Colorado Building Codes, Permits and Contractor Rules
Here’s every rule from our 50-state guides for Colorado on one page: the residential building code, frost depth, retaining wall permits, the 811 dig law, drainage law, contractor licensing, deposit limits, mechanics lien deadlines, workers’ comp, planting zones and frost dates. Each section links the official source and the full 50-state comparison.
Colorado at a glance
- Building code: Set by cities and counties
- Frost depth: Set locally; often 30-36 in.
- 811 notice: At least 2 full business days before excavation, not counting the day of notice
- Contractors: No statewide requirement (local)
- Deposits: No cap; roofing payments held in trust
- Liens: 4 months from last furnishing
- Workers’ comp: 1+ employees
- Drainage rule: Civil law (natural flow)
- Planting zones: 3b to 7a
| Topic | Colorado | Compare |
|---|---|---|
| Residential building code | Set by cities and counties | All states |
| Frost line depth | Set locally; often 30-36 in. | All states |
| Retaining wall permit | Set locally | All states |
| 811 notice before digging | At least 2 full business days before excavation, not counting the day of notice | All states |
| Contractor license | No statewide requirement (local) | All states |
| Deposit limit | No cap; roofing payments held in trust | All states |
| Right to cancel | 3 business days, credit sales at home | All states |
| Lien filing deadline | 4 months from last furnishing | All states |
| Workers’ comp required | 1+ employees | All states |
| Drainage between neighbors | Civil law (natural flow) | All states |
| Planting zones (2023 USDA) | 3b to 7a | All states |
| Frost dates (NOAA) | Last frost late Apr (Grand Junction) to early Jun (Alamosa); first frost mid-Sep (Alamosa) to mid-Oct (Grand Junction) | All states |
Colorado residential building code
- Code
- No statewide residential code; cities and counties adopt their own (often a recent IRC)
- How it applies
- Local adoption (no statewide residential code)
- Code agency
- None for private homes (the Office of the State Architect sets codes for state-agency buildings)
- Who enforces it
- Cities and counties adopt and enforce their own codes; areas that have not adopted a code may have no building permits or inspections.
- Good to know
- Colorado has no statewide house code. Your city or county decides which code applies, so the edition can differ from one side of a county line to the other.
Compare building codes in all 50 states
Frost line depth in Colorado
- Who sets it
- Local building department
- Local examples
- City of Aurora: 36 in.
City of Greeley: 30 in.
Town of Eagle: 48 in. - Typical range
- 30-36 in. on the Front Range (Greeley, Aurora); 40-48 in. in mountain towns (Blue River, Eagle)
- Good to know
- Blue River's posted table lists 40 in. For Denver or the Pikes Peak Regional area, check with the building department directly.
Frost line depth in every state
Retaining wall permits in Colorado
- Permit exemption
- Set locally
- Who decides
- Your city or county decides. The state Division of Housing covers certain hotels and multifamily buildings in no-code areas, not single-family homes.
- Good to know
- Colorado has no statewide building code, so your city or county sets the rules for single-family homes.
Retaining wall permit rules in every state
811 dig law in Colorado
- One-call center
- Colorado 811 (Utility Notification Center of Colorado)
- Notice before digging
- At least 2 full business days before excavation, not counting the day of notice
- Ticket good for
- Marks valid while clearly visible, but not more than 30 calendar days after the locate request's due date
- Hand-dig zone
- 18 in. horizontally from the exterior sides of the facility (nondestructive methods required)
- Homeowners
- Yes, homeowners are not excluded from 'excavation' (covers 'any tools'). Excluded: routine maintenance of an existing planted landscape (done at least yearly) disturbing no deeper than 12 in. by nonmechanical means or 4 in. by mechanical means, plus routine farm/ranch work by a farmer or rancher. Homeowners working on their own property are exempt from the statute's civil penalties for failing to notify.
- The law
- C.R.S. § 9-1.5-101 et seq.
