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Building Inspection Division


EFFECTIVE Thursday 3/26/2020

Due to the impact of Covid-19, please be advised that the building inspection division is closed to the public until at least April 30th. We are available by telephone 303-538-7250 and email You can still submit applications via the portal or via email and we will be providing limited inspections between 8:30am – 4:00pm, Monday through Friday.  The 2-hour request for homeowner inspections has been suspended until further notice.

In order to protect the health and safety of our customers and city building inspectors during the current Stay at Home order, the following policies regarding inspections have been put in place:

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 via video/photo but will have to complete in person inspections as determined by the Field Inspection Supervisor to ensure that the intent of the Code has been met.  We will require that the structure be vacated for the day until the inspection has been completed. We will reach out to the applicant after each inspection to notify them that they can return to work within the structure. No one is allowed on site during the inspection and we will also be wearing gloves and masks during the in-person inspection. 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 completion.  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 or call 303-538-7250.

The following is a list of what we believe could be inspected via video/photo.

New Residential: Site surveys (can be emailed), Mid-roofs/Roofs (drone), Lath, Duct leakage test (can be emailed), Insulation (3rd party can be emailed), Final engineer letters and energy documents (can be emailed).

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

Occupied Structure Inspections – (Homeowner projects and remodels, Commercial TI projects). We have discontinued in-person inspections within occupied structures (*see exception below) and will attempt to complete as many inspections as possible via video/photo. We will provide inspections to work being done outside of the occupied structure (i.e. roofs, fences, detached garages, etc.) and will notify the property owner/contractor that we will not be holding face-to-face discussions with them during the inspection.  Our preference will be to complete those inspection via video/photo but will entertain in-person inspections where necessary as determined by the Field Inspection Supervisor.  We will also be wearing gloves and masks during the in-person inspection. 

The following is a list of what we believe could be inspected via video/photo in an occupied structure: caisson, footing, stem wall, water heater, furnace (without AC), drywall, final deck/ patio cover, driveway, and fence. Roofs can be done with drone.

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

Please note that we are evaluating our policies and procedures daily and these are subject to change.

Thank you for your understanding.

Updated: 4/03/2020 1:48 pm

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.

An inspector shall, based on that inspector's familiarity with the installer, require each individual doing electrical or plumbing work as defined by 12-23-101 definitions or 12-58-102 definitions C.R.S. respectively, to produce documentation showing they are a currently licensed Colorado state electrician/plumber or a registered apprentice. 

2018 International Codes and 2017 National Electric Code Adopted

Effective September 16, 2019





Notice to contractors and homeowners: your inspection may be performed by an unmanned aerial vehicle (UAV) commonly known as a Drone.  The inspection will be videotaped for review and will be attached to the permit record.

Schedule your inspections online through our CityView Portal. You 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. Inspections scheduled between 7:00 AM and 7:00 PM will occur the following business day.  

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

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.
  • Homeowners doing their own work can get a 2-hour window by calling 303-538-7250 between 8 AM and 8:30 AM on the morning of your inspection.
  • An adult at least 18 years of age shall be present for all required interior inspections.
  • Consultation inspections are available to any permit holder. Simply schedule it as you would any other inspection.

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/ReRoofing 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 10-22-18

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 20  - Working days or less
  • Tenant Improvements & Remodels - 10 working days or less
  • New Residential - 15 working days or less
  • Residential Remodel - 7 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