13 Riverside Ave · Mastic Beach, NY 11951

$549,000

3 bd · 3.0 ba · 2,340 sqft · SingleFamily public records · 137 Days on market

Built 1972 0.25 ac lot $235/sqft · 15% below area Est $648k · 15% under

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Why this score? — see what drove the D grade

The composite is a weighted blend of 9 inputs, each scored 0–100. Each bar is that input's sub-score; the figure is the points it added to the 100-point composite (weight × sub-score).

• ARV discount +14.4/15.0
• Appreciation +10.0/10.0
• Cash flow +4.8/30.0
• Schools +4.7/10.0
• Livability +3.1/5.0
• Rent growth +2.5/5.0
• Condition / age +2.5/5.0
• 1% rule +1.4/10.0
• DSCR +0.0/10.0

Listing remarks MLS

Waterfront living with endless potential on Poospatuck Creek, offering direct access to the Forge River and beyond. This split-level home is all about location, views, and opportunity. The upper level features an open floor plan designed to capture the water from every angle, with three sliding glass doors that open to a sprawling upper deck, perfect for entertaining, relaxing, and soaking in the scenery. Enjoy 100 feet of bulkhead and your own private dock, ideal for boating, kayaking, paddle boarding, or simply enjoying life on the water. Wake up to stunning sunrises and wind down with peaceful sunsets reflected across the creek. This setting delivers true waterfront serenity. The home offers two additional rooms with flexible use, ideal for a home office, gym, game room, or creative space. Buyers may also choose to add wardrobes to use these rooms as additional sleeping areas. The lower level includes exterior entrances, creating excellent potential for a guest suite or accessory apartment with proper permits. Whether you envision multigenerational living, rental income, or flexible work-from-home space, the layout supports a variety of possibilities This home offers a fantastic opportunity for buyers ready to bring their vision and create a custom waterfront retreat tailored to their style. With an unbeatable waterfront setting, this is a rare chance to own property with direct access to the Forge River and the Great South Bay.

Key facts

• 100 feet of bulkhead
• Private dock
• Waterfront living

Tags

• WATERFRONT LIVING
• SPRAWLING UPPER DECK
• PRIVATE DOCK
• 100 FEET OF BULKHEAD
• FLEXIBLE USE ROOMS
• EXTERIOR ENTRANCES

What this means for you Summary

Snapshot

• This is a 3-bed/3.0-bath single-family listed at $549k.

Deal economics

• At list price, monthly cash flow is $-2k ($-22k/yr) — negative.
• To cash-flow at today's rent, offer at most $240k (56.3% below list).
• To meet the 1% rule (rent ≥ 1% of price), the offer needs to be $350k (36.2% below list).
• Recommended offer: $240k (56.3% below list) — sets the bar for cash-flow.
• Cap rate 3.4% vs local median 4.7% in Mastic Beach — below-typical yield; the buyer is paying a premium for something (appreciation thesis, condition, location) that the cap rate doesn't capture.

Location & tenants

• Location reads 61/100 on livability (#936 in NY) — a middle-class / working-renter tenant base. Strengths: employment A+, housing A+; Watch: schools D, crime D, amenities F.
• William Floyd Union Free School District (suburban): math 48% / reading 57% proficiency, ranked #309 of 590 in NY (top 52%) — acceptable for families but not a draw, mixed tenant base, ~2y average lease.
• Market conditions: 133 active listings in the ZIP; 1 comparable units currently listed for rent nearby; 1,366 units permitted in Suffolk County in 2024 (216 in 5+ unit buildings).

Forward outlook

• In year one you build about $59k of equity ($4k loan paydown + $55k appreciation (10.0% local appreciation)).
• Suffolk County population projected to shrink 5% by 2050 — rents likely to lag national; underwrite the cash flow, not the appreciation.
• By year 2, paydown + projected appreciation supports a ~$94k cash-out refi (75% LTV) — recoverable capital for the next deal without selling this one.

