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1718 Rockspring Place

Joaquin Ranch · Walnut Creek

1718 Rockspring Place

Style

Single Family Residence

Zoning

PD

Year built

1982

Existing

5 bd · 4 ba

Interior

3,105 sf

Lot size

18,184 sf

$2,400,000

Unlisted

Development Scenarios

Here's how you can use existing housing laws to add more housing units to this property. For illustrative purposes only, as actual site conditions should be verified in person.

ADU

Add 1 potential unit to the backyard
$272K-$502K estimated cost
$345K-$863K future value add
Loading infill model...

Density level

Density controls will appear after the model finishes loading.

Generating the lot configuration for this scenario and density...

Financials

These estimates model the potential development economics for this scenario using local construction costs and comparable sale prices. They're provided for illustrative purposes only and aren't financial advice.

Selected ScenarioADU
Estimated Project Cost
$2,743,802
ADU scenario · 1 new unit · 400 new sf
Build Cost / SF
$
ADU build cost$271,802
10% of project cost
Property acquisition$2,472,000
90% of project cost
Estimated Project Value (2 Year)
$2,745,200
0.1% total ROI
$1,398 potential ROI
Added scenario value$345,200
13% of completed value
Current property value$2,400,000
87% of completed value
Acquisition90%
Soft Costs2%
Hard Costs8%
Value Projections
Today estimate$2,400,000
Scenario added sqft$345,200
Completed value$2,745,200
Potential ROI$1,398
Assumptions
Current value / sf$863
Added sqft400 sf
Cost Breakdown

Unit Economics
Original Property
Acquisition only
Build New Homes
Soft + hard costs
All-In
Total project
# of original homes
N/A
# of new homes
1
Total homes
1
Per Home
N/A
Per Home
$272K
Per Home
$2.74M
# of original sq ft
2,781
# of new sq ft
400
Total sq ft
3,181
Per Sq Ft
N/A
Per Sq Ft
$680
Per Sq Ft
$863
Total
$2.47M
Total
$272K
Total
$2.74M
Financing Estimate
HELOC

Estimate available equity and interest-only payments for funding the build.

HELOC Estimate
Available Equity
Estimated current value
Internal current-value baseline
$2.40M
Max HELOC
80% CLTV minus mortgage balance
$480K
Requested HELOC
Capped by available equity
$272K
Monthly payment
Interest-only estimate
$1K

Timeline

Typical project phasing based on the selected scenario, density, and generated development scope.

Estimated Total Duration

11 months

ADU

Design

Concept design, site planning, and early coordination.

1 month

Month 1

Permitting

Planning review, entitlement approvals, and building permits.

3 months

Month 2 - Month 4

Site Work

Utility coordination, grading, and site preparation.

2 months

Month 5 - Month 6

Construction

Vertical construction through final inspection.

5 months

Month 7 - Month 11

Property Overview

MLS: bridgeMLS

Property information from bridgeMLS

Listed by Lori Legler · Dudum Real Estate Group

bridgeMLS © 2026. Information Deemed Reliable but not Guaranteed. This information is being provided by bridgeMLS. The listings presented here may or may not be listed by the Broker/Agent operating this website. This information is intended for the personal use of consumers and may not be used for any purpose other than to identify prospective properties consumers may be interested in purchasing. Data last updated at September 4, 2026 at 12:12 AM PDT.

Location

Data from Type Five
Jurisdiction
Walnut Creek
Zoning
PD
Overlay Districts
None
Climate Zone
Zone 12
Transit Access (1/2 mi)
No

Natural Hazards

Data from Type Five
Flood Zone
X
Liquefaction Risk
Yes
Landslide Risk
No
Fault Zone
No

Fire Risk

Data from Type Five
Fire Hazard Zone
NOT IN A VHFHZ
Fire Responsibility
LRA
Wildfire Protection Req.
-
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