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, Harmar Township administers the code through a contracted agency: its Building Inspection page (read October 10, 2026) says "the UCC is enforced by the Township's Third-Party Building Inspector," currently the Code Enforcement Agency (CEA), that the process "begins with a Zoning Permit Application" submitted to the Township at 701 Freeport Road, Cheswick, and that Township staff then send building permit applications to the agency, and the Township's 2026 fee resolution says "Harmar Township has contracted with Code Enforcement Agency" to administer and enforce the codes. Section 5-101 of the Township Code (Chapter 5, Part 1, Ord. 354, June 2, 2004, read October 10, 2026) says the Township "hereby elects to administer and enforce" the Pennsylvania Construction Code Act and Section 5-102 adopts the Uniform Construction Code as the Township's construction code. Part 1 names no roof work and adds no permit clause of its own for house repairs, and its Section 5-108 says "the more stringent code or ordinance shall apply" where Part 1 conflicts with another Township ordinance. Section 5-103 adopts "the 2003 editions" of the International Codes, the International Residential Code among them, while the Township's own Residential Building Application, a form posted on its Applications & Forms page, is headed "PA UCC Building Permit Application 2021 Code"; this record has not read the 2003 edition's text and does not decide which edition the Township applies to a house.
Permit process
Harmar Township's code and pages read for this record do not say whether a house reroof needs a permit. Section 5-101 of the Township Code (Chapter 5, Part 1, Ord. 354, June 2, 2004, read October 10, 2026) says the Township "hereby elects to administer and enforce" the Pennsylvania Construction Code Act and Section 5-102 adopts the Uniform Construction Code as the Township's construction code. Part 1 names no roof work and adds no permit clause of its own for house repairs, and its Section 5-108 says "the more stringent code or ordinance shall apply" where Part 1 conflicts with another Township ordinance. Section 27-1202 of the Township's Zoning chapter, headed Building Permits and issued by the Zoning Officer, says "No person, agency or business shall erect, move, structurally alter, remove, extend or convert any structure or building or any part thereof, nor change the use of any land until a building permit has been issued by the Zoning Officer" and "Permits shall not be required for painting, residing, masonry maintenance, interior renovations not involving structural changes, or for the installation of awnings or similar weather control devices"; it names no roof work, and this record does not decide whether a house reroof is a structural alteration under it. The Township's pages name no roofing rule. Its Building Inspection page says "Projects that typically only require a Zoning Permit include, but are not limited to, sheds, fences, and small signs," and its Zoning Permit Application has an official-use line "Needs a Building Permit." Resolution No. 16-2026, the Township's 2026 fee schedule, says "Projects that require a building permit include, but are not limited to, new construction, additions/alterations to existing buildings, demolitions," and lists "decks, porch roofs, and solar panel installations"; it does not name reroofing, and it attaches the agency's 2022 fee schedule, which has no roofing line. The agency's Residential Building Application, posted on the Township's site, names no roofing permit type. 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 (724-274-4550) before starting; its Building Inspection page says "Please do not send permit applications directly to CEA unless instructed by a Township Official to do so." Read for this answer: Chapter 5, Part 1 of the Township Code, Uniform Construction Code (Sections 5-101 to 5-109), in full; Chapter 27, Part 12, Administration (Sections 27-1201 to 27-1207), 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 Building Inspection, UCC Permits & Requirements, Applications & Forms and Zoning Permits & Applications pages; the agency's Residential Building Application; the Zoning Permit Application (a scanned form, read from its rendered page); and Resolution No. 16-2026 with the agency's fee schedule (scanned, transcribed from the rendered page images).