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, McSherrystown Borough takes its permit paperwork at the Borough Office, 338 Main Street, and its Document Center page has a section headed "PA Municipal Code Alliance" that says "PA Municipal Code Alliance offers guidance in the process of applying for a Uniform Construction Code Permit"; Pennsylvania Municipal Code Alliance, Inc. (PMCA) lists an Adams Office at 1895B York Road, Gettysburg. The Borough's own Uniform Construction Code ordinance is not published on its website, whose Plans & Ordinances page lists Chapters 215, 190, 187, 107 and 182 and other chapters but no building chapter, or in the online code libraries of General Code (eCode360), American Legal Publishing, Municode or Code Publishing, so it was not read for this record, and no Borough ordinance reaching residential reroofing was read other than the zoning chapter quoted below. The Borough's pages name no code edition; PMCA's ice barrier sheet says "All Municipalities Served by PMCA follow and enforce the provisions of the 2018 International Residential Code (IRC)," and this record has not read the 2018 edition's text and does not decide which edition PMCA applies.
Permit process
McSherrystown Borough's pages and code read for this record do not say whether a house reroof needs a permit. Section 215-107 of the Borough's zoning chapter (Chapter 215, as amended October 13, 2004) says "A zoning permit shall be obtained from the Zoning Officer for the construction, development, enlargement, alteration, relocation, or conversion of any building or structure in accordance with the provisions of this chapter." It names no roof work and no repair, and this record does not decide whether a house reroof is an "alteration." The Borough's Document Center page links to PMCA's Frequently Asked Questions page, which answers its question "I am re-roofing my residential structure - do I need a building permit?" with a letter dated July 20, 2018 and addressed "Dear Municipal Official," which names no municipality and says "a residential Re-roof still requires compliance with the provisions of the UCC but does not require a building permit"; PMCA's Re-Roof Application Packet says "A Building Permit is required if there is a structural repair." Neither the Borough's pages nor PMCA's pages read name the Borough in connection with that letter. 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." This record does not state whether a permit is required for a house reroof in McSherrystown Borough; ask the Borough Office at 717-688-9284, the direct line its Borough Officials page gives for the Borough Manager and Secretary/Treasurer, and PMCA's Adams Office at 717-321-9046 before starting. The Borough Office is open Monday to Thursday, 9am to 2pm, and closed Friday. Read for this answer: the Borough's home, Document Center, Plans & Ordinances and Borough Officials pages; Chapter 215, Zoning, in full (a scanned file, read from the rendered page images); Chapter 107, Floodplain Management, and Chapter 135, Nuisances, which name no permit for roof work (also scanned); the Borough's swimming pool regulations; and PMCA's Locations, FAQ and Permit Applications pages, its re-roof letter, Re-Roof Application Packet and ice barrier sheet. The Borough's Uniform Construction Code ordinance and any building permit fee schedule were not found published and were not read.