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Permitting Authorities / Missouri / Platte County - Planning & Zoning Department (Building Department)

Do you need a permit to replace a roof in Platte County, MO?

Adopted code

Platte County - Planning & Zoning Department (Building Department)

The Platte County Planning & Zoning Department, whose building section issues building permits for one- and two-family dwellings, works from the Platte County Administration Building on Third Street in Platte City. The county has adopted the 2018 International Residential Code, as amended. This listing covers unincorporated Platte County; cities in the county run their own permit offices.

Roof code checklist: Platte County, MO

ItemAnswerCode citeSourceVerified
Permit to replace a roofNot published
Repair permit thresholdNot published
Layer limit / roof-overPublishedR908.3.1.1International Residential Code.pdf2026-10-17
Deck & sheathingNot published
Drip edgeNot published
Ice & water shieldYesInternational Residential Code.pdf2026-10-17
Mid-roof inspectionNot published
Impact-resistant (Class 4) roofingNot published
Wind design criteriaPublishedInternational Residential Code.pdf2026-10-17
Adopted codePublishedco.platte.mo.us2026-10-17
Contractor license / registrationNot published
Sales & use taxPublisheddor.mo.gov2026-10-17

Each row comes from the sourced record on this page; full wording is in the table below. "Not published" means no official source for that item was found when the record was last verified.

Jurisdiction
Platte County, Missouri
Jurisdiction type
county
Address
415 Third St., Room 016, Platte City, MO 64079
Contact
  • url: https://www.co.platte.mo.us/planning-and-zoning
  • phone: 816-858-3338
Adopted code
The county's Planning & Zoning page lists the "International Residential Code 2018 version (as amended)" among the "BUILDING AND SPECIALTY CODES ADOPTED BY PLATTE COUNTY, MISSOURI." County Commission Order No. 2019-CO-181, approved December 16, 2019, adopts "the 2018 Edition of the International Residential Code as the building code of Platte County, Missouri" and repeals the 2012 edition. Its amendment list was read in full. It deletes R105.2, work exempt from permit, moving that subject into the county zoning order, fills in Table R301.2(1), and amends R801.3, roof drainage, in Chapter 8. It amends nothing in Chapter 9, Roof Assemblies.
Ice & water shield
Required — The county's amended Table R301.2(1), in County Commission Order No. 2019-CO-181, enters YES under Ice Barrier Underlayment Required, so the 2018 International Residential Code's ice barrier provisions for shingle roofs apply in unincorporated Platte County. About ice & water barrier
Wind design criteria
The county's amended Table R301.2(1), in County Commission Order No. 2019-CO-181, enters a wind design speed of 115 mph with topographic effects No, a ground snow load of 20, seismic design category A, severe weathering, a 36-inch frost line depth, termite damage Yes, a winter design temperature of 6 degrees, an air freezing index of 92.7 and a mean annual temperature of 55 degrees F.
Roof layer limit / recover
Two layers maximum, on the 2018 International Residential Code. Platte County's local amendment list in County Commission Order No. 2019-CO-181, read in full, does not touch Section R908, Reroofing, and neither deletes nor excepts it. The base rule therefore applies: R908.3.1.1 bars a roof recover "Where the existing roof has two or more applications of any type of roof covering." One existing layer may be recovered with a new layer; a second existing layer means the roof must be torn off.
Sales & use tax
UNINCORPORATED 5.4750% SALES TAX AND 5.4750% USE TAX FOR PLATTE COUNTY (Missouri Department of Revenue jurisdiction code 00000-165-000, listed as "PLATTE COUNTY"), per the Department's Sales and Use Tax Rate Tables for October, November, December 2026 (updated 8/25/2026). The same table lists 2 other rows for parts of the county inside an ambulance, fire or other special district, with a sales tax rate of 5.9750%. For a roofer, the Department's Contractors Tax Matrix (effective 10-24-2022) defines a contractor as "Any person entering into an agreement to improve, repair, replace, erect or alter real property," and lists "Purchases of parts, materials, supplies, and chemicals purchased by contractors" as taxable. It says the "Missouri sales or Missouri consumer's use tax must be paid to the vendor or accrued and remitted directly to the Missouri Department of Revenue."

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Sources

Roofing questions: Platte County, MO

Is ice & water shield required in Platte County, MO?

Yes. The county's amended Table R301.2(1), in County Commission Order No. 2019-CO-181, enters YES under Ice Barrier Underlayment Required, so the 2018 International Residential Code's ice barrier provisions for shingle roofs apply in unincorporated Platte County.

Can you roof over an existing roof in Platte County, MO?

Two layers maximum, on the 2018 International Residential Code. Platte County's local amendment list in County Commission Order No. 2019-CO-181, read in full, does not touch Section R908, Reroofing, and neither deletes nor excepts it. The base rule therefore applies: R908.3.1.1 bars a roof recover "Where the existing roof has two or more applications of any type of roof covering." One existing layer may be recovered with a new layer; a second existing layer means the roof must be torn off.

What building code does Platte County, MO use?

The county's Planning & Zoning page lists the "International Residential Code 2018 version (as amended)" among the "BUILDING AND SPECIALTY CODES ADOPTED BY PLATTE COUNTY, MISSOURI." County Commission Order No. 2019-CO-181, approved December 16, 2019, adopts "the 2018 Edition of the International Residential Code as the building code of Platte County, Missouri" and repeals the 2012 edition. Its amendment list was read in full. It deletes R105.2, work exempt from permit, moving that subject into the county zoning order, fills in Table R301.2(1), and amends R801.3, roof drainage, in Chapter 8. It amends nothing in Chapter 9, Roof Assemblies.