The Structural Backbone: A Kansas City Homeownerâs Guide to Roof Decking
In the Kansas City roofing industry, we spend a lot of time talking about shingles and aesthetics. However, the most critical component of your roofing system is the one you rarely see: the roof decking (or sheathing). This is the structural layer of woodâtypically OSB or plywoodâthat is nailed to your rafters. In our volatile Midwestern climate, where humidity can soar to 90% in July and snow loads can stress a structure in January, the integrity of your decking is what determines if your roof will last 30 years or fail in 10.
Local Material Standards: OSB vs. CDX Plywood
When walking through a new build in Overland Park or a renovation in Waldo, you will primarily see two materials used for sheathing. Understanding the difference is vital for KC homeowners, especially given our local temperature swings.
OSB (Oriented Strand Board)
The standard for most KC modern builds. It is engineered by compressing wood strands with adhesive. It is highly uniform and cost-effective. At local suppliers like McCray Lumber or ABC Supply, OSB is currently the go-to for volume roofing because it lacks the "voids" found in natural plywood.
CDX Plywood
Often preferred for high-end custom homes in Mission Hills or Hallbrook. Plywood handles moisture better; it swells uniformly and dries out quickly without the "edge-swell" that OSB can suffer from if exposed to the humid Kansas City spring rains during installation.
The "Plank Decking" Dilemma in Older Neighborhoods
If you own a home in Brookside, Pendleton Heights, or the Northeast KCMO district, your roof likely isn't built with sheets of wood. Instead, it likely utilizes 1x6 or 1x8 pine planks.
Modern asphalt shingles require a smooth, solid surface. Over time, these old planks warp, cup, and develop wide gaps (often exceeding 1/4 inch). Per the 2018 International Residential Code (IRC) adopted by KCMO and Olathe, shingles cannot be installed over gaps this large.
The Fix: In these neighborhoods, we frequently perform a "re-deck," where we install 7/16" OSB directly over the old planks to provide a stable, code-compliant nailing surface.
Kansas City Building Codes & Inspections
Most municipalities in the KC metro, including Leeâs Summit and Shawnee, strictly enforce sheathing thickness. For rafters spaced 24 inches apart, you typically must use at least 15/32" (effectively 1/2") thickness.
- H-Clips: In many Johnson County jurisdictions, code requires "H-clips" between sheets of OSB. These small metal clips allow the wood to expand and contract during our 100-degree summer days without buckling.
- Spacing: A 1/8-inch gap between sheet ends is required to prevent the "wavy" look you see on poorly installed roofs in cheaper developments.
- Fastening: Inspectors in Wyandotte County look for specific nailing patternsâusually 6 inches along the edges and 12 inches in the field.
Current Pricing Trends at KC Suppliers
Decking prices are the most volatile part of a roofing estimate. While local lumber yards like Schutte Lumber Company in the Crossroads offer high-quality CDX, prices fluctuate based on national demand.
| Material Type | Est. Price Per Sheet (Retail) | Common Application |
|---|---|---|
| 7/16" OSB | $16 - $22 | Standard residential replacement |
| 1/2" CDX Plywood | $32 - $45 | Luxury homes / High-moisture areas |
| Radiant Barrier OSB | $24 - $30 | Energy-efficient upgrades (TechShield) |
Note: Prices reflect average KC metro retail rates and fluctuate monthly based on the lumber market.
Warning Signs: When Decking Must Be Replaced
A quality Kansas City roofer will never shingle over rotten wood. During the "tear-off" phase, we specifically look for: