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, the Borough of Plum administers the code itself: its residential permit packet says "In 2004 the Borough of Plum elected to administer and enforce the provisions of the Pennsylvania Construction Code Act, Act 45 of 1999" and "Borough of Plum reviews the submission for UCC and Borough Ordinance compliance," its Building and Code Enforcement page says "Plum Boro enforces the Uniform Construction Code (UCC)," and its fee ordinance, Ordinance 982-24, prices building permits on a "Bureau Veritas fee schedule" and says "Bureau Veritas North America, Inc. reserves the right to charge below these minimum charges if deemed appropriate." The Borough publishes no codified ordinances online, and its Uniform Construction Code ordinance and any amendment to it were not located for this record. The Borough's pages and permit packet read for this record name no code edition.
Permit process
The Borough of Plum lists alterations and repairs as building permit work but has published nothing read for this record that names house reroofing as permit work or as exempt. The Borough's 2024 residential permit packet (read October 6, 2026) lists under "Building Permits are required for:" new dwellings, additions, "Alterations/Repairs," decks, "Porches/Porch Roofs" and other work, and names no reroofing permit or exemption; its Building and Code Enforcement and Applications pages name none either. Section 1 of Ordinance 982-24 (enacted July 8, 2024), the Borough's fee schedule, says "A permit must be issued by the Code Official prior to:" a list beginning "Constructing or altering a structure"; its renovation fee schedule "includes decks, porches, signs, repairs, and projects including plumbing, electrical, mechanical and fire protection" at $75 for the first $1,000 of work and $11 for each $1,000 after; and its only roofing line is "Commercial Roofing Inspections." This record does not decide whether a house reroof is altering a structure in that list. The Borough publishes no codified ordinances online, and its Uniform Construction Code ordinance and any amendment to it were not located for this record. The Department of Labor and Industry's register of municipal code change ordinances lists a Plum Borough proposal to require a permit for "All alterations or repairs to residential buildings which are exempt from the UCC by Act 92 of 2004," keeping exempt, among other work, "Re-roofing of less than 25% of total area"; the register shows it "Under review by L&I as of 9 / 30 / 2015" with a public meeting on November 2, 2015, and records no approval letter or enactment. No Borough ordinance with that text was located. 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 therefore does not state whether a Borough ordinance requires a permit for a reroof. Where a permit is needed, the application goes to the Borough with drawings, proof of workers' compensation insurance or an affidavit of exemption and a stamped survey; the Borough sets the fee after review, and inspections are booked at 412-795-6800 ext. 4504 with 48 hours' notice ("All inspections require a 48 hour notice"); the packet gives office hours of Monday to Thursday, 8:00 am to 5:00 pm, and Friday, 8:00 am to 4:00 pm. Read for this answer: the Borough's Building and Code Enforcement, Applications and Planning and Zoning Ordinances pages; its 2024 residential permit packet; Ordinance 982-24 in full; and the Department of Labor and Industry's register entry for the Borough.