- Good to know
- Marks for certain government unpaved-road maintenance up to 6 in. can last up to 180 days. Homeowners on their own property must still call, but the law's civil penalties for not calling don't apply to them.
Drainage law and stormwater permits in Colorado
- Rule
- Civil law (natural flow)
- The rule
- Modified civil law (the Colorado Supreme Court's name for it): an upper owner may alter natural drainage conditions, provided the water is not sent down in a manner or quantity that does more harm to the lower land than before.
- Leading case
- Hankins v. Borland (as applied in Bittersweet Farms, Inc. v. Zimbelman). Hankins v. Borland, 163 Colo. 575, 431 P.2d 1007 (1967); Bittersweet Farms, Inc. v. Zimbelman, Colo. App. No. 97CA0339 (July 23, 1998)
- What it means for your yard
- Water may keep draining downhill the way it naturally does, and you can change your drainage, but not in a way that sends water onto your neighbor in a more harmful manner or volume than before.
- Construction stormwater permit
- Colorado Department of Public Health and Environment (CDPHE), Water Quality Control Division: 1 acre or more of disturbance, or part of a common plan of development or sale (General Permit COR400000, effective April 1, 2024 to March 31, 2029)
- State rules below 1 acre
- No statewide rule below the 1-acre permit found; check your county and town.
- Local rules
- Colorado cities and counties often require grading, erosion control or stormwater permits for smaller projects; check locally.
- Good to know
- In Colorado, natural drainage onto lower land is allowed, but you can't change it in a way that does more harm to your neighbor than before. State construction stormwater permits start at 1 acre.
Contractor licensing in Colorado
- Statewide rule
- No statewide requirement (local)
- Who needs it
- No state general contractor license; the state tells homeowners to check with the city or county that the general contractor is licensed there.
- Licensed separately
- Electrical and plumbing work is licensed by the state (Department of Regulatory Agencies).
Contractor license requirements in every state
Contractor deposits and your right to cancel in Colorado
- Deposit limit
- No statewide cap. Residential roofing contractors must hold any payment from the owner in trust until roofing materials are delivered to the site or a majority of the roofing work is done (C.R.S. § 6-22-103(2)).
- Right to cancel
- Home solicitation sales on credit: 3 business days (C.R.S. §§ 5-3-401, 5-3-402; covers consumer credit sales only). Residential roofing: the contract must let the owner rescind within 72 hours of signing for a full refund of any deposit (§ 6-22-103(1)(f)), and the owner may rescind within 72 hours after an insurer denies the roof claim in whole or part, with payments returned within 10 days (§ 6-22-104). For cash sales at your home, the federal 3-day Cooling-Off Rule applies.
- Written contract
- No general home improvement contract law. Residential roofing work requires a written contract signed by both parties before work begins, including the cancellation and refund policy and a statement that payments are held in trust (C.R.S. § 6-22-103).
- Other protections
- Roofing deposits held in trust until materials are delivered or most of the work is done (C.R.S. § 6-22-103(2)). The roofer cannot waive or rebate an insurance deductible.
- The law
- C.R.S. §§ 5-3-401 to 5-3-405 (home solicitation sales); C.R.S. §§ 6-22-101 to 6-22-105 (residential roofing)
- Good to know
- Colorado has no general deposit cap, but a residential roofer must hold your payment in trust until materials arrive or most of the work is done. Insurance roof jobs can be cancelled within 72 hours after the insurer denies the claim.
Contractor deposit limits in every state
Mechanics lien deadlines in Colorado
- Lien deadline (prime)
- Record the lien statement before 4 months after the day the claimant last performed labor or furnished materials (C.R.S. 38-22-109(5)). Laborers paid by the day or piece: within 2 months after the structure is completed (§ 38-22-109(4)).
- Lien deadline (sub/supplier)
- Same as prime.
- Preliminary notice (sub/supplier)
- Not required (same optional extension notice, C.R.S. 38-22-109(10)).
