Navigating the KCMO Building Code: A Guide for Homeowners

Understanding the specific mandates of the City of Kansas City, Missouri Planning and Development Department.

In Kansas City, Missouri, roofing is governed by the 2018 International Residential Code (IRC), but with several local amendments that make our requirements distinct from the suburbs in Johnson County or even neighboring Independence. Whether you are maintaining a historic shirtwaist home in Brookside or a newer build in the Northland, the code is the "law of the land" that ensures your home can withstand our volatile Midwestern weather patterns.

The Permit Mandate

KCMO requires a building permit for all roof replacements. Unlike some jurisdictions that allow a "repair" loophole, if you are stripping the shingles and replacing the underlayment, you must visit or call the 5th floor of City Hall at 414 E. 12th St.

  • Cost: Permits are generally based on the valuation of the work. For a standard $12,000 to $18,000 roof, expect a permit fee ranging from $150 to $275.
  • Liability: If your contractor fails to pull a permit, the city can halt work mid-project, or worse, require you to remove the roof for inspection later.

Local Amendments: The "Ice Barrier" Rule

One of the most critical aspects of the KCMO code (Section R905.1.2) involves the ice barrier. Because Kansas City is located in a region prone to "ice damming"—where melting snow refreezes at the eaves—the city mandates a self-adhering polymer-modified bitumen sheet (commonly called "Ice and Water Shield").

In KCMO, this barrier must extend from the lowest edges of all roof surfaces to a point at least 24 inches inside the exterior wall line. This is often more than a single 3-foot roll of material, especially on homes with deep overhangs found in the Waldo or Armour Hills neighborhoods.

Drip Edge Requirements

Per Section R905.2.8.5, a drip edge is mandatory at both eaves and gables. It must overlap the underlayment at the rakes and be tucked under at the eaves. This is a common point of failure in inspections for older homes near Troost Lake where original builds lacked this detail.

Shingle Fastening

KCMO follows the high-wind fastening schedule. While the code allows for 4 nails per shingle in some areas, local best practice and manufacturer warranties (like those from ABC Supply Co. on Manchester Trafficway) often necessitate a 6-nail pattern to combat the gusts that roll across the Missouri River valley.

The "Two-Layer" Myth

A frequent question from KCMO homeowners concerns "re-roofing" over existing shingles. Section R908.3.1.1 of the 2018 IRC technically allows up to two layers of asphalt shingles. However, there are massive caveats for KC residents:

  1. If the existing roof is water-soaked or has structural damage, you cannot overlay.
  2. If the existing roof is wood shake, slate, or clay tile, you must strip it completely.
  3. If the roof has already been recovered once, a full "tear-off" is mandatory.

Expert Note: In neighborhoods like Pendleton Heights, many historic homes still have original cedar shakes beneath multiple layers of asphalt. If your contractor finds wood shakes during a tear-off, the code requires the installation of solid sheathing (OSB or plywood) before new shingles can be applied.

Ventilation and "The 1/300 Rule"

KCMO inspectors are increasingly strict about attic ventilation. The code requires 1 square foot of net free ventilating area for every 300 square feet of attic floor space. In a standard Midtown bungalow, this usually means a balanced system of intake (soffit vents) and exhaust (ridge vents or "turtle" vents).

If a roof is installed without meeting these ventilation minimums, the shingles can reach temperatures exceeding 160°F in a Kansas City July, effectively "cooking" the asphalt and voiding the manufacturer warranty.