3421 4th St, Boulder, CO 80304
FOR SALE
OPEN SAT, 12-4PM
0.6 ACRES

3421 4th St
Boulder, CO 80304

Juniper - Kalmia
  • 6 Beds
  • 4.5 Baths
  • 5,198 sqft (on 0.60 acres)

$6,800,000

Est. Mortgage $36,892/mo*
Get Pre-Qualified

$6,800,000

Est. Mortgage $36,892/mo*
Get Pre-Qualified
6 Beds
4.5 Baths
5,198 sqft
(on 0.60 acres)

Local Information

Map showing home location
© Google
-- mins to
Commute Destination

Description

Newlands Sanctuary on Mt. Sanitas Open Space Step onto the 600-square-foot deck and look up. Mt. Sanitas rises 1,300 feet from your backyard gate, private access to the Goat Trail. No driving. No parking. Just you, your coffee, and maybe a 4-legged friend who will make sure you don't skip it. This premier property is one of eight homes backing directly to open space. In 21 years, only one has changed hands. Hidden behind a 70-yard tree-lined driveway on a 0.6-acre lot (2.5x standard), this is widely regarded as one of Boulder's best addresses, served by top rated schools.The 5,200-square-foot residence features 20-foot ceilings with west-facing glass framing Mt. Sanitas, white oak floors, two fireplaces, and a library overlooking the property's seven heritage apple trees. Six bedrooms plus office (convertible seventh) include three distinct suites: the primary en-suite with a stunning view; a garden-level walkout in-law addition (2005, 12' ceilings) with separate entrance, private patio, and dedicated office-ideal for multigenerational living or guests-plus a basement suite with whirlpool bath. Outside you will discover a deep wrap-around porch beneath a 60-foot silver maple, flower and vegetable gardens, and the historic Silver Lake Ditch with 12,000 gallons daily water rights. Sundance Film Festival arrives January 2027, venues minutes away providing a chance at an incredible rental income opportunity and under the Augusta Rule, 14 days of rental income may be tax-free. Roof replaced 2019. New carpet. Heated two-car garage. No HOA. No covenants. For those who know Newlands: this is the privacy, the lot, the view, and the trail access that almost never comes to market. For those discovering Boulder for the first time: welcome to the neighborhood the locals covet most.

Open House

Saturday, June 20
12:00 PM to 4:00 PM
Sunday, June 21
12:00 PM to 4:00 PM
Saturday, June 27
12:00 PM to 4:00 PM
Sunday, June 28
12:00 PM to 4:00 PM
Sunday, July 05
12:00 PM to 4:00 PM
Sunday, July 12
12:00 PM to 4:00 PM
Sunday, July 19
12:00 PM to 4:00 PM
Sunday, July 26
12:00 PM to 4:00 PM
Sunday, August 02
12:00 PM to 4:00 PM
Sunday, August 09
12:00 PM to 4:00 PM
Sunday, August 16
12:00 PM to 4:00 PM
Sunday, August 23
12:00 PM to 4:00 PM
Sunday, August 30
12:00 PM to 4:00 PM

Home Highlights

Parking
2 Car Garage
Outdoor
Patio, Deck
A/C
Heating & Cooling
HOA
None
Price/Sqft
$1,308
Listed
95 days ago

