bridge over croke lake with fountain of water and Thornton city buildings in the background


Effective 11/24/2021 the Building Inspection Division counter will be open by appointment only. To request an appointment please contact us at 303-538-7250 or email Masks will be required when inside the building.

Building Inspection Division

The Building Inspection Division is responsible for the Plan Review, Permit Issuance and Inspection of new construction projects and remodel of existing structures in the City of Thornton.

Office Hours are 8 a.m. to 5 p.m. Monday through Friday.  Payment is accepted from 8 a.m. to 4:30 p.m.

ATTENTION SOLAR CONTRACTORS: Effective June 28, 2021, panel upgrades when done in conjunction with any solar permits will require a separate permit.  You can no longer include the panel upgrade as part of the solar permit. If a panel replacement is discovered during an inspection of a solar system, the inspection process will cease until a permit is issued for the upgrade. The permit/inspections, for the new service must be completed before the solar system will be passed. The inspection for the panel upgrade can be done at the same time as the heat meter and final electrical inspections on the solar permit.


Notice to contractors and homeowners: your inspection may be performed by an unmanned aerial vehicle (UAV) commonly known as a Drone. 

Schedule your inspections online through our CityView PortalYou will need to register on the portal in order to schedule inspections. Make sure to follow the instructions for registration under the Portal Help menu. If you are a contractor you will need to log in using your company login. You can schedule your inspection up to 6:30 AM for an inspection THAT day. You can also schedule inspections through the Inspection Request Line 303-538-7396. 

Please leave the following information in this order when scheduling your inspection.

  • Permit Number
  • Project Address
  • Type of Inspection
  • Let us know if this is a Reinspection

Access must be provided to all areas or items needing inspection. If we need access to your back yard to complete the inspection, please give us verbal permission in the request.

  • Please make sure that there are no animals in the back yard.
  • An adult at least 18 years of age shall be present for all required interior inspections.
  • Consultation inspections are available to any permit holder. If the inspection is not available on the permit please call 303-538-7250.

Inspection Times

  • For information on inspections eligible for time windows and how to request a time click on the following link: INSPECTION TIMES

In addition, the following policies regarding inspections have been put in place.

Please click on the topics below to learn more about each section.

 Unoccupied Structure Inspections (New Commercial and New Residential)


We will continue to provide inspections for these projects. Our preference will be to complete the inspection in person as determined by the Field Inspection Supervisor to ensure that the intent of the Code has been met. No one, except vaccinated or masked project superintendents or general contractors, are allowed with the inspector during the inspection. Inspection results and corrections will be available to view on the CityView Portal shortly after the inspection is completed. Vaccinated personnel may be present on the jobsite without masks. It will be the inspector's discretion whether the inspection will be performed. Inspections are required to finalize all building permits that were issued and to receive a Letter of Compliance or Certificate of Occupancy. If you do not want inspections completed during this time and need an extension to your building permit, or if you have any questions, comments or concerns regarding these procedures please contact city staff at or call 303-538-7250.

Paperwork for New Residential projects needs to be uploaded to the CityView portal rather than picked up by the inspectors: Site surveys, Duct leakage tests, Insulation, Final engineer letters and energy documents should be uploaded 1 business day prior to inspection.

New Commercial: Inspections must be in person using the precautions outlined above.

 Occupied Structure Inspections (Homeowner projects and remodels, Commercial TI projects)

We have resumed in-person inspections within occupied structures and will attempt to accommodate the homeowner based on their comfort level with in-person inspections. If a virtual inspection is preferred, please clarify such when scheduling the inspection (**see virtual inspection guidelines below). We will continue to provide in-person inspections for work being done outside of the occupied structure (i.e. roofs, fences, detached garages, etc.).

 **Virtual Inspections (Video Call)

The following is a list of what we believe could be inspected via virtual inspection in an occupied structure: caisson, footing, stem wall, water heater, furnace, AC, rough inspections, drywall, final inspections, final deck/ patio cover, driveway, and fence.

All Roof inspections can be done virtually or with a drone.

All Solar PV inspections will be done virtually.

Basement finish projects may be scheduled for virtual inspection and will be left to the discretion of the inspector whether an inspection can be completed. If at any time the inspector believes he cannot complete an inspection, he may require the inspection be rescheduled at a later date.

*The exception to this rule will be when there is an inspection that is specifically related to safety/health in occupied structures.

**Before scheduling a virtual inspection, please verify you have the following:

  • Google Duo app installed on your mobile device,
  • Wifi connection with a strong 4G or better signal (be sure the signal works outdoors as you will be asked to verify your address in the video)
  • Turn off notifications on your mobile device prior to the video inspection (your connection may freeze or drop the call)
  • Have inspection tools available (tape measure, level, flashlight, GFCI capable outlet tester, step ladder)
  • When scheduling the inspection, provide name and phone number of the person operating the camera. If this information is not provided the inspection will be automatically canceled.

 Restaurants and Temporary Outdoor Seating

The Governor has approved the reopening of restaurants with certain conditions, including encouraging outdoor seating. If you are considering providing temporary shelter for your outdoor seating, please review the following information. Click on each of the links below to open and view each document.

Fire Department Information

The Fire Prevention Division is responsible for the enforcement of City of Thornton laws, codes, and ordinances, including the International Fire Code and nationally recognized standards. Through plan review, inspections, meetings with citizens and design professionals, and continuing education, the Prevention staff works toward the protection of life and property from the effects of fire.

Roofing/Re-Roofing Standards
The City of Thornton has amended the roofing sections of the International Building Code and the International Residential Code to require asphalt shingles to carry a manufacturers national wind warranty for the City’s designated wind speed of 90 mph 3-Second Gust. Please see our Roofing Standards for a list of approved shingles and other roofing requirements.  

Please click here to read the Roofing Inspections Policy effective 6-15-2020

Permit Information

A building permit is required any time you erect, construct, enlarge, remodel, alter, repair, move, improve, remove, convert, demolish, or change the type of occupancy of any building, structure or utility. For a list of projects that require a permit and a list of projects that do not require a permit, click on the Building Permit Requirements link listed under the Permits, License Application section of links.

The process to obtain a permit will vary dependent upon the complexity of the project.  It is our goal to get plans through the system and a permit issued in the minimum amount of time possible.

Plan Review

Once you have all of the information gathered for a complete submittal package, click on the Submittal Requirements. This information and plans can be submitted to the Building Inspection Division for review.  Click here  for information on Electronic Submittal and Plan Review.

The amount of time to process and review a plan from the initial submittal date to the completion of the first review (the turn around time) will vary with the type of project.

  • New Commercial -  15  working days or less
  • Commercial Tenant Improvements & Remodels - 10 working days or less
  • New Residential except multifamily - 10 working days or less
  • Residential Remodels and Misc - 5 working days or less

Permit Issuance

Once all approvals have been completed, the application is prepared for permit issuance by the permit technician staff.  They will verify that all contractors are currently licensed, all permission forms have been received and calculate the permit fee.  Once this is complete, you will be notified that the permit is ready for issuance.  Following payment of fees, you will receive the building permit, permit card and the field set of plans. Please see the Inspections page for information about the inspection phase of your project.

Code & Amendments

Adopted Codes for the City of Thornton

  • 2018 International Building Code
  • 2018 International Residential Code
  • 2018 International Plumbing Code
  • 2018 International Mechanical Code
  • 2018 International Fuel Gas Code
  • 2018 International Existing Building Code
  • 2018 International Energy Conservation Code
  • 2018 International Swimming Pool and Spa Code
  • 2018 International Fire Code
  • 2017 National Electric Code