When most homeowners think about a new roof, they think about shingles. But the truth is, the real strength of your roof starts underneath—with the framing and the decking.
If those aren’t right, it doesn’t matter how good the shingles are. Your roof will fail early, warranties can be voided, and insurance can push back on coverage.
Let’s break it down in a way that actually makes sense.
Rafter Span and Spacing: The Foundation
Your rafters are what hold the entire roof system up. They’re designed based on span (how far they run) and spacing.
Most homes are built with rafters spaced:
- 16 inches on center
- or 24 inches on center
Here’s the key: the wider the spacing, the more load your roof decking has to handle.
That’s where problems start if the decking isn’t thick enough.
Roof Decking Thickness: Where Most Issues Happen
This is one of the biggest things I see missed on insurance scopes and cheaper installs.
Typical decking includes OSB or plywood, and thickness matters:
- 7/16” OSB → bare minimum in many cases
- 1/2” plywood → common on 16” spacing
- 5/8” plywood or OSB → standard for 24” spacing and stronger builds
If your home has 24” spacing and thin decking, you can get:
- Sagging between rafters
- Nail pops
- Shingles not sealing properly
- Premature roof failure
Bottom line: thinner decking might pass a basic install, but it won’t hold up long term.
Plywood vs OSB: What’s Better?
Both materials are widely used, but they behave differently.
OSB:
- More affordable
- Meets most minimum requirements
Plywood:
- Stronger in real-world conditions
- Handles moisture better
- Less likely to swell or break down over time
On many jobs—especially insurance work—we upgrade to stronger decking because it protects the entire system.
Manufacturer Specifications: This Is the Big One
Here’s what most people don’t realize:
Building code is not the final authority—manufacturer specifications are.
Every shingle manufacturer requires:
- A solid nailing surface
- Proper decking thickness
- Limited gaps in the decking
For example, if you have plank decking with gaps over 1/8”, manufacturers require:
- Full redecking, or
- A solid overlay
If that’s not done:
- The warranty can be void
- Insurance can deny future claims
- The roof can fail early
There’s no cutting corners here.
Why This Matters for Insurance Claims
This is where experience matters.
If your roof decking:
- Is too thin
- Has gaps
- Doesn’t meet current code
- Doesn’t meet manufacturer specs
Then you may be entitled to:
- Decking replacement
- Code upgrades (Law & Ordinance coverage)
- Additional supplements on your claim
Most homeowners never get this addressed because it’s not explained to them.
Real Talk
A roof is only as strong as what it’s nailed to.
If the structure and decking aren’t right, everything on top is just a temporary fix.
At 4th Perry LLC, we don’t just replace roofs—we make sure they’re built correctly from the foundation up, documented properly, and approved the right way through insurance when applicable.
Final Takeaway
A proper roofing system requires:
- Correct rafter spacing and load support
- Proper decking thickness (5/8” is the standard for strength)
- Full compliance with manufacturer specifications
Anything less is cutting corners—and that always shows up later.
Need an Inspection?
If you’re in Columbus, Ohio and want to know if your roof is truly built right, we offer free inspections.
We’ll check everything—from the decking to the structure—and give you a straight answer.
4th Perry LLC
Roofing • Siding • Gutters
📞 614-508-3181
4TH PERRY LLC Roofing • Siding • Gutters 
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