Thornton Colorado Roofing Codes

Denver roofing contractors reference the Thornton Colorado Roofing Codes for residential roof repair and replacement and commercial roof repair and replacement. The building code and energy codes are based on 2015 specifications.

Information Updated On

11/27/18

Building Department Phone

303-538-7250

Inspection Line

303-538-7396

Fax

303-538-7650

Department Website

http://www.cityofthornton.net/government/citydevelopment/Pages/building-inspection.aspx

Current Building Code

2015 IBC/IRC

Current Energy Code

2015 IECC

Requires a Building Permit

Yes

Roof System/Fire Rating required for Residential Dwellings

Class A

Roof System/Fire Rating required for Commercial Buildings

Class A

Roof System/Fire Rating required for Multi-Family

Class A

Special conditions

Roof class is dependent on construction type

Minimum sustained wind speed rating for Asphalt Shingles

90 mph 3 second gusts

ASTM Standard for wind rating

ASTM 3161

Requires a manufacturer’s wind warranty

Yes

Requires wind nailing

Yes

Inspectors carry ladders for the final

No

Requires midroof (in progress) inspection

Yes

Maximum number of layers of flat roof material permitted

2 if allowed by manufacturer

Require a sheathing/decking inspection

Yes when any portion of decking replaced

Requires solid sheeting (plywood/OSB) over spaced decking

Yes

Maximum gap size for sheeting

¼ inch gap

Requires drip edge

Yes

Drip edge size minimum

1×2 minimum ¼” below sheathing

Requires Rake/Gable metal edging

Yes

Enforces the use of Self Adhering Underlayment (i.e., Ice & Water)

No

Underlayment required for 4:12 and above

15#

Type of valleys allowed

Both

Valley Underlayment/Material required for closed valleys

Either – in accordance with installation instructions

Valley Underlayment/Material required for open valleys

Ice and water under metal

Kick-out required on Step Flashing

Yes

Minimum curb height requirement

No

Requires ridge cap

Yes

Requires ventilation to meet building codes

Yes

Permits Soffit eave/vents

Yes, new construction only

Allows 90 lb rolled roofing on low slope heating living space

Yes

Low Slope

1:12

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