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Second-Story Addition in Centennial
Licensed second-story addition services for Centennial and Arapahoe County. Double your living space without moving.
What Centennial requires
Code reference: In Centennial, Colorado, building permits for residential remodel work are governed by the 2021 International Residential Code (IRC) Section R105 (adopted via Centennial Municipal Code Chapter 18 – Building Regulations, per Ordinance 2023-O-06 and related adoptions of the 2021 I-Codes). §R105
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Local Service
Second-Story Addition Services in Centennial, Colorado
Autotelic provides professional second-story addition services throughout Centennial and the surrounding Arapahoe County area. Full second-story additions across the Denver metro with structural engineering, framing, roofing, and complete interior build-out. Commercially licensed and insured. Whether you're in Centennial (south Denver metro) or nearby communities, our team delivers quality workmanship backed by Colorado licensing and full insurance coverage.
Permits & Licensing
Permits in Centennial
Centennial building permits, inspections, and contractor license approvals are handled by the city's Building Division. Permits and contractor licenses must be applied for online through the city's Self-Service Portal, and we handle that process as part of every project. Authority: City of Centennial — Building Division.
Permit Thresholds
Centennial permit thresholds
- Code reference
- In Centennial, Colorado, building permits for residential remodel work are governed by the 2021 International Residential Code (IRC) Section R105 (adopted via Centennial Municipal Code Chapter 18 – Building Regulations, per Ordinance 2023-O-06 and related adoptions of the 2021 I-Codes).§R105
- Code reference
- Typically exempt work (aligning with IRC R105.2 exemptions, with local application) includes:
- Code reference
- One-story detached accessory structures (e.g., sheds) ≤200 sq ft.
- Code reference
- Fences ≤7 ft high; retaining walls ≤4 ft high (measured from bottom of footing).
- Code reference
- Prefabricated swimming pools <24 inches deep.
- Code reference
- Window awnings projecting ≤54 inches.
- Code reference
- Decks ≤200 sq ft, ≤30 inches above grade, and not attached to the dwelling.
- Use tax (not collapsed into a single rate)
- City of Centennial Use Tax of 2.5% applied to the actual cost of materials, plus Arapahoe County Use Tax of 0.25% applied to the actual cost of materials.
Codes are amended regularly — verify current requirements with City of Centennial — Building Division.
Zoning & ADU
Centennial zoning & ADU quick facts
- NC5 — Minimum Lot Area
- 5000 sfNC5
- NC5 — Minimum Lot Width
- 50 ftNC5
- NC5 — Front Setback (min)
- 15'NC5
- NC5 — Side Interior Setback (min)
- 5'NC5
- NC5 — Side Setback Abutting Street (min)
- 10'NC5
- NC5 — Rear Setback (min)
- 15'NC5
- NC5 — Lot Coverage (max)
- 42%NC5
- NC5 — Building Height (max)
- 30'NC5
Codes are amended regularly — verify current requirements with City of Centennial — Building Division.
The build sequence for a Second-Story Addition project
This service is a component of How a Home remodel project works in Centennial.
Energy Code
Centennial energy code quick facts
- Code reference
- Centennial, Colorado, has adopted the 2018 IECC (with the 2021 I-Codes package) as its energy code, with no mention of Denver-specific overlays such as the Denver Green Code or Energize Denver.
- Code reference
- This is enforced by the City’s Building Division under Ordinance No. 2023-O-06 (adopting the referenced codes by reference, effective as part of the 2021/2023 code update package).Ord. No. 2023-O-06
- Code reference
- Centennial is in Climate Zone 5B.
- Code reference
- The code applies to alterations, additions, and remodels per IECC Chapter 5 (existing buildings), with the prescriptive requirements of Chapter 4 (or equivalent U-factor/UA paths) generally applying to new or modified portions of the thermal envelope.
- Code reference
- Key prescriptive requirements relevant to remodels/additions (drawn from 2018 IECC Table R402.1.2 and related sections for CZ 5; these are the base code values with no local amendments identified that alter them):
- Ceiling/attic insulation
- Minimum R-49 (or equivalent U-factor ≤ 0.026).
- Adopting reference
- 2018 IECC R402.1.2 (Table R402.1.2).
- Wood-frame wall insulation
- R-20 cavity or R-13 cavity + R-5 continuous insulation (or equivalent U-factor ≤ 0.060).
Codes are amended regularly — verify current requirements with City of Centennial — Building Division.
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What a second-story addition covers
A second-story addition in the Denver metro adds habitable floor over an existing house: new floor structure, stairs, roof, windows, and usually electrical, mechanical, and plumbing. The existing foundation and walls have to carry the extra load. A municipally licensed Denver general contractor coordinates the project, design professionals, and licensed specialty trades. Cost is project-specific and depends on structure, roof, and how much of the first floor is opened.
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Structure and zoning height
City and County of Denver Community Planning and Development treats second-story additions as structural review items that exceed IRC prescriptive limits. The residential permitting guide asks for a letter of structural integrity sealed by a design professional who personally inspected the existing foundation and building (DBCA 133.3). Zoning height is measured in feet and stories from the front and rear base planes (Denver Zoning Code Sec. 13.1.2). Plans should show allowed versus proposed height.
