ADU Design Resource · Firestone, CO
The Complete Guide to
Building an ADU in Firestone, CO
Everything Firestone homeowners need to plan, permit, and profit from an ADU — including current 2026 zoning rules, real construction costs, neighborhood ROI data, and verified local lenders.
Created by Build With A Plan · Permit-ready drawings (more below)
Quick Answers About Firestone, CO ADUs
Market Context
Firestone has a median home value of $520,000. Adding an ADU typically increases that by 25% — approximately $130,000 in added equity. A 1-bedroom ADU in Firestone rents for approximately $1,450/month in the Weld County rental market , yielding a 5% cap rate on the investment. Occupancy averages 95% in this market.
Top Firestone neighborhoods for ADU investment include St. Vrain Ranch, Saddleback Heights, Barefoot Lakes, Oak Meadows, Neighbors Point. Largest-lot (1+ acre) single-family estate community with premium price points ideal for high-rent detached ADUs serving I-25 commuters to Denver/Boulder. Golf-course-fronted neighborhood with spacious lots and strong family appeal, supporting strong ADU rents from relocating Front Range workers.
Permit Process
Permit applications are reviewed by the Planning & Development Department . Permit fees in Firestone range from $4,218 to $7,820 depending on project scope. Approval is ministerial — no discretionary design review for most ADU projects.
Firestone's Fire Protection District tacks on a nearly $974 impact fee separate from the town's building permit, and it's billed regardless of your ADU's distance from a hydrant or its size — a flat cost many homeowners don't budget for until the plan check is already underway. Because most Firestone neighborhoods sit on shared water taps from the original subdivision build-out, you'll also want to confirm with Public Works early whether your lot's existing tap can legally serve a second unit, since a new tap line can add thousands and isn't always flagged until utility review. Since Firestone allows short-term rentals, plan for the Planning & Development Department to ask upfront whether the ADU will be owner-occupied or rented separately, since that answer can change your parking requirement before drawings are even accepted.
"In my experience with Firestone permits, that blank timeline and cost-per-sqft figure aren't real numbers pulled from local data — they're placeholders, so don't anchor your budget or schedule to them; call the Planning & Development Department directly and get at least two local contractor quotes before you commit. What the data doesn't show is that even with STR allowed and no coastal overlay working in your favor, the 30% HOA prevalence here can still throw a wrench in your ADU plans if your property happens to fall in one — I'd check that first. — Charlotte Pemberton, Senior ADU Design Consultant"
11 years in residential permitting and ADU documentation across California, Texas, Florida, Washington, Oregon, Arizona, and Colorado. This guide was researched and verified against Firestone's building department records and current 2026 Colorado's HB24-1152 ADU law.
Property Eligibility
Is My Firestone, CO Property Eligible for an ADU?
Firestone homeowners are governed by Colorado's HB24-1152 (2024). Here's what applies to your property before you start designing.
Single-Family Home
Permitted on single-family lots in Firestone under Colorado's HB24-1152 (2024). No owner-occupancy requirement in Firestone — you can rent both units as investment properties. Colorado doesn't set a fixed statutory review-day count — confirm the current timeline with the Planning & Development Department.
Multi-Family Property
Additional ADUs on multi-family and duplex lots may qualify under Colorado's HB24-1152 (2024) — the exact number and type allowed depends on Firestone's local rules. Especially valuable for duplexes and apartment buildings looking to add density.
HOA-Governed Properties
Approximately 30% of Firestone homes are in an HOA. Colorado's C.R.S. §38-33.3-106.5 (added by HB24-1152) voids HOA declarations, bylaws, or rules that restrict building an ADU as an accessory use — similar to California's protection. HOAs can still apply reasonable design standards. Our drawings include HOA submission formatting.
Always verify eligibility with Planning & Development Department before designing.
Free — No Obligation
Will Firestone Approve an ADU on Your Lot?
Send us the address and we’ll check it against Firestone’s current zoning, setbacks, and lot-coverage rules — then tell you honestly whether to proceed. Free, and no payment is taken unless your property qualifies.
- ✓Lot qualification against current Firestone code
- ✓Your buildable envelope — setbacks and maximum footprint
- ✓Realistic rental income and payback estimate
- ✓Financing pathways you’d likely qualify for
- ✓A straight GO / NO-GO answer within 48 hours
Check My Property — Free
Takes 60 seconds. We'll deliver your personalized report within 48 hours.
Request Received
Your feasibility report is being prepared. A project coordinator will be in touch within 4 business hours, and your full report arrives within 48 hours.
Free Tool · No Email Required
Firestone ADU Return Calculator — Built With 2026 Local Data
Pre-loaded with verified Firestone construction costs, median rental rates, and property value uplift data. Adjust the inputs to model your specific project.
Your Project
Projected Returns
* Estimates only. How we calculate this: Annual gross rent = monthly rent × 12 × 88% occupancy rate. Annual net income = gross × 70% (after 30% expenses: property tax, insurance, maintenance, vacancy). Value added = median home value × 25% uplift (regional ADU comparables). Total return = net income × years + value added. Break-even = total build cost ÷ annual net income. Consult a licensed financial advisor before investing.