Negotiation context

• It's been on market 137 days — a 12% lower offer ($483k) is reasonable based on typical stale-listing flexibility.
• 9 sale attempts since 14y ago with the ask held roughly flat each time — persistent listings suggest the price (not the market) is what's stuck; bring a comps-based counter.

Risks & watch-outs

• Watch-outs: flood insurance adds $460/mo.
• Climate carrying-cost: in FEMA flood zone AE (mandatory federal flood insurance); severe wind risk, 80% chance of damaging wind over 30y — expect insurance premiums to compound above CPI over the hold.

Recommended offer $240,038 (56.3% below list)

Questions for the listing agent

1. What do current leases actually rent for vs. the listed asking? Can we see a recent rent roll and the last 12 months of T-12 income?
2. It's been on market 137 days. Have you received any prior offers? Is the seller open to a 56% concession, seller financing, or rate buy-down credit?
3. Built in 1972 — when were the roof, HVAC, electrical panel, plumbing, and water heater last replaced?
4. What's the actual annual flood-insurance premium (NFIP or private), and is the property in a SFHA with mandatory coverage?
5. Why hasn't it sold? Are there any deal-killer items the seller is aware of (foundation, flood, title, zoning, code violations)?
6. Is there a deadline driving the sale (1031 exchange, divorce, estate, relocation)? That informs how much negotiation room exists.
7. Schools are D-rated, which usually means shorter tenancies and higher turnover. Who's the typical renter profile here, and what's been the actual vacancy rate?
8. Crime grade is D in this area — have there been break-ins, vandalism, or insurance claims at this property in the last 3 years? What carrier currently insures it and at what premium?
9. The area grade is low — what's the realistic commute time and amenity access for the typical tenant pool here? Any planned neighborhood developments (good or bad) we should know about?
10. What's the average days-on-market for RENTAL listings here right now (not sales)? A rising rental-DOM trend means longer vacancies and softer asking-rent achievability than the comps imply.
11. What's the recent tenant-quality profile in this submarket — average credit score on applications, eviction rate, late-payment / NSF rate, and stable-employment percentage? A property-management company in the area should have these aggregated.
12. How much new for-sale + rental construction is in the pipeline within 1–3 miles? Heavy new supply typically softens prices + rents 12–24 months out; constrained supply supports both.

Investment metrics

• 1% rule: 0.64% ✗
• Cap rate: 3.36%
• Cash-on-cash: -10.48%
• DSCR: 0.53
• GRM: 13.1

CMA / ARV

• ARV (median comp): $648,095
• List price: $549,000
• Delta: -15.29%
• Verdict: UNDERPRICED
• Comps: 20 within 1.0 mi

Show comp detail 5 sales within ~0.75 mi

Address	Dist	Beds/Ba	Sqft	Sold	Price	$/sf	Match
59 Riverside Ave	0.22mi	3/2.0	2,224 (-5%)	6mo	$529,000	$238	73
8 Estate Dr	0.40mi	3/2.5	2,300 (-2%)	22mo	$710,000	$309	58
20 Clover St	0.53mi	4/2.5 (+1)	2,537 (+8%)	11mo	$595,000	$235	45
31 Neptune Ave	0.63mi	4/4.0 (+1)	2,500 (+7%)	9mo	$630,000	$252	43
26 Coventry Ave	0.66mi	4/3.0 (+1)	2,000 (-14%)	8mo	$670,000	$335	33

Match score weights: distance 35% · size 25% · config 20% · recency 20%. Top-matched comps best support the ARV.

Projected returns pro-forma

10.0% appreciation · 3.0% rent growth · sell at horizon

5-year hold

• IRR: 14.5%
• Equity multiple: 2.20×
• Total profit: $184,673
• Equity at exit: $494,583

10-year hold

• IRR: 14.4%
• Equity multiple: 5.13×
• Total profit: $635,204
• Equity at exit: $1,066,586

Cash invested: $153,720 (down + closing). Projections, not guarantees.