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Permits and who coordinates the work
Additions typically need zoning, building, and Sewer Use and Drainage (SUDP) reviews, plus electrical, mechanical, and plumbing when those systems change. Denver Energy Code Chapter 5 [RE] applies to additions. Cities and counties license general contractors. Colorado has no statewide general contractor license. Autotelic acts as a municipally licensed Denver general contractor and coordinates licensed specialty trades plus the design professionals required for the project.
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What buyers should prepare
Target rooms, existing drawings if any, roof and attic photos, and known foundation concerns.
FAQ
Common questions
Do second-story additions need a Denver permit?
Yes. CPD requires building, zoning, and typically SUDP, with structural review because the work exceeds IRC prescriptive limits.
Who handles second-story permits and licensing?
A municipally licensed Denver general contractor coordinates the project, design professionals, and specialty trades. Colorado has no statewide general contractor license.
Can the existing foundation take a second story?
Only after a design professional inspects it. CPD asks for a sealed structural-integrity letter for second-story additions.
How is height measured?
In feet and stories from the zoning front and rear base planes, not just from the sidewalk.
What information helps define scope?
Desired rooms, existing drawings, foundation notes, landmark status, and city or county.
Service Area
Serving Centennial and Arapahoe County
We serve Centennial, CO and all surrounding Denver metro communities. Our team is based in Denver and operates throughout the Front Range, from Castle Rock to Longmont and everywhere in between. Contact us for a free estimate on your Centennial project.
How It Runs
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Survey
02
Design
03
Build
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Verify
DESIGN SERVICES
Discovery & Site Analysis
Needs + preference programming, site survey, as-built documentation, feasibility.
We walk, measure, and photograph your property — existing conditions, utilities, structure, and constraints. You get the as-built documentation and feasibility read that every later decision rests on.
Learn more →Concept Design & Space Planning
Schematic design, floor plan studies, layout options.
Your scope becomes schematic floor plans you can compare side by side — circulation, daylight, adjacencies, and what each option does to the budget. Layout decisions happen on paper, where changes are cheap.
Learn more →Architectural Design & 3D Renderings
Design development, materials + finishes, photorealistic visualization.
The chosen concept resolves into materials, finishes, fixtures, and lighting — with the automation layer drawn in. Photorealistic renderings let you walk the space and adjust before anything is priced.
Learn more →Construction Documents & Permitting
Full CD sets, structural + MEP engineering coordination, permit-ready drawings.
Approved designs become coordinated architectural, structural, and MEP sheets — the set your jurisdiction permits from and trades build from. We submit, track, and answer review comments.
Learn more →CONSTRUCTION
New Construction & Custom Homes
Ground-up homes and light commercial, dirt to keys.
Ground-up residential and light commercial builds — foundations through finishes, including modular and steel construction. One accountable builder from dirt to keys.
Learn more →Remodels & Additions
Kitchens, baths, basements, pop-tops, whole-home.
Kitchens, baths, basements, pop-tops, and whole-home renovations that respect the house you already have. We handle structure, permits, and the dust.
Learn more →Commercial Tenant Finish & Build-Outs
Shells to working spaces — retail, office, restaurant, school.
Raw shells become working spaces — showrooms, offices, restaurants, schools. Dealer-spec finishes, code compliance, and opening dates held.
Learn more →ADUs & Modular Construction
Backyard cottages, garage conversions, factory-built homes.
Backyard cottages, garage conversions, and factory-built homes — zoning, design, permits, and set. Denver’s ADU rules are a specialty, not a surprise.
Learn more →Outdoor Living & Patio Structures
Decks, pergolas, and dining patios built for Colorado weather.
Decks, pergolas, and dining patios engineered for Colorado sun, snow, and hail — structure, shade, and drainage done right the first time.
Learn more →TECHNOLOGY
Smart Home Automation
Lighting, shades, climate, audio, security — one interface.
Whole-home control of lighting, shades, climate, audio, and security from a single interface — Crestron, Lutron, Savant, and Control4 designed in, not bolted on.
Learn more →A/V Systems
Theaters, distributed audio, video walls, commercial sound.
Theaters, distributed audio, video walls, and commercial sound — designed, installed, and tuned by the same team for over 20 years.
Learn more →Control Systems
Custom programming — scenes and schedules that fit the space.
Every subsystem brought into one elegant interface — custom programming for homes and venues, with scenes and schedules that match how the space is actually used.
Learn more →Networking & Edge Compute
Enterprise Wi-Fi, structured cabling, racks, on-prem compute.
Enterprise-grade Wi-Fi, structured cabling, racks, and on-premise compute — the backbone that makes everything else reliable, including our own Barbot platform.
Learn more →Solar & Energy Storage
Solar arrays, Tesla Powerwall, EV charging — certified install.
Solar arrays, Tesla Powerwall, and EV charging designed and installed by a Tesla Energy Certified team — roof, electrical, and app in one scope.
Learn more →Let's design your perfect Second-Story Addition together
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