- Notice of intent
- Required: notice of intent to file a lien statement served on the owner (or reputed owner or agent) and the principal contractor at least 10 days before filing, personally or by certified or registered mail; record an affidavit of service with the lien (C.R.S. 38-22-109(3)).
- Enforce within
- Action to enforce plus a recorded notice of the action within 6 months after the last work or materials, or completion of the improvement (C.R.S. 38-22-110). The clock does not run from the filing date.
- Homeowner rules
- Owners of an existing single-family home or an owner-occupied primary residence have an affirmative defense if they paid the full contract price plus change orders to the contractor or a sub (C.R.S. 38-22-102(3.5)).
- The law
- C.R.S. Title 38, Art. 22 (General Mechanics' Lien), § 38-22-101 et seq.
- Good to know
- Colorado requires a notice of intent to the owner and general contractor at least 10 days before filing, and the lawsuit is due within 6 months of your last work, not 6 months after filing. Owners of an existing single-family home or an owner-occupied home who paid the contractor in full have a defense.
Mechanics lien deadlines in every state
Workers' comp requirements in Colorado
- Who must carry it
- All businesses with employees operating in Colorado must carry coverage, regardless of the number of employees and even if they work part-time or are family members (Colorado Division of Workers' Compensation). Construction businesses must carry coverage or file a rejection even if the business is a sole proprietorship or partnership with no employees (CDLE).
- Owners and officers
- Corporate officers and LLC members are employees, but those who own at least 10% of the company and hold a specified officer role (or are LLC members taking part in daily operations or management) may reject coverage by filing a rejection (CDLE; C.R.S. § 8-41-202). Sole proprietors and partners in construction must carry coverage or file a rejection (CDLE).
- Subcontractors
- A business that contracts out work is the statutory employer of the contractor's and subcontractors' workers and must insure them, recovering the cost from the contractor; if the contractor is itself insured, the contractor's workers cannot sue the hiring business (C.R.S. § 8-41-401(1)-(2)).
- Homeowners
- The comp law does not apply to the owner or occupant of a 'qualified residence' (IRC § 163(h)(4)(A)) who contracts out work on the property, unless the worker is otherwise that owner's employee (C.R.S. § 8-41-402(1)).
- Penalties
- Uninsured employers can be fined up to $500 for every day they are uninsured (the statute sets up to $250 a day for a first violation and $250 to $500 a day for later ones), and their business may be shut down; if a worker is hurt, the employer pays the claim itself plus a penalty of 25% of the worker's benefits (CDLE insurance requirements page; C.R.S. §§ 8-43-408, 8-43-409(1)(b)).
- The law
- C.R.S. Title 8, Arts. 40-47; §§ 8-41-202, 8-41-401, 8-41-402, 8-43-409
- State agency
- Colorado Department of Labor and Employment, Division of Workers' Compensation
- Good to know
- Colorado requires coverage with one employee, and construction sole proprietors must carry it or file a rejection. A homeowner who hires a contractor to work on their own home is not treated as the contractor's employer under the comp law.
Workers' comp requirements in every state
Planting zones in Colorado
- 2023 USDA zones
- 3b to 7a
- Coldest-night range
- −35°F to 5°F
- Warmest area
- The Grand Valley around Grand Junction
- Example cities
- Denver: 6a, Colorado Springs: 6a, Fort Collins: 5b, Grand Junction: 7a
- Good to know
- Colorado's zones follow elevation more than latitude. Denver and Colorado Springs are 6a and the Grand Valley around Grand Junction is 7a, while the high mountains are much colder.
