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, or structural members like rafters or trusses.
What is the code on decking? Decking is per 2018 IRC Section R803 and Table R503.2.1.1(1)
Is drip edge required? Yes, if replacing decking per 2018 IRC Section R905.2.8.5
Ventilation requirements?Per 2018 IRC Section 806
All re-roofing projects, including those that do not require a building permit, must meet code provisions. Flashings and drip edges are required. Shingles must be completely removed before the installation of new shingles. Underlayment must also be replaced when re-shingling a roof.