Roof Sheathing Material 101: Here’s What You Need to Know