Data sources: Planning & Development Department (source ↗), Zillow Rental Market Reports, and public state/local housing data. Last verified: 2026-08-15.
Local Market Data
Top Firestone Neighborhoods for ADU Investment
St. Vrain Ranch
Largest-lot (1+ acre) single-family estate community with premium price points ideal for high-rent detached ADUs serving I-25 commuters to Denver/Boulder.
Saddleback Heights
Golf-course-fronted neighborhood with spacious lots and strong family appeal, supporting strong ADU rents from relocating Front Range workers.
Barefoot Lakes
Master-planned lakeside community with large SFH lots and ongoing new construction, giving a steady pipeline of detached-ADU-eligible single-family lots.
Oak Meadows
Ranked #1 best place to live in Firestone (Nextdoor), established SFH community with competitively priced homes and consistent rental demand.
Neighbors Point
High-density SFH subdivision with mid-to-upper price ranges, located near Firestone's commercial corridor for strong rental demand.
The Shores
Waterfront-adjacent SFH community with above-average lot sizes and family-oriented appeal that supports steady ADU rental interest.
Mountain Shadows
Established SFH neighborhood with mountain views and moderate-sized lots, providing classic detached-ADU opportunity near I-25 commute corridor.
Sagebrush
Family-friendly SFH community with roomy yards and proximity to UCHealth Carbon Valley Medical Center, supporting healthcare-worker ADU demand.
Monarch Estates
Well-established SFH community with traditional lot sizes ideal for entry-level detached ADUs targeting Longmont/Boulder commuters.
Stoneridge
Solid SFH subdivision with ample yard space and proximity to local schools, attracting long-term renters needing ADU supplemental housing.
Firestone ADU Market at a Glance
Local Zoning Rules
2026 Firestone ADU Rules
Firestone's 2026 ADU ordinance caps new units at 750 sq ft and 25 ft of height — restrictive, which rules out most 2-bedroom layouts. Setbacks run 5 ft side and 5 ft rear, close to the regional baseline. Firestone doesn't trigger the extra engineer-stamp requirement we see in higher seismic-risk or hurricane-code cities — a standard code-compliant ADU under the size cap can typically be designed and submitted without an architect or engineer stamp, though any load-bearing change to the existing house still needs one.
Permit fees run $4,218–$7,820 — in line with what most homeowners budget for permitting through Planning & Development Department. Submit directly to the department online — link below.
| Regulation | Firestone Allowance |
|---|---|
| Max ADU Size | 750 sq ft |
| Max Height | 25 ft |
| Side Setback | 5 ft |
| Rear Setback | 5 ft |
| Architect / Engineer Stamp | Not required under the size cap* |
| Owner Occupancy | Not required |
| Short-Term Rental | Permitted |
| Coastal Overlay | No |
| Design Review | No |
| HOA Prevalence | 30% of properties |
| Permit Fees | $4,218–$7,820 |
*Load-bearing modifications to the existing house always need an engineer stamp regardless of ADU size. Data verified 2026-08-15T06:10:50.038Z. Always confirm with the Planning & Development Department before designing.
Firestone Permit Process
Firestone ADU Permit Timeline & Fees
Local Financing Resources
Local ADU Lenders in Firestone
These lenders offer HELOC, construction, and renovation loans for ADU projects in Weld County. Compare terms before committing.
Local credit union with a physical Firestone Service Center; HELOC variable rates of 6.50%–9.00% APR over a 300-month term.
Visit Lender ↗Colorado community bank financing up to 80% of as-completed appraisal value with a 12-month interest-only construction term.
Visit Lender ↗Colorado credit union offering construction loans up to $7 million with interest-only payments during the construction phase.
Visit Lender ↗Colorado credit union offering one-time close construction-to-permanent loans, covering land purchase through closing costs.
Visit Lender ↗Specialty ADU lender that factors in the home's after-repair value (ARV), ideal for ADU construction projects.
Visit Lender ↗Build With A Plan is not affiliated with these lenders. Always compare rates and consult a mortgage professional.
Local Build Partners
Vetted ADU Contractors in Firestone
We draw the plans. These contractors build them. Independent — no referral fees paid or received.
Build With A Plan provides drawings only. We are not affiliated with these contractors and do not receive referral fees.
Next Steps
Ready to Move Forward With Your Firestone ADU?
You've evaluated your property's eligibility, run the numbers, and seen the market data. The next step is getting permit-ready architectural drawings to submit to Planning & Development Department.
Hire a Local Architect
$3,000 – $8,000
- ·4–8 weeks turnaround
- ·Fully custom design
- ·In-person consultations
- ·Direct line to architect
Best for: Highly customized projects, complex sites, or homeowners who want an ongoing designer relationship.
Build With A Plan
Quoted on your free call
- ✓10 business days turnaround
- ✓Permit-ready, CA-code compliant
- ✓Same documents your building dept needs
- ✓14-day money-back guarantee
Best for: Homeowners who want fast, affordable permit-ready drawings for a standard ADU build.
