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, Glassport Borough's Building Inspector page says "Glassport Borough's Building Inspector is CEA" (CEA Code Enforcement Agency, 1633 Route 51, Jefferson Hills) and that "All projects and inspections stop and start with the Borough": forms and payments go to the Borough office at 12 Monongahela Avenue, and "CEA will not process forms sent directly to them." Section 5-101 of the Borough Code says "This Borough hereby elects to administer and enforce the provisions of the Pennsylvania Construction Code Act." Part 1 of Chapter 5 of the Borough Code (Ord. 1059, 2004) adopts the Uniform Construction Code "as amended from time to time" by reference as the municipal building code and adds no permit clause of its own; 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," and the codified Chapter 4, Buildings, holds only the building numbering rules. Section 5-106 says fees "shall be established by the governing body by resolution from time to time"; no fee resolution is posted on the Borough's site. The building permit application posted on the Borough's page says "2021 International Residential Code (IRC) requires detailed descriptions of the project"; no Borough page names any other edition.
Permit process
Glassport Borough's pages read for this record do not say whether a house reroof needs a permit. Part 1 of Chapter 5 of the Borough Code (Ord. 1059, 2004) adopts the Uniform Construction Code "as amended from time to time" by reference as the municipal building code and adds no permit clause of its own; 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," and the codified Chapter 4, Buildings, holds only the building numbering rules. Section 5-106 says fees "shall be established by the governing body by resolution from time to time"; no fee resolution is posted on the Borough's site. The PA UCC Building Permit Application posted on the Borough's Building Inspector page lists new construction, addition, demolition, PV / solar, shed, pool, deck, fence and other as the kinds of work and has no roofing entry, and no Borough page names a house reroof either as permit work or as exempt. The zoning chapter's zoning permit section, 27-1901, says "No such zoning permit shall be required in case of normal maintenance activities, minor repairs, and alterations which do not structurally change a building or structure"; that sentence speaks to the zoning permit only. 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 Borough requires a permit for a house reroof; ask the Borough office (412-672-7400) before starting. The Borough office is open Monday through Thursday, 8:00 a.m. to 4:00 p.m. Read for this answer: the Borough's home, Building Inspector and Forms and Permits pages; the PA UCC Building Permit Application posted there; and, from the Borough Code the Borough posts by chapter, Chapter 4, Buildings, Chapter 5, Code Enforcement, Chapter 8, Floodplains, Chapter 13, Licenses, Permits and General Business Regulations, and Chapter 27, Zoning, each read for every mention of roofs and permits.