Frost dates in Colorado
| Station | Last spring frost | First fall frost | Frost-free days |
|---|---|---|---|
| Denver Front Range | May 5 | October 9 | 156 |
| Pueblo Arkansas Valley, southeast | April 30 | October 9 | 161 |
| Grand Junction Western Slope | April 28 | October 16 | 171 |
| Alamosa San Luis Valley | June 7 | September 15 | 98 |
- Typical range
- Last frost late Apr (Grand Junction) to early Jun (Alamosa); first frost mid-Sep (Alamosa) to mid-Oct (Grand Junction)
- Good to know
- These are typical (50%) dates from NOAA's 1991–2020 climate normals, so about half of years still bring a 32°F night after the listed spring date. In Colorado, the last spring frost at the stations listed ranges from late April around Grand Junction to early June around Alamosa.
- Local frost or planting guide
- Colorado State University Extension
Frequently Asked Questions
What building code does Colorado use?
No statewide residential code; cities and counties adopt their own (often a recent IRC). It applies as follows: local adoption (no statewide residential code). Your local building department can confirm the edition and amendments for your address.
How deep is the frost line in Colorado?
Frost depth is set by local building departments. Typical local values: 30-36 in. on the Front Range (Greeley, Aurora); 40-48 in. in mountain towns (Blue River, Eagle). Footings for houses, additions and attached decks go below it.
How much can a contractor ask for up front in Colorado?
No statewide cap. Residential roofing contractors must hold any payment from the owner in trust until roofing materials are delivered to the site or a majority of the roofing work is done (C.R.S. § 6-22-103(2)). Cancel rights: Home solicitation sales on credit: 3 business days (C.R.S. §§ 5-3-401, 5-3-402; covers consumer credit sales only). Residential roofing: the contract must let the owner rescind within 72 hours of signing for a full refund of any deposit (§ 6-22-103(1)(f)), and the owner may rescind within 72 hours after an insurer denies the roof claim in whole or part, with payments returned within 10 days (§ 6-22-104). For cash sales at your home, the federal 3-day Cooling-Off Rule applies.
How long does a contractor have to file a mechanics lien in Colorado?
Record the lien statement before 4 months after the day the claimant last performed labor or furnished materials (C.R.S. 38-22-109(5)). Laborers paid by the day or piece: within 2 months after the structure is completed (§ 38-22-109(4)). Subcontractors and suppliers may have different notice rules; see the section above.
What planting zone is Colorado?
On the 2023 USDA map, Colorado runs from zone 3b to 7a. Examples: Denver 6a, Colorado Springs 6a, Fort Collins 5b. Enter your ZIP on the USDA map for your exact zone.
Do contractors need workers' comp in Colorado?
All businesses with employees operating in Colorado must carry coverage, regardless of the number of employees and even if they work part-time or are family members (Colorado Division of Workers’ Compensation). Construction businesses must carry coverage or file a rejection even if the business is a sole proprietorship or partnership with no employees (CDLE). Owner exemptions and subcontractor rules are in the workers’ comp section above.
When is the last frost in Colorado?
At the NOAA stations we list: Last frost late Apr (Grand Junction) to early Jun (Alamosa); first frost mid-Sep (Alamosa) to mid-Oct (Grand Junction). These are typical (50%) dates from the 1991–2020 climate normals, so about half of years still bring a 32°F night after the spring date.
This page is general information, not legal or tax advice. Rules change; the agencies and statutes linked above have the final word.
Colorado in each 50-state guide: Frost line depth · 811 dig laws · Retaining wall permits · Contractor licensing · Contractor deposit limits · Building codes · Planting zones · Mechanics lien deadlines · Workers' comp · Frost dates · Drainage laws · Noxious weed laws · Rainfall and snowfall · Landscaper pay · Pesticide applicator licensing · Landscaping sales tax · All state guides
Last checked October 31 and November 1, 2026 against official state and local sources for this state. Rules change; your state agency or local building department has the final word. Spot something out of date? Email info@muthlerlandscaping.com and we’ll fix it.
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Cite as: Muthler Landscaping & Construction, “Colorado Building Codes, Permits and Contractor Rules,” https://muthlerlandscaping.com/state-guides/colorado/ (last checked November 9, 2026).
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