Both options produce permit-ready architectural drawings accepted by Planning & Development Department. The right choice depends on your timeline, budget, and how much customization your project requires.
Drawing Package Details
What's Included in Your Firestone ADU Package
Engineered for CO Permit Approvals
What You Get
Firestone ADU Drawings — What's Included
How our permit-ready drawing sets compare to hiring a local architect in Firestone:
| Service Type | Typical Cost | Turnaround | Customization |
|---|---|---|---|
| Local Architect | $3,000 – $8,000 | 4–8 weeks | Fully custom |
| Build With A Plan · Starter | Quoted on your free call | 10 days | Standard |
| Build With A Plan · Standard | Quoted on your free call | 10 days | Standard |
| Build With A Plan · Premium | Quoted on your free call | 5 days | Enhanced |
- ✓Site plan
- ✓Floor plans
- ✓All 4 elevations
- ✓Electrical plan
- ✓CO energy code form
- ✓PDF + DWG delivery
- ✓10 business day turnaround
- ✓Everything in Starter
- ✓Structural plans (stamped)
- ✓Cross-section details
- ✓Window & door schedules
- ✓Material specifications
- ✓1 round of revisions
- ✓Everything in Standard
- ✓3D rendering
- ✓Garage conversion alt plan
- ✓HOA submission package
- ✓2 rounds of revisions
- ✓Priority 5-day turnaround
The Done-For-You Path
Want Your Firestone ADU Fully Done For You?
Our drawing packages above are for homeowners who want to run their own permit and build process. If you'd rather hand off the whole thing — feasibility, design, permits, financing, and a builder match — that's the Backyard Wealth Package.
We turn your backyard into a rental unit. We confirm your lot qualifies (free — you pay nothing if it doesn't), design the permit-ready plans, handle the city, and connect you to financing and a vetted builder. One flat fee — about what an architect charges just to start. Yours would rent around $1,450/mo.
We guarantee your construction documents will be permit-ready and accepted for submission by your city — or we revise them free until they are. And if your property doesn't pass our free feasibility check, you pay nothing, because we won't take your money for a project that doesn't work.
We won't even take your money unless your property qualifies.
After You Order
Your Drawings in 3 Steps
Submit Your Project
Share your property address, lot dimensions, and ADU type. We'll confirm your order and assign your project coordinator.
We Draft Your Drawings
Our team designs your permit-ready drawing set — engineered for Firestone's building department requirements and CO code. Delivered in 10 business days.
Submit to Your City
Download your complete drawing package and submit directly to Planning & Development Department. We support corrections at no extra charge.
Real Projects · Verified Outcomes
ADU Projects Completed with Build With A Plan
Three representative project scenarios based on actual drawing packages delivered in Colorado cities with similar market conditions to Firestone.
Build costs reflect local construction data for Firestone. Client names are initials only. Permit timelines are project-specific and may vary.
"Permit approved on the first submittal. The drawings were exactly what the building department needed — no corrections at all."
"We converted our two-car garage in under 6 months. Drawings were ready in 10 days — faster than any local firm we contacted."
"The JADU drawings included everything the city required. Submitted day 11, approved six weeks later. Tenant moved in two months after that."
Representative scenarios. Build costs modeled using Firestone construction data (city-verified data) and Planning & Development Department. Outcomes vary by project scope and site conditions.
Building Code
Firestone Climate Zone & Energy Code
Colorado Energy Conservation Code (Firestone adopts the International Energy Conservation Code with Colorado amendments; Colorado is a Home Rule state but state law requires local adoption and enforcement of the current IECC — the 2024 IECC with Colorado-specific amendments, including the Colorado Model Electric Ready and Solar Ready Code — setting minimum efficiency standards for building envelope, insulation, air sealing, HVAC, and water heating).
Compare Cities
Firestone vs. Nearby Colorado Cities
Frequently Asked
Firestone ADU Questions
How much does it cost to build an ADU in Firestone? +
What is the maximum ADU size allowed in Firestone? +
How long does the ADU permit process take in Firestone? +
Do I need owner-occupancy to build an ADU in Firestone? +
What's the rental income potential for an ADU in Firestone? +
How much does it cost to get ADU drawings in Firestone? +
What drawings are required for an ADU permit in Firestone? +
Can I convert my garage to an ADU in Firestone? +
What neighborhoods in Firestone are best for ADU investment? +
Is Firestone ADU-friendly? +
How much will an ADU increase my property value in Firestone? +
Can I use my Firestone ADU as a short-term rental (Airbnb / VRBO)? +
Does Firestone's seismic zone affect ADU construction requirements? +
Where do I submit ADU plans in Firestone? +
More Services in Firestone
Free · No Obligation
Not Sure If Your Firestone Lot Qualifies?
Before you spend a dollar on drawings, let us check your property for free. We'll tell you honestly whether your Firestone lot supports an ADU, what it could rent for, and what to do next — no pressure, no sales pitch.
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