Landlord ↔ Tenant lean methodology

• Overall (STATE): 15 Strongly Tenant-Friendly
• State New York: 15 Strongly Tenant-Friendly · D+10
• County: — inherits STATE
• City: — inherits STATE

NYC rent stabilization (~1M units); 2019 HSTPA strengthened tenant rights; courts deeply backlogged.

Methodology + full state rankings →

ZIP-level market 11951

• Home prices YoY: 4.3%
• Active inventory: 133
• Price-to-rent: 13.1×

Monthly cashflow live

• Estimated rent: $3,500 medium
• Mortgage (P&I): −$2,879
• Tax from tax record: −$1,000 /mo · $12,002/yr
• Insurance: −$229
• Flood insurance flood zone: −$460 /mo · $5,525/yr
• HOA: −$0
• Vacancy / Maint / Mgmt: −$735
• Net cashflow: $-1,803

Break-even live

Break-even rent $5,783

Max offer price $240,038

Occupancy floor —

Sensitivity live

Price	-10% $-1,493	-5% $-1,648	+0% $-1,803	+5% $-1,959	+10% $-2,114
Rent	-10% $-2,080	-5% $-1,942	+0% $-1,803	+5% $-1,665	+10% $-1,527
Rate	-1.0pp $-1,527	-0.5pp $-1,664	base $-1,803	+0.5pp $-1,946	+1.0pp $-2,090

UW: 25.0% down · 7.5% · 30yr · 1.5% tax · 5.0% vac · 8.0% maint · 8.0% mgmt

Financing live

Cash to close

• Down payment: $137,250
• Closing costs: $16,470
• Reserves months: —
• Total cash needed: —

Rent comps 1 comps

Address	Beds	Baths	Sqft	Rent	$/sqft	DOM	Units	Dist
367 Seabreeze Ct Moriches, NY	2.0	2.0	2141	$3,500	$1.63	1d	1	1.00mi

Listing history 35 events

1. 2026-06-13
   days on market $549,000 Active 137 DOM
2. 2026-06-13
   days on market $549,000 Active 136 DOM
3. 2026-06-09
   days on market $549,000 Active 133 DOM
4. 2026-06-08
   days on market $549,000 Active 132 DOM
5. 2026-06-07
   days on market $549,000 Active 131 DOM
6. 2026-06-04
   days on market $549,000 Active 128 DOM
7. 2026-06-03
   days on market $549,000 Active 127 DOM
8. 2026-06-02
   days on market $549,000 Active 126 DOM
9. 2026-06-01
   days on market $549,000 Active 125 DOM
10. 2026-05-31
    days on market $549,000 Active 124 DOM
11. 2026-01-23
    listed $549,000 Active 1461-char remark

    Show marketing remark (1461 chars)

    Waterfront living with endless potential on Poospatuck Creek, offering direct access to the Forge River and beyond. This split-level home is all about location, views, and opportunity. The upper level features an open floor plan designed to capture the water from every angle, with three sliding glass doors that open to a sprawling upper deck, perfect for entertaining, relaxing, and soaking in the scenery. Enjoy 100 feet of bulkhead and your own private dock, ideal for boating, kayaking, paddle boarding, or simply enjoying life on the water. Wake up to stunning sunrises and wind down with peaceful sunsets reflected across the creek. This setting delivers true waterfront serenity. The home offers two additional rooms with flexible use, ideal for a home office, gym, game room, or creative space. Buyers may also choose to add wardrobes to use these rooms as additional sleeping areas. The lower level includes exterior entrances, creating excellent potential for a guest suite or accessory apartment with proper permits. Whether you envision multigenerational living, rental income, or flexible work-from-home space, the layout supports a variety of possibilities This home offers a fantastic opportunity for buyers ready to bring their vision and create a custom waterfront retreat tailored to their style. With an unbeatable waterfront setting, this is a rare chance to own property with direct access to the Forge River and the Great South Bay.

