Updated : 04/22/2024

Overview

The City of Thornton has adopted the ICC 2021 building codes on February 14, 2023 and take effect on June 1st, 2023. 

Thornton, CO adopts the following codes:

• The International Building Code, 2021 edition, including Appendix I. Thornton, CO Muni. Code § 10-151 (adopted) with amendments at § 10-152.
• The International Residential Code, 2021 edition, including Appendices H and K. Thornton, CO Muni. Code § 10-164 (adopted) with amendments at § 10-165.
• The International Existing Building Code, 2021 edition. Thornton, CO Muni. Code § 10-176 (adopted) with amendments at § 10-177.
• The Uniform Code for the Abatement of Dangerous Buildings, 1997 edition. Thornton, CO Muni. Code § 10-159 (adopted) with amendments at § 10-159.1.

Helpful resources for Thornton, Colorado include the following.

• PLRB, Ordinance and Law Coverage Discussion for Colorado

Residential Building Code

Colorado has yet to adopt a statewide residential code. Local laws will control.See PLRB, Colorado Building Codes for more information on state level codes.

Thornton adopted the 2021 IRC, locally. Note that adoptions usually come with amendments. So, it is important to review those amendments in addition to the unamended model code.

You can find a copy of the model code here.

You can find information about amendments to the model code here.

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2021 IRC(Thornton, CO Sec. 10-164. - International Residential Code adopted by reference.)

...The International Residential Code, 2021 edition, published by the International Code Council, Inc. 500 New Jersey Avenue, NW, 6th Floor, Washington, D.C. 20001., is hereby adopted by this reference and incorporated in this Code as the Residential Code of the city. The purpose and subject matter of the International Residential Code includes...

Drip Edge

Drip Edge: yes

Ice Barrier

Are ice barriers required for Thornton ? No
Citation: Thornton, CO Muni. Code § 10-165.
Municipal Code https://www.thorntonco.gov/government/citydevelopment/Documents/development-services/building-inspection/amendments-to-2021-codes.pdf#page=27
Comments:

Table R301.2(1)
CLIMATIC AND GEOGRAPHIC DESIGN CRITERIA

Ground Snow Load	Wind Design		Seismic Design Category f	Subject To Damage From			Winter Design Temp e	Ice Barrier Underlayment Required h	Flood Hazards g	Air Freezing Index i	Mean Annual Temp j
	Speed d (mph)	Topographic effects/Special Wind Region/Windbourne debris zone		Weathering a	Frost line depth b	Termite c
30 psf	See footnote p	No	B	Severe	30 in n	Slight to Mod	1°F	No	See footnote g	1500	45°F

Comments

Thornton, CO adopts the International Residential Code, 2021 edition, including Appendices H and K. Thornton, CO Muni. Code § 10-164 (adopted) with amendments at § 10-165.

Existing Buildings

Existing buildings, meaning buildings that were built in accordance to code at the time of construction, typically merit extra consideration in a current updated code.

There is no mention of the adoption of Appendix J of the 2021 IRC.

Commercial Building Code

Thornton adopted the 2021 IBC, locally. Note that adoptions usually come with amendments. So, it is important to review those amendments in addition to the unamended model code.

You can find a copy of the code here.You can find information about amendments to the model code here.

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See Muni. Code(Thornton, CO Sec. 2-55. - Adoption of codes by reference.)

...Charter reference— Adoption by reference, § 8.10. Cross reference— How Code designated and cited, § 1-1; Uniform Building Code adopted by reference, § 10-151; Uniform Plumbing Code adopted by reference, § 10-153; Uniform Mechanical Code adopted by reference, § 10-155; Uniform Sign Code adopted by reference, § 10-157; Uniform...

Comments

Thornton, CO adopts the International Building Code, 2021 edition, including Appendix I. Thornton, CO Muni. Code § 10-151 (adopted) with amendments at § 10-152.

Existing Buildings

Thornton, CO adopts the following codes:

• The International Existing Building Code, 2021 edition. Thornton, CO Muni. Code § 10-176 (adopted) with amendments at § 10-177.
• The Uniform Code for the Abatement of Dangerous Buildings, 1997 edition. Thornton, CO Muni. Code § 10-159 (adopted) with amendments at § 10-159.1.

Other Building Codes