Boulder County property record for 345 S 42nd St, Boulder, CO 80305
| Property Type | Single Family Home |
|---|---|
| Details | 4 bd · 2.75 ba · 2,100 sqft · built 1956 |
| Lot Size | 0.173 acres (7,535 sqft) |
| Owner | 2 Individual Names on File |
| Last Sale | $890,000 (May 2025) |
| Tax Bill | $4,757 (2025) |
| Flood Zone | Zone X (minimal risk) |
| APN | 1577-05-4-24-029 |
| Primary APN | 1577-05-4-24-029 |
|---|---|
| Alternative APNs |
|
| Bedrooms | 4 Beds |
|---|---|
| Full Baths | 2.75 Baths |
| Half Baths | 1 Half Bath |
| Total Rooms | 5 Rooms |
| Stories | 1 Story |
| Building Area | 2,100 sqft Living Area |
| Gross Area | 2,500 sqft |
| 1st Floor Area | 1,150 sqft |
| Basement Area | 1,150 sqft |
| Interior Walls | Wallboard/Drywall |
| Year Built | Built 1956 |
|---|---|
| Effective Year Built | Effective 1988 |
| Architectural Style | Ranch |
| Exterior Material | Brick Veneer |
| Construction Type | Masonry / Concrete Block |
| Lot Area | 7,535 sqft (0.173 acres) |
| Garage Type | Attached |
| Garage Area | 200 sqft |
| Parking Spaces | 1 Parking Space |
| Porch | Slab |
| Porch Area | 240 sqft |
| Cooling System | Central |
|---|---|
| Heating System | Forced Air with A/C |
| Account Number | R0012316 |
|---|---|
| Street Address | 345 S 42ND ST |
| City | BOULDER |
| State | CO |
| Zip | 80305-5453 |
| Property Category | Residential |
| Property Type | Residential > Single Family > Home |
| Legal Description | LOT 29 BLK 7 MARTIN ACRES 2 |
| Legal Range | 70 |
| Legal Township | 1S |
| Legal Section | 05 |
| Legal Subdivision | MARTIN ACRES 2 - BO |
| Legal Block | 7 |
| Legal Lot Number | 29 |
| Jurisdiction | BOULDER CO |
| Township / Civil Division | BOULDER |
| Census Block Group | 3 |
| Census Block | 3008 |
| Census Tract | 12507 |
345 S 42nd St is owned and occupied by two individuals who bought it in May 2025.
Source: Boulder County records, as of October 16, 2026
| Owner of Record | 2 Individual Names on File |
|---|---|
| Mailing Address | 345 S 42ND ST, BOULDER, CO 80305-5453 |
| Occupancy | Owner Occupied |
| Owner Type | Individual |
| Vesting | Joint Tenants |
Owner names and exact recorded amounts are on file and can be viewed instantly on this page with a free 10-day trial.
| Deed Names | 2 Names on Deed |
|---|---|
| Last Sale | May 21, 2025 · Amount on File |
| Deed Sale | May 21, 2025 · Amount on File |
| Prior Sale | Jun 30, 1998 · Amount on File |
| Deed Document Number | 20254088390 |
| Prior Transfer Date | Apr 28, 2004 |
| Prior Transfer Doc | 0002587783 |
| Record Updated | Oct 29, 2026 |
The 2025 property tax bill for 345 S 42nd St was $4,757.
Source: Boulder County assessment roll, as of September 18, 2026
| Type | Name |
|---|---|
| State | Colorado |
| County | Boulder County |
| Municipality | Boulder City |
| Unified School District | Boulder Valley School District RE-2 (PK - 12) |
| Year | Tax Bill | Assessed Value | Assessed Market Value |
|---|---|---|---|
| 2026 | $59,099 (+18.43%) Land $34,184 Building $24,915 | $939,100 (+17.62%) Land $572,700 Building $366,400 | |
| 2025 | $4,757.00 | $49,900 Land $35,794 Building $14,106 | $798,400 Land $572,700 Building $225,700 |
| 2023 | $4,599.00 (+8.42%) | $56,943 (+24.65%) Land $41,942 Building $15,001 | $849,900 (+29.3%) Land $626,000 Building $223,900 |
| 2022 | $4,242.00 | $45,682 Land $31,108 Building $14,574 | $657,300 Land $447,600 Building $209,700 |
Assessed value and assessed market value are set for property tax purposes, not market price estimates; both are a fraction of this property's market value.
FEMA maps place 345 S 42nd St in Zone X, an area of minimal flood risk, though there have been 7 flood claims nearby since 1979.
Source: FEMA National Flood Hazard Layer, effective October 14, 2026 · OpenFEMA NFIP redacted claims and policies, as of September 2026
| FEMA Flood Zone | Zone X minimal risk |
|---|---|
| Flood Insurance Requirement | Not required lenders may require it |
| Community Rating System | Class 5 (25% premium discount) |
| Nearby Flood Policies | 6 in force |
| Nearby Flood Claims | 7 (1979–2022) |
| Claims Outside the SFHA | 5 of 7 |
| Most Recent Claim | Jul 2022 · rainfall accumulation |
| Claims by Event |
|
Values are read at the parcel center point; flood claims are located to the census block group, not this parcel; lenders make the official flood determination.
Wildfire risk around 345 S 42nd St is low, with a 0.01% annual chance of wildfire.
Source: USDA Forest Service Wildfire Risk to Communities (2nd edition), as of 2024
| Wildfire Risk | Low lower than 80% of the US · lower than 91% of Colorado |
|---|---|
| Wildfire Likelihood | 0.01% annual chance |
| Exposure | None beyond ember reach |
Values cover an area roughly 900 ft across, not the parcel itself; insurers use their own ratings.
Source: EPA Safe Drinking Water Information System, as of September 2026
| Water System | CITY OF BOULDER serves 166,080 people · EPA ID CO0107152 |
|---|---|
| Water Source | Surface water |
| Last State Inspection | Sep 2024 |
| Lead | 2 ppb (2023–2025) action level 15 ppb |
| Water Quality | Haloacetic acids resolved · Jul 2017 |
|---|---|
| Treatment and Procedure | None last 10 years |
| Monitoring and Reporting | 1 last 3 years |
Results are for the whole water system, not water tested at this address; lead at the tap also depends on the building's own pipes.
Source: FCC Broadband Data Collection, based on 678 locations within half a mile, as of December 31, 2025
| Provider | Max Down / Up (Mbps) |
|---|---|
| Ayva Networks Fixed Wireless | 2,500 / 2,500 |
| CenturyLink Fiber · DSL in parts of the area | 2,000 / 1,000 |
| Xfinity Cable | 2,000 / 250 |
| Verizon Fixed Wireless | 300 / 20 |
| LiveWireNet Fixed Wireless | 250 / 100 |
| T-Mobile Fixed Wireless | 100 / 20 |
May also be available: AT&T.
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