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, Souderton Borough takes building permit applications at the Borough office, 31 West Summit Street, and Chapter 270 of the Borough Code says "This municipality hereby elects to administer and enforce the provisions of the Pennsylvania Construction Code Act." Section 270-2 adopts the Uniform Construction Code "as amended from time to time" as the municipal building code and fills in the local blanks of the codes it names, including Table R301.2(1); Chapter 270 changes nothing in the code's roofing provisions. Chapter 270, as amended in 2024, still names the International Residential Code 2018 and the other 2018 codes in filling in their local blanks, and the Borough's permit pages and application name no edition; this record has not read the 2018 edition's text and does not decide which edition the Borough applies.
Permit process
Souderton Borough's permit page says "In the file below, you will find the permit applications are needed for any work being done in Souderton Borough," without naming roof work. Chapter 270 of the Borough Code, Construction Codes, Uniform (Ord. No. 645, 2004, amended by Ord. No. 805, 2024), adopts the Uniform Construction Code by reference and names no roof work either way; its only permit requirement is the one the Uniform Construction Code itself carries. Section 1502 of the Borough's Zoning Ordinance says "No building shall be constructed or altered in the borough or the use of any building changed, nor vacant land occupied until a building permit is secured from the Zoning Officer"; it names no roof work. The Borough's Building/Repair Permits page (read October 9, 2026) says "In the file below, you will find the permit applications are needed for any work being done in Souderton Borough" and "No work is to start on jobs until you have an approved permit in hand," and names no roof work. The Borough's Application for Building Permit lists no roofing category, and its 2026 fee schedule (Resolution 2025-13) has no roofing line; its building permit fees include "Residential Addition or Alterations." 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." The fee schedule says "Any person who commences work before obtaining the necessary permits shall be subject to 100% of the usual permit fee in addition to the required permit fees." The Borough office takes applications by email, fax, mail or in person at 31 West Summit Street, Souderton, and says "For questions on what is needed for a permit, please call the Borough office at 215-723-4371"; it is open Monday to Friday, 8:30 a.m. to 5:00 p.m. Read for this answer: Chapter 270 of the Borough Code, Construction Codes, Uniform, in full; every page of a search of the whole Borough Code for "roof" and for "reroofing"; Article XV of the Zoning Ordinance on building permits, from the Borough's published copy (the codified Chapter 600 refers to it); the Building/Repair Permits page; the Application for Building Permit; and the 2026 fee schedule, Resolution 2025-13, a scanned document read from its page images.