feet with 2 bedrooms and 2 bathrooms; Elevated half duplex built in 1982; Updated kitchen with granite countertops