Home Details for 3421 4th St

Interior Features

Interior Details
Basement: Full,Partially Finished,DaylightNumber of Rooms: 13Types of Rooms: Primary Bedroom, Bedroom 2, Bedroom 3, Bedroom 4, Bedroom 5, Bedroom 6, Dining Room, Great Room, Kitchen, Laundry, Living Room, Recreation Room, Study
Beds & Baths
Number of Bedrooms: 6Number of Bathrooms: 5Number of Bathrooms (full): 2Number of Bathrooms (three quarters): 2Number of Bathrooms (half): 1Number of Bathrooms (main level): 2
Dimensions and Layout
Living Area: 5198 Square Feet
Appliances & Utilities
Utilities: Natural Gas Available, Electricity Available, Cable Available, High Speed AvailAppliances: Gas Range, Down Draft, Self Cleaning Oven, Dishwasher, Refrigerator, Microwave, DisposalDishwasherDisposalMicrowaveRefrigerator
Heating & Cooling
Heating: Forced Air,Hot Water,Zoned,Radiant,2 or more Heat SourcesHas CoolingAir Conditioning: Evaporative Cooling,Ceiling Fan(s)Has HeatingHeating Fuel: Forced Air
Fireplace & Spa
Fireplace: Two or More, Gas, Gas Log, Living Room, Family RoomSpa: BathHas a Fireplace
Gas & Electric
Electric: XcelGas: XcelHas Electric on Property
Levels, Entrance, & Accessibility
Stories: 4Levels: Four
View
Has a ViewView: Hills
Security
Security: Fire Alarm

Exterior Features

Exterior Home Features
Roof: CompositionPatio / Porch: Patio, DeckFencing: Partial, Fenced, Wood, Chain LinkExterior: Sprinkler SystemSprinkler System
Parking & Garage
Number of Garage Spaces: 2Number of Covered Spaces: 2Other Parking: AttachedNo CarportHas a GarageHas an Attached GarageParking Spaces: 2Parking: Garage Door Opener,Attached,Oversized
Frontage
Road Frontage: City StreetRoad Surface Type: AsphaltNot on Waterfront
Water & Sewer
Sewer: Public Sewer
Farm & Range
Does Not Include Irrigation Water Rights
Finished Area
Finished Area (above surface): 3927 Square FeetFinished Area (below surface): 1271 Square Feet

Days on Market

Days on Market: 95

Property Information

Year Built
Year Built: 1990
Property Type / Style
Property Type: ResidentialProperty Subtype: Single Family ResidenceArchitecture: Legal Conforming,Contemporary
Building
Construction Materials: Frame, Wood SidingNot a New ConstructionNot Attached Property
Property Information
Usage of Home: Single FamilyNot Included in Sale: Furnishings and Personal PropertyParcel Number: R0108936

Price & Status

Price
List Price: $6,800,000Price Per Sqft: $1,308

Active Status

MLS Status: Active

Location

Direction & Address
City: BoulderCommunity: Fourth Street 3403 Sub
School Information
Elementary School: FoothillJr High / Middle School: CentennialHigh School: BoulderHigh School District: Boulder Valley Dist RE2

Agent Information

Listing Agent
Listing ID: 1053821

Building

Building Area
Building Area: 5198 Square Feet

HOA

No HOA

Lot Information

Lot Area: 0.60 acres

Listing Info

Special Conditions: Other Owner

Offer

Listing Terms: Cash, Conventional, 1031 Exchange

Miscellaneous

BasementMls Number: 1053821Attribution Contact: 970-531-7448Above Grade Unfinished Area: 3927Activation Date: Fri Mar 13 2026Showing Service Name: ShowingTime
Last check for updates: about 2 hours ago
Listing courtesy of Kathleen Haas, (970) 531-7448
Colorado Realty 4 Less, LLC
Source: IRES as distributed by MLS GRID, MLS#1053821
Also Listed on REcolorado as distributed by MLS GRID, REcolorado as distributed by MLS GRID, IRES as distributed by MLS GRID.

