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, Shrewsbury Township administers the code through a third-party agency: Section 5-101 of the Township Code (Ord. 2004-01, April 7, 2004) says "Shrewsbury Township hereby elects to adopt, administer and enforce the provisions of the Pennsylvania Construction Code Act," the Township's residential permit application names Dependable Construction Code Services as its "Building Contact" at 717-759-5906 and the Township as its zoning contact, and the agency's own site lists Shrewsbury Township among the municipalities contracted with it "for all code disciplines of both non-residential and residential plan review and inspections." Section 5-102 adopts the Uniform Construction Code "as amended from time to time" by reference as the municipal building code, and Chapter 5 changes nothing in the code's roofing provisions. The Township's pages and its permit application name no code edition.
Permit process
Shrewsbury Township's code and pages read for this record do not say whether a house reroof needs a permit. Section 5-102 adopts the Uniform Construction Code, 34 Pa. Code Chapters 401 to 405, "as amended from time to time," by reference as the municipal building code, and Chapter 5 adds no permit clause of its own and names no roof work. Section 5-105 keeps in force building code ordinances adopted on or before July 1, 1999 "which equal or exceed the requirements of the code"; the Township Code prints no such ordinance. Section 27-1806 of the Zoning Ordinance requires a building permit and a zoning permit before a building or structure is "erected, moved, placed, constructed, or enlarged" and names no roof work. The Township's pages say nothing on reroofs. Its Application for Residential Building Permit and/or Zoning Permit offers "Roofing" among the boxes under both "Zoning Proposed work" and "Building Code Proposed Work," beside New Construction, Addition, Alteration, Demolition and Repair/Replace, and says "PERMIT MUST BE APPROVED, PERMIT ISSUED, AND POSTED ON THE JOB SITE PRIOR TO BEGINNING WORK!" The Township's 2026 fee resolution (Resolution 2026-05, January 5, 2026), read in full from its scanned pages, has no roofing line and prices building work done by the agency by an "Exhibit 1" that is not part of the published copy. The agency's own Building Permits: Do I need one? page names no roof work either way. 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 the Township requires a permit for a house reroof; ask the Township office (717-235-3011) or the agency (717-759-5906) before starting. The application says residential permits "may take up to 15 Business days for approval" and asks for a certificate of insurance "listing the applicable municipality as certificate holder," and the fee resolution sets a $250.00 nonrefundable residential building permit application deposit. The office is open Monday to Thursday, 8 a.m. to 4 p.m., and Friday, 8 a.m. to noon. Read for this answer: Chapter 5 of the Township Code, Construction Code (Sections 5-101 to 5-207), Chapter 4, Buildings, and Part 18 of Chapter 27, Zoning (Administration), in full; every page of a search of the whole Township Code for "roof" and for "reroofing," which found no permit provision naming roof work; the Township's Building Permits page; the residential permit application; the 2026 fee resolution; and the agency's home and residents pages.