DESIGN · BUILD · AUTOMATE
LONGMONT SERVICES
ADU / Backyard Cottage in Longmont
Licensed ADU / backyard cottage services for Longmont and Boulder County. Build an income-producing unit in your backyard.
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
See full local requirements ↓- Full Design Lifecycle
- Construction & Tenant Finish
- Smart Home · A/V · Edge Compute
Build an income-producing unit in your backyard
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EVERY PROJECT STARTS WITH DESIGN
Local Service
ADU / Backyard Cottage Services in Longmont, Colorado
Autotelic provides professional ADU / backyard cottage services throughout Longmont and the surrounding Boulder County area. Accessory dwelling unit construction across the Denver metro — detached new builds, garage conversions, and basement conversions compliant with Colorado HB 24-1152. One veteran-owned design-build team runs the full Denver sequence under a single contract: zoning verification and concept design, municipal zoning and building permit reviews, then construction and inspections through certificate of occupancy. 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.
A recent build
Backyard ADU in Denver
Denver · 2026
- Status
- Under construction — 2026
- Managed on
- Buildbot — Autotelic’s own PM platform
- Architecture, site plans, and full MEP design completed in-house
- Permits pulled — electric and plumbing rough-ins permitted and underway
- Spray-foam insulation and exterior work in progress
- First project managed end-to-end on Buildbot, Autotelic’s construction-PM platform
A ground-up backyard ADU in Denver — designed, permitted, and now under construction by Autotelic, and the first project managed end-to-end on Buildbot, Autotelic’s own construction-management platform.
The build sequence for a ADU / Backyard Cottage project
This service is a component of How a ADU 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 this covers
Detached or attached accessory dwelling on a Denver lot: foundation or module, envelope, and utility tie-in. Height and massing follow Denver bulk-plane and ADU rules for the zone; confirm with CPD before drawings freeze.
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How the work is coordinated
A municipally licensed Denver general contractor coordinates licensed specialty trades for electrical and plumbing. Denver-metro work is permitted locally. Colorado has no statewide general-contractor license. Cities and counties license general contractors. DORA licenses electrical and plumbing (and similar regulated trades), not general contractors. Autotelic is a municipally licensed Denver general contractor that coordinates licensed specialty trades. Denver building permits run through Community Planning and Development (CPD). Costs are project-specific; no dollar figures.
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.
FAQ
Common questions
Is an ADU allowed on my lot?
It depends on your city’s zoning — lot size, setbacks, and parking rules vary across the metro. We run the zoning check as the first step and tell you what your lot supports before you spend money on design.
Do you handle ADU permits and inspections?
Yes — ADU permitting is municipal, and we manage zoning review, permit application, and every inspection through certificate of occupancy.
Detached, attached, or garage conversion — which is right?
Each has different zoning, cost, and site implications. We design all three and recommend based on your lot, budget, and how you plan to use the unit.
What does an ADU cost?
Getting a real answer costs less than most people expect: an ADU feasibility consultation is $350, and the full ADU feasibility package — zoning check, site analysis, and concept direction — is $950, both listed at fixed prices on our booking page. Construction cost depends on the path: garage and basement conversions reuse existing structure, while a detached backyard cottage is new construction from the foundation up. After feasibility we quote the build itself as a fixed-price proposal, so you know the number before work starts.
How long does an ADU project take?
Three phases run in sequence: design (site measure, concept, construction documents), permitting (zoning and building review, which move on the municipality’s calendar), then construction. Conversions generally move faster than detached new builds because the shell and foundation already exist. We lay out the phase-by-phase schedule in your proposal, and you track progress on our operations platform once work starts.
How small a lot can support an ADU?
Smaller than most people assume — many Front Range single-unit lots that owners write off can carry a detached unit, and each city sets its own minimum lot size, setbacks, and building coverage. Whether your district’s standards leave room for a backyard cottage — or point you toward a garage or basement conversion instead — is exactly what the feasibility check answers for your address.
What is the ADU permit process?
Two municipal reviews run in order: a zoning review confirming the unit fits your district’s standards, then a building permit review of the construction documents, with inspections during the build and a certificate of occupancy at the end. Colorado HB 24-1152 now requires most Front Range municipalities to allow ADUs on single-unit lots, and we confirm how your city implements it as the first step of feasibility.
How It Runs
01
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 ADU / Backyard Cottage together
Get a personalized estimate in about 2 minutes — no pressure, no obligation.
How This Works (2 minutes)
- 1Tell us about your project (30 seconds)
- 2Answer a few quick questions for an accurate estimate (60 seconds)
- 3Get your personalized estimate instantly (30 seconds)
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