ADU Design Resource · Littleton, CO
The Complete Guide to
Building an ADU in Littleton, CO
Everything Littleton 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 Littleton, CO ADUs
Market Context
Littleton has a median home value of $520,000. Adding an ADU typically increases that by 23% — approximately $119,600 in added equity. A 1-bedroom ADU in Littleton rents for approximately $1,503/month in the Arapahoe County rental market , yielding a 6.3% cap rate on the investment. Occupancy averages 92% in this market.
Top Littleton neighborhoods for ADU investment include Historic Downtown Littleton, Shadycroft Acres, Bow Mar, Grant Ranch, Ken Caryl. High walkability and strong rental demand near downtown jobs make small detached ADUs lucrative. Very large (1+ acre) lots and older single-family homes provide excellent space for detached ADUs.
Permit Process
Permit applications are reviewed by the Building & Development , with a plan check timeline of approximately 6 weeks. Permit fees in Littleton range from $10,959 to $22,802 depending on project scope. Design review: Yes - in historic districts only
Littleton's Building & Development Department will flag your ADU application if your lot sits on one of the older South Littleton or Ketring Lake area water taps, since many of those lines were sized decades ago for single-family use only — you'll likely need a separate Arapahoe County water tap upgrade before final approval, which isn't something the standard permit checklist warns you about. Also, if your property falls within one of Littleton's older platted subdivisions with restrictive covenants (common near Downtown and Historic Littleton), the city permit can get approved while your HOA or covenant enforcement still blocks construction, so it's worth pulling the covenant document early rather than assuming city sign-off is the finish line. Because STRs are allowed citywide, expect extra scrutiny on your parking plan if you mention short-term rental intent anywhere in your application — reviewers tend to slow-walk those files for a closer look at access and setback compliance.
"In my experience, that 6-week timeline and $375/sqft figure are Littleton state-level estimates rather than verified local numbers, so I'd get actual contractor quotes and call Building & Development directly before penciling in a schedule or budget. I've also seen plenty of "under 8 week" submittals stretch out considerably once corrections come back on an incomplete drawing set, so don't bank on the fast track unless your plans are airtight going in. —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 Littleton's building department records and current 2026 Colorado's HB24-1152 ADU law.
Property Eligibility
Is My Littleton, CO Property Eligible for an ADU?
Littleton 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 Littleton under Colorado's HB24-1152 (2024). No owner-occupancy requirement in Littleton — you can rent both units as investment properties. Colorado doesn't set a fixed statutory review-day count — confirm the current timeline with the Building & Development.
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 Littleton's local rules. Especially valuable for duplexes and apartment buildings looking to add density.
HOA-Governed Properties
Approximately 30% of Littleton 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.
Historic Districts
Yes - in historic districts only
Always verify eligibility with Building & Development before designing.
Free — No Obligation
Will Littleton Approve an ADU on Your Lot?
Send us the address and we’ll check it against Littleton’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 Littleton 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
Littleton ADU Return Calculator — Built With 2026 Local Data
Pre-loaded with verified Littleton 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 × 23% 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: Building & Development (source ↗), Zillow Rental Market Reports, and public state/local housing data. Last verified: 2026-07-12.
Local Market Data
Top Littleton Neighborhoods for ADU Investment
Historic Downtown Littleton
High walkability and strong rental demand near downtown jobs make small detached ADUs lucrative.
Shadycroft Acres
Very large (1+ acre) lots and older single-family homes provide excellent space for detached ADUs.
Bow Mar
High-income, single-family lake community with spacious lots and demand for additional rental/in-law units.
Grant Ranch
Suburban single-family neighborhood with many mid-to-large lots and good commuter access to jobs.
Ken Caryl
Family-oriented single-family area with amenities and transit access supporting rental demand for ADUs.
Chatfield Bluffs (Columbine area)
Moderately priced single-family neighborhood near C‑470 and regional amenities with commuter rental demand.
Columbine Hills / Columbine Knolls
Established SFH neighborhoods with yards and lot sizes commonly large enough for detached ADUs.
Roxborough Park
Large lots, outdoor amenities and lower housing density make detached ADUs feasible and attractive to renters.
Sterling Ranch
New master-planned community with buildable lots and growing local services creating rental demand.
Marston Lake area
Mix of single-family homes near Marston Reservoir and shopping — good commuter access and yard space for ADUs.
