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LONGMONT SERVICES
Second-Story Addition in Longmont
Licensed second-story addition services for Longmont and Boulder County. Double your living space without moving.
What Longmont requires
Code reference: Longmont adopted the 2024 International Codes (including the energy code) along with the Metro Cohort Model Code (MCMC, based on the 2024 IECC with regionally aligned amendments) via Ordinance O-2026-29 (adopted ~June 9, 2026; see Municode Chapter 16.22 for the energy conservation code adoption). Ord. O-2026-29
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Local Service
Second-Story Addition Services in Longmont, Colorado
Autotelic provides professional second-story addition services throughout Longmont and the surrounding Boulder 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 Longmont (north Boulder County) or nearby communities, our team delivers quality workmanship backed by Colorado licensing and full insurance coverage.
Permit Thresholds
Longmont permit thresholds
- Code reference
- The City of Longmont has adopted the 2024 International Codes, including the International Residential Code, effective July 1, 2026.
- Code reference
- Retaining walls over 48 inches.
- Code reference
- Accessory buildings over 120 square feet.
- Code reference
- Accessory buildings 120 square feet or less in floor area, though it is recommended to secure them against wind damage, and they must still meet setback requirements.
- Code reference
- Fencing below certain heights (commonly 6 feet).
- Foundations
- For one-story accessory structures greater than 120 square feet, foundations must be designed by a Colorado-licensed engineer, and the drawings must be stamped and sealed by that engineer.
- Code reference
- The City of Longmont enforces the 2024 International Codes, which became effective on July 1, 2026, along with the Metro Cohort Model Code.
- Code reference
- The Longmont Municipal Code incorporates by reference the International Residential Code for One and Two-Family Dwellings, 2021 Edition, including various appendix chapters.
Codes are amended regularly — verify current requirements with **The City of Longmont Building Services (Building Inspection division) issues residential building permits.
Zoning & ADU
Longmont zoning & ADU quick facts
- Code reference
- The most common single-family residential districts that permit ADUs are Rural Residential (R-RU), Residential-Single Family (R-SF), and Residential-Mixed Neighborhood (R-MN).
- Code reference
- ADUs are permitted as an accessory use in the R-RU, R-SF, and R-MN zoning districts, among others.
- Code reference
- General ADU standards are found in Longmont Municipal Code (LMC) Sections 15.04.040 and 15.02.080.E.
- Code reference
- An ADU cannot exceed one-half (50%) of the finished, above-ground floor area of the main house.
- Code reference
- An ADU may total up to 800 square feet regardless of the principal dwelling's size.
- Code reference
- An ADU can be larger than 800 square feet if it does not exceed 50% of the finished, above-ground floor area of the principal dwelling.
- Code reference
- If an ADU is part of a garage structure, the combined area of the garage and habitable ADU space cannot exceed 800 square feet or 50% of the finished, above-ground floor area of the principal dwelling, whichever is greater.
- Code reference
- (LMC Sections 15.04.040.C.2 and 15.02.080.E.3)
Codes are amended regularly — verify current requirements with **The City of Longmont Building Services (Building Inspection division) issues residential building permits.
The build sequence for a Second-Story Addition project
This service is a component of How a Home remodel project works in Longmont.
Energy Code
Longmont energy code quick facts
- Code reference
- 2024 IECC (Metro Cohort Model Code based on the 2024 International Energy Conservation Code, with local/regional amendments), effective July 1, 2026.
- Code reference
- Longmont adopted the 2024 International Codes (including the energy code) along with the Metro Cohort Model Code (MCMC, based on the 2024 IECC with regionally aligned amendments) via Ordinance O-2026-29 (adopted ~June 9, 2026; see Municode Chapter 16.22 for the energy conservation code adoption).Ord. O-2026-29
- Code reference
- This aligns with Colorado state requirements for jurisdictions updating codes around this period (must meet or exceed 2021 IECC + electric/solar-ready provisions, with amendments not reducing stringency).
- Code reference
- Longmont follows its policy of adopting each new IECC version; it is not the Denver Green Code or Energize Denver program.
- Code reference
- Longmont is in IECC Climate Zone 5B.
- Code reference
- Key prescriptive requirements (from the adopted 2024 IECC/MCMC base provisions, applicable to additions and alterations per the IECC scope for new construction elements in remodels/additions) relevant to remodels/additions in CZ 5B include (specific MCMC amendments may modify details; always verify
- Ceiling/attic insulation
- R-49 (or equivalent U-factor per Table R402.1.2/R402.1.3).
- Adopting ordinance/reference
- MCMC/2024 IECC Table R402.1.2 (or R402.1.3 component performance alternative) as adopted in Longmont Municipal Code Chapter 16.22.
Codes are amended regularly — verify current requirements with **The City of Longmont Building Services (Building Inspection division) issues residential building permits.
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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 Longmont and Boulder County
We serve Longmont, 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 Longmont project.
How It Runs
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Survey
02
Design
03
Build
04
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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