Adopted building code
The 2021 International Residential Code, as adopted by the State in the Pennsylvania Uniform Construction Code (UCC). 34 Pa. Code 403.21(a)(7) adopts "The 'International Residential Code of 2021,' except that:" followed by the State's list of exclusions and modifications, effective January 1, 2026 (55 Pa.B. 7701). None of the State's changes touches Chapter 9, Roof Assemblies, or Section R803, Roof Sheathing, so those apply as the International Code Council publishes them. Work on existing buildings is also pointed to the State's existing-building code: "The repair, alteration, change of occupancy, addition and relocation of existing buildings must comply with Chapter 34 of the 'International Building Code of 2021' or with the 'International Existing Building Code of 2021'" (34 Pa. Code 403.21(f)). The UCC is the minimum everywhere in the state: "no municipality may propose or enact any ordinance which is less than the minimum requirement of the Uniform Construction Code" (Pennsylvania Construction Code Act, Act 45 of 1999, section 503(b)). The Act also lists work it "shall not apply to", including "Alterations to residential buildings which do not make structural changes or changes to means of egress" or to "Repairs to residential buildings," in each case "except as might be required by ordinances" kept in force under section 303(b)(1) or adopted under section 503 (Act 45 section 104(b)(5) and (6); 34 Pa. Code 403.1(b)(8) and (9)). The Act defines a repair as "The reconstruction or renewal of any part of an existing building for the purpose of its maintenance." So whether the code's roofing rules reach a given house reroof depends on the municipality's own ordinances. Everything above is Pennsylvania state law, the same in every municipality. Locally, Penn Township's Codes Enforcement page lists a Codes Enforcement Officer/Operations Coordinator (717-363-3674) and its UCC Board of Appeals page lists a Uniform Construction Code Board of Appeals; its 2026 fee resolution says "Building Permit fees will be in accordance with the fee schedule of the Township’s Third party inspection agency" without naming the agency; and its Permits & Applications page posts a Building Permit application and a brochure from Building Inspection Underwriters of Pennsylvania, Inc., 25 East McClure Street, New Bloomfield (717-582-4483). The Township office is at 100 Municipal Building Rd., Duncannon (717-834-5281). The Township's pages name no code edition, and no Township ordinance adopting the Uniform Construction Code was found on its site or read for this record.
Permit process
Penn Township's pages read for this record do not say in the Township's own words whether a house reroof needs a permit. The Township's Permits & Applications page (read October 10, 2026) lists a "Building Permit (Also Demolition)," says "A Zoning Permit is required when any new structure is put on a property, or use of the property is changed," and says "When in doubt, please call us to ask!" It links, as "CLICK HERE TO SEE MORE HELPFUL INFO ON BUILDING PERMITS," a brochure from Building Inspection Underwriters of Pennsylvania, Inc. (read from the rendered page images, as the file is a scan) that says "Building permits are required for the construction, enlargement, movement, change of egress, demolition or the change of occupancy of a residential building" and "Please contact your local Building Department or Building Code Official for help in determining if a permit is required before undertaking any home improvement projects since various exceptions may apply," and lists "Replacement/repair of existing roof" under "A permit is NOT required for the following items as long as the work does not violate a law or ordinance." The Township's Building Permit application, a general form for building and electrical work, lists "( ) Roofing - Total square feet" among its types of work. Article XVIII of the Township's Zoning Ordinance, Section 1802, says zoning permits are secured "prior to the issuance of a permit for the construction, erection or alteration of structure" and that no building or structure shall be "constructed, reconstructed, enlarged or restored, structurally altered or demolished without a building permit"; neither clause names roof work. The Township's Ordinances page posts only its Zoning Ordinance, and no Township building or Uniform Construction Code ordinance was found on its site. Under state law, Act 45 section 104(b)(5) and (6) list "Alterations to residential buildings which do not make structural changes or changes to means of egress" and "Repairs to residential buildings" among work the Act does not apply to, "except as might be required by ordinances in effect pursuant to section 303(b)(1) or adopted pursuant to section 503," and 34 Pa. Code 403.62(c) says "A permit is not required for the exceptions listed in § 403.1(b) (relating to scope) and the following, if the work does not violate a law or ordinance." Ask the Township office (717-834-5281) before starting; the Permits & Applications page says "If a structure is built without permits, state law allows the removal of the structure at the cost of the landowner." Read for this answer: the Township's Permits & Applications, Codes Enforcement, UCC Board of Appeals, Township Fees, Ordinances and Contact pages; its 2026 fee resolution and the later fee schedule it posts; its Building Permit application, General Permit Application and Zoning Permit application; the building permit brochure; and Article XVIII, Section 1802, of its Zoning Ordinance. The Township office is open 8:00am to 4:30pm, Monday through Friday.