Littleton ADU Market at a Glance
Local Zoning Rules
2026 Littleton ADU Rules
Littleton's 2026 ADU ordinance caps new units at 1,000 sq ft and 18 ft of height — in the typical range most ADU floor plans are designed around. Setbacks run 5 ft side and 5 ft rear, close to the regional baseline. Littleton 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 $10,959–$22,802 — among the higher permit costs we track, and plan check takes about 6 weeks at Building & Development. Submit directly to the department online — link below.
| Regulation | Littleton Allowance |
|---|---|
| Max ADU Size | 1,000 sq ft |
| Max Height | 18 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 | Yes - in historic districts only |
| HOA Prevalence | 30% of properties |
| Permit Fees | $10,959–$22,802 |
*Load-bearing modifications to the existing house always need an engineer stamp regardless of ADU size. Data verified 2026-07-12T23:00:00.000Z. Always confirm with the Building & Development before designing.
Littleton Permit Process
Littleton ADU Permit Timeline & Fees
ℹ Timeline and fee estimates are based on Colorado state averages. Actual Littleton data coming soon.
Local Financing Resources
Local ADU Lenders in Littleton
These lenders offer HELOC, construction, and renovation loans for ADU projects in Arapahoe County. Compare terms before committing.
Offers HELOCs (interest-only draw option) with rates shown as low as 6.75% APR and 10-year draw + 15-year repayment typical—suitable for phased ADU builds.
Visit Lender ↗Offers HELOCs with long-term options (standard terms up to ~240 months; variable options up to ~300 months) and local Colorado lending—usable for ADU/renovation projects.
Visit Lender ↗Provides HELOCs (rates quoted as low as 6.99% variable) and also lists construction loan products—local underwriting and loans up to typical HELOC limits (investment property up to $250k shown).
Visit Lender ↗ChoiceLine HELOC with 10-year draw, interest-only payment option, ability to lock up to three fixed-rate advances—commonly used for home remodels and additions.
Visit Lender ↗Offers construction-to-permanent (new construction) loans with uninterrupted financing and extended rate locks (rate lock up to 270 days)—suitable 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 Littleton
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 Littleton 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 Building & Development.
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 Building & Development. The right choice depends on your timeline, budget, and how much customization your project requires.
Drawing Package Details
What's Included in Your Littleton ADU Package
Engineered for CO Permit Approvals
What You Get
Littleton ADU Drawings — What's Included
How our permit-ready drawing sets compare to hiring a local architect in Littleton:
| 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 Littleton 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 $1,503/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 Littleton'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 Building & Development. 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 Littleton.
Build costs reflect local construction data for Littleton. Client names are initials only. Permit timelines are project-specific and may vary.
"We'd been quoted $6,200 by a local firm for the same permit-ready set. Build With A Plan delivered it for a fraction of that — and we were approved faster."
"Conversion permit came back approved on the first review. The drawings handled every detail — egress, HVAC, electrical. Nothing was missing."
"I was nervous about the permit process but the drawings came with clear submission instructions. Approved without a single correction cycle."
Representative scenarios. Build costs modeled using Littleton construction data (city-verified data) and Building & Development. Outcomes vary by project scope and site conditions.
Building Code
Littleton Climate Zone & Energy Code
Colorado Energy Code / Model Low Energy and Carbon Code (MLECC): Colorado requires local jurisdictions to adopt the 2021 IECC with electric/solar-ready amendments, transitioning to the 2024 IECC-based MLECC for any code updates after July 1, 2026.
Compare Cities
Littleton vs. Nearby Colorado Cities
| City | Build Cost/sqft | Permit Fees | 1BR ADU Rent | Cap Rate | Eligibility |
|---|---|---|---|---|---|
| Littleton ← you | $375 | $10,959+ | $1,503/mo | 6.3% | Free check → |
| Aurora | $300 | $11,327+ | $1,248/mo | 5% | View → |
| Centennial | $300 | $3,200+ | $2,100/mo | 5.2% | View → |
| Englewood | $300 | $2,510+ | $1,200/mo | 5.2% | View → |
| Greenwood Village | — | — | $1,800/mo | 5.4% | View → |
Frequently Asked
Littleton ADU Questions
How much does it cost to build an ADU in Littleton? +
What is the maximum ADU size allowed in Littleton? +
How long does the ADU permit process take in Littleton? +
Do I need owner-occupancy to build an ADU in Littleton? +
What's the rental income potential for an ADU in Littleton? +
How much does it cost to get ADU drawings in Littleton? +
What drawings are required for an ADU permit in Littleton? +
Can I convert my garage to an ADU in Littleton? +
What neighborhoods in Littleton are best for ADU investment? +
Is Littleton ADU-friendly? +
How much will an ADU increase my property value in Littleton? +
Can I use my Littleton ADU as a short-term rental (Airbnb / VRBO)? +
Does Littleton's seismic zone affect ADU construction requirements? +
Where do I submit ADU plans in Littleton? +
More Services in Littleton
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