12. 2025-01-20
    historical
13. 2024-11-28
    price $689,000
14. 2024-11-05
    listed $689,000 Active
15. 2021-10-12
    soldstatus $530,000
16. 2015-09-28
    soldstatus $210,000
17. 2015-09-04
    soldstatus $210,000
18. 2015-09-04
    soldstatus $210,000 Closed
19. 2015-09-02
    status Under Contract
20. 2015-08-12
    price $230,000
21. 2015-08-12
    price $239,000
22. 2015-05-16
    listed $255,000 New
23. 2015-05-16
    listed $230,000
24. 2015-05-15
    historical
25. 2015-03-07
    listed $259,000
26. 2014-12-30
    historical
27. 2014-09-08
    listed $295,000
28. 2013-11-01
    historical
29. 2013-09-05
    listed $379,000
30. 2013-08-28
    historical
31. 2013-04-08
    listed $392,000
32. 2012-10-31
    historical
33. 2012-03-31
    listed $425,000
34. 2008-08-15
    soldstatus $81,250
35. 1988-11-02
    soldstatus $184,500

ⓘ Source: listings_history table (triggers on properties + properties_extension) + one-shot backfill from property_details.listing_events for pre-trigger history.

Tax reassessment forecast NY · Partial reset (capped growth)

• Current annual tax: $12,002 · $1,000/mo
• Projected year-2 tax: $12,002 · $1,000/mo
• Expected delta: $0/yr ($0/mo · 0.0%)

ⓘ Screening estimate from a state-policy table — verify with the county assessor before closing.

Climate risk First Street

• 🌊 Flood 7/10 Severe FEMA zone AE · 96% chance over 30 yrs
• 🔥 Wildfire 3/10 Moderate
• 🌡 Heat 4/10 Moderate 7 d/yr ≥91°F today · 19 d/yr by 30 yrs out
• 💨 Wind 8/10 Severe 80% chance of damaging wind over 30 yrs
• 🫁 Air quality 4/10 Moderate 3 unhealthy d/yr today · 5 by 30 yrs out

Taxation est. · year 1

• Rental income: $42,000
• − Mortgage interest: −$30,753
• − Property taxes: −$12,002
• − Insurance: −$8,270
• − Repairs & maintenance: −$3,360
• − Management: −$3,360
• − Depreciation: −$15,971
• Taxable loss: −$31,715
• Est. tax savings @ 24.0%: +$7,612
• After-tax cash flow: $-14,028/yr

For passive investors: Depreciation is non-cash, so a rental often shows a tax loss while cash-flowing — sheltering income. Rental losses are passive: they offset passive income freely, and up to $25,000/yr can offset ordinary (W-2) income if you actively participate and your MAGI is under $100k (phasing out to $0 by $150k); unused losses carry forward. On sale, claimed depreciation is recaptured at up to 25%, and gains may owe capital-gains tax (a 1031 exchange can defer both). Figures are a year-1 estimate at your 24.0% rate — not tax advice; consult a CPA.

Schools (NCES district)

• District: William Floyd Union Free School District
• NCES district ID: 3618690
• Math proficiency: 48% ▲ 3.00%
• Reading proficiency: 57% ▲ 11.00%
• Median HH income: $70,564
• Composite: 46.79/100
• National rank: #2383
• State rank: #309 of 590 in NY

Livability — Mastic Beach

• Score: 61/100
• State rank: #936
• US rank: #18216

Category grades

Amenities F Commute F Cost of living F Crime D Employment A+ Housing A+ Health & safety F User ratings C

Schools grade is shown separately in the Schools card above.

