What is Roof Sheathing?

Why Every Roof Component Matters When Replacing Your Roof – Part 1

Ever have a roofer stop by? After pointing to a few things, they usually start speaking another language. Flashing, drip edge… and what is roof sheathing?

Some shady roofers want to keep you in the dark. They say words you don’t understand and won’t explain how their “deal” will hurt the longevity of your roof. Cutting corners will cut your quote, but is it worth it?

Reliable roofers know all of your roof components are important and should be replaced so they all work together to protect your home. That’s the only way you’ll get a full life out of your roof.

We all know shingles. That’s the recognizable component. But if you only replace the top layer, you are setting yourself up for bigger problems down the road. You don’t have to be a roofing expert, but if you don’t know about the underlayment, or drip edge, or what is roof sheathing then shifty roofers may take advantage of you.

In the next few blog posts we’ll break it down. Let’s define what is roof sheathing, mention the different roof system components, why they matter, and why replacing all of them (not just the visible parts) is the smartest investment you can make.

Your Roof Is a System, Not a Single Part.

Think of your roof like your car. If your tires are bald, you don’t just replace one—you get a set, right? And if your brakes are shot, you wouldn’t only replace the left one. The whole system works together. If one piece fails, it can affect everything else.

Your roof is the same. It’s a complete system designed to keep water out, ventilate your attic, manage airflow, and protect your structure from Louisiana’s intense weather.

Replacing only one layer—like shingles—without addressing the full system is like slapping a new coat of paint on a rusted car and calling it “fixed.”

What is Roof Sheathing? / Other Key Roof System Components (And Why They Matter)

Here’s what actually makes up your roof system:

1. What is Roof Sheathing? (Decking)

This is the foundation of your roof—usually made of plywood or OSB. There’s also tongue and grove decking, which offers a different set of challenges. If you have any leaks, over time, your decking becomes soft, rotten, or moldy. Replacing shingles without checking your decking is like building on a cracked foundation.

It is IMPOSSIBLE to see areas of rot or damage if your decking is covered by roofing material. That’s why Roofing Louisiana always strips your roof to the decking. Not tearing to the decking is one way you get a cheaper price, but it’s a risky move if you care about your roof’s performance.

Roof sheathing or decking doesn’t always need to be replaced, but good roofers strip to this level to make sure. BY THE WAY… all shingle manufacturers recommend it. What does that mean?

Whether knowingly or not, many roofers will potentially void your warranty by not stripping your roof to the decking. Manufacturers have minimum requirements for your roof’s plywood or OSB. Normal decking is 1/2″, but many homes have 3/8″ decking. This needs to be evaluated and approved to accept the new roofing materials.

We don’t recommend tongue and groove decking. It is impossible to avoid nailing into the “groove” areas, which will cause the nails to back out over time. This, of course, will cause leaks. Many roofers will tell you that leaving the felt or underlayment will prevent this, yet take a moment to think about this. There are 40,000 nails on an average roof, which means 40,000 holes in the old underlayment. What kind of protection will you really get with that Swiss cheese? But more on that in a future blog post.

Now that you know what is roof sheathing and why it is important, let’s touch on the other parts of your roof system that we will explain in future blog posts.

5. Drip Edge

This small piece of metal at the edges of your roof directs water into your gutters and away from your fascia and foundation.

6. Water Shield (Optional but Recommended)

For added protection, this membrane helps prevent leaks in vulnerable spots like valleys or roof edges.

7. Shingles

This is the visible part—what most people think is the entire roof.

Why Replacing the Whole System Matters?

Here’s the big takeaway: your roof is only as strong as its weakest component.

Imagine spending thousands on new shingles… only to have a leak a year later because the underlayment wasn’t replaced. Or you upgraded to premium shingles, only to discover the warranty is invalidated due to improper installation (i.e. old flashing) Or watching your energy bills skyrocket because your old attic vents weren’t updated.

It’s frustrating—and expensive.

When you replace your entire roof system, you:

• Extend the life of your roof

• Get stronger protection from storms and moisture

• Improve your home’s energy efficiency

• Increase your home’s resale value

• Qualify for better manufacturer warranties

A full system replacement is a bigger investment up front, but it pays off in fewer repairs, longer lifespan, and peace of mind.

Don’t Just Fix a Roof—Upgrade It. At Roofing Louisiana, we believe your home deserves more than a quick patch or a cosmetic fix. You deserve a system that works together to protect what matters most—your family, your investment, and your peace of mind. And, we’ll answer your questions like, “What is roof sheathing?”

Every roof replace, we strip to the decking to make sure we build on a solid foundation. We believe in offer each customer the Red Carpet Experience, meaning we’ll happily explain what is roof sheathing… We walk you through every component, explain what we’re doing, and make sure your new roof isn’t just new—it’s smarter, stronger, and ready to handle anything Louisiana throws at it.

Ready to talk about upgrading your full roof system?

Let’s schedule a free inspection (or fill out a form) and walk through the roof system together. We’ll show you exactly what your current system is doing—and what it could be doing better. And at Roofing Louisiana, you know that we stand by our work and we’re not leaving town.

Now you can answer, “What is roof sheathing?” Don’t forget to read the following posts for more insight about the different parts of a quality roof system.