COMMERCIAL BUILDINGS - All commercial buildings require a building permit to re-roof. Commercial projects that include the removal of roof insulation must replace the insulation with thicknesses that meet the current energy code. An energy code calculation is typically required and generally results in an increase in insulation thickness.
RESIDENTIAL BUILDINGS - One & two family dwellings do not require a permit to replace shingles only. Permits are required for re-roofing projects that include the repair or replacement of roof decking. All re-roofing projects, including those that do not require a building permit, must meet the provisions in Chapter 9 of the International Residential Code. Flashings (including kick-out flashings and drip edges) are required; however, ice barriers are not required. The installation of a new roof covering over a single layer of existing roof covering is permitted where the new roof covering is installed in accordance with the manufacturer's approved installation instructions. Roofs containing two or more layers of shingles must be completely removed before installing new shingles. Underlayment must also be replaced when re-shingling a roof. Asphalt shingles must be installed in accordance with the shingle manufacturer’s installation instructions on solidly sheathed decks without holes, cracks, rot and/or gaps (refer to 2018 IRC Sections R905.1 & R905.2). Roofs may not have two or more layers of decking unless approved by an engineer with support documentation. All citizens are encouraged to use roofing contractors who are registered with the city and are members of the North Texas Roofing Contractors Association. A searchable website is available at https://www.ntrca.com/
For additional information, please see the Owens-Corning Technical Bulletin for roof decking requirements at http://www.owenscorning.com/NetworkShare/Roofing/10022499-Roof-Deck-Requirements-Technical-Bulletin---TB-07.pdf