Census & demographics

• Census place: Mastic Beach, NY
• City population: 15,830
• Population (ZIP): 15,830

Population outlook (Suffolk County) Hauer SSP2

• Today (2025): 1,505,262 people
• By 2030: 1,498,318 · -0.5%
• By 2040: 1,471,101 · -2.3%
• By 2050: 1,424,848 · -5.3%
• By 2075: 1,337,157 · -11.2%
• By 2100: 1,217,720 · -19.1%

Race, ethnicity, and origin ACS 2023

• Neighborhood character: Predominantly White (68%)
• Race & ethnicity: White 68% Hispanic / Latino 17% Two or more races 9% Black 6% Asian 2%
• Hispanic origin (detail): Mexican 1% Puerto Rican 6% Cuban 2%
• Common ancestry: Lithuanian 3% Romanian 2% Italian 2%
• Foreign-born: 7% · Canada, Vietnam
• Languages at home: 84% English-only · Spanish 10% Other Indo-European 3% Chinese 1%

Political lean MEDSL · Suffolk

• 2024 margin: Lean R (+10.0) · D 45.0% · R 55.0%
• 2008→2024 swing: -16.0pp toward R · 2008: 6.0pp · 2024: -10.0pp
• All cycles: 2024: R+10.0 2020: R+0.0 2016: R+8.2 2012: D+2.9 2008: D+6.0

Not yet ingested

• Civics: —

Market trends

• HPI YoY: ▲ 34.46%
• Current HPI: 829.86
• Rent YoY: —
• Metro: —
• State GDP YoY: ▲ 2.60%
• F500 in state: 92

Industry mix (Fortune 500 HQ in NY)

Industry	F500 HQs	Revenue
▸Financial Services	10	$950B
▸Consumer Goods	9	$162B
▸Insurance	4	$225B
▸Telecommunications	2	$144B
▸Pharmaceuticals	2	$112B
▸Media / Entertainment	2	$69B

Price history

+197.6% since first listed

25 events — show timeline

• 2026-01-23 Listed $549,000 OneKey® MLS as Distributed by MLS Grid
• 2025-01-20 Listing Removed — OneKey® MLS as Distributed by MLS Grid
• 2024-11-28 Price Changed $689,000 OneKey® MLS as Distributed by MLS Grid
• 2024-11-05 Listed $689,000 OneKey® MLS as Distributed by MLS Grid
• 2021-10-12 Sold (Public Records) $530,000 Public Records
• 2015-09-28 Sold (Public Records) $210,000 Public Records
• 2015-09-04 Sold (MLS) $210,000 MLSLI
• 2015-09-04 Sold (MLS) $210,000 OneKey® MLS as Distributed by MLS Grid
• 2015-09-02 Pending — MLSLI
• 2015-08-12 Price Changed $230,000 MLSLI
• 2015-08-12 Price Changed $239,000 MLSLI
• 2015-05-16 Listed $255,000 MLSLI
• 2015-05-16 Listed $230,000 OneKey® MLS as Distributed by MLS Grid
• 2015-05-15 Listing Removed — OneKey® MLS as Distributed by MLS Grid
• 2015-03-07 Listed $259,000 OneKey® MLS as Distributed by MLS Grid
• 2014-12-30 Listing Removed — OneKey® MLS as Distributed by MLS Grid
• 2014-09-08 Listed $295,000 OneKey® MLS as Distributed by MLS Grid
• 2013-11-01 Listing Removed — OneKey® MLS as Distributed by MLS Grid
• 2013-09-05 Listed $379,000 OneKey® MLS as Distributed by MLS Grid
• 2013-08-28 Listing Removed — OneKey® MLS as Distributed by MLS Grid
• 2013-04-08 Listed $392,000 OneKey® MLS as Distributed by MLS Grid
• 2012-10-31 Listing Removed — OneKey® MLS as Distributed by MLS Grid
• 2012-03-31 Listed $425,000 OneKey® MLS as Distributed by MLS Grid
• 2008-08-15 Sold (Public Records) $81,250 Public Records
• 1988-11-02 Sold (Public Records) $184,500 Public Records

Property tax history

+3.5%/yr

Latest (2025): $12,002 · +0.0% YoY. Source: county tax records.