Market trends in Boulder

Last updated May 2026
Buyer'sMarketSeller'sMarket
Avg. sale price
$955K
$13.33KMoM
Sale-to-List Price
97.9%
1.0%MoM
Price per sq ft
$503
$12MoM
Available listings
775
41MoM

Price History for 3421 4th St

DatePriceEventSource
03/13/2026$6,800,000Listed For SaleREcolorado as distributed by MLS GRID #IR1053821
12/19/2025$7,250,000ListingRemovedIRES as distributed by MLS GRID #1037712
06/26/2025$7,250,000Listed For SaleIRES as distributed by MLS GRID #1037712
09/16/2004$1,750,000Sold
N/A

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Property Tax and Assessment

Year2025
Tax$26,869
Assessment$4,367,900
Home facts updated by county records

Comparable Sales for 3421 4th St

Address
Distance
Property Type
Sold Price
Sold Date
Bed
Bath
Sqft
503 Kalmia Ave, Boulder, CO
0.22
Single-Family Home
$3,438,500
05/26/26
4
3.5
5,381
3561 4th St, Boulder, CO
0.08
Single-Family Home
$2,050,000
03/06/26
4
3
3,879
700 Linden Ave, Boulder, CO
0.35
Single-Family Home
$3,700,000
08/01/25
4
3
5,244
865 Kalmia Ave, Boulder, CO
0.39
Single-Family Home
$2,950,000
04/29/26
5
3.5
4,220
503 Hawthorn Ave, Boulder, CO
0.19
Single-Family Home
$5,150,000
06/12/26
6
5.5
5,670
550 Iris Ave, Boulder, CO
0.19
Single-Family Home
$4,000,000
01/16/26
4
4
4,473
1107 Juniper Ave, Boulder, CO
0.46
Single-Family Home
$3,580,000
07/18/25
5
5.5
5,058
910 Kalmia Ave, Boulder, CO
0.43
Single-Family Home
$2,330,000
06/11/26
4
3.5
5,371
3119 9th St, Boulder, CO
0.54
Single-Family Home
$2,500,000
10/17/25
6
4.5
4,138

Nearby homes

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Assigned Schools

These are the assigned schools for 3421 4th St.
View nearby schools on GreatSchools
The GreatSchools Rating compares schools on a variety of school quality indicators including test scores, college readiness, equity and more. Learn more.

Neighborhood Overview

Juniper - Kalmia
See Local Highlights
Neighborhood stats provided by third party data sources.

What Locals Say about Juniper - Kalmia

At least 2 Trulia users voted on each feature.

  • 100 % Say parking is easy

  • 100 % Say there are community events

  • 100 % Say it's dog friendly

  • 100 % Say there's holiday spirit

  • 100 % Say people would walk alone at night

  • 100 % Say it's quiet

  • 100 % Say there's wildlife

  • 80 % Say it's walkable to grocery stores

  • 77 % Say neighbors are friendly

  • 75 % Say kids play outside

  • 71 % Say yards are well-kept

  • 67 % Say it's walkable to restaurants

  • 40 % Say there are sidewalks

  • 33 % Say streets are well-lit

Sourced by Trulia users. Learn more about our methodology.
  • Megan La Grave
    "Fantastic neighborhood for all ages and pets! Come walk it sometime and see for yourself. Close to the trails "
    0
    Flag
  • Trulia User
    "A close knit neighborhood and desirable area of Boulder at the foot of the mountains. You are as likely to get a wave as you are to see wildlife walking down the middle of the street."
    1
    Flag

LGBTQ Local Legal Protections

Kathleen Haas, Colorado Realty 4 Less, LLC
Agent Phone: (970) 531-7448
Based on information submitted to the MLS GRID as of 2026-06-17 12:47:58 PDT. All data is obtained from various sources and may not have been verified by broker or MLS GRID. Supplied Open House Information is subject to change without notice. All information should be independently reviewed and verified for accuracy. Properties may or may not be listed by the office/agent presenting the information. Some IDX listings have been excluded from this website. Click here for more information
3421 4th St, Boulder, CO 80304 is a 6 bedroom, 5 bathroom, 5,198 sqft single-family home built in 1990. 3421 4th St is located in Juniper - Kalmia, Boulder. This property is currently available for sale and was listed by IRES as distributed by MLS GRID on Mar 13, 2026. The MLS # for this home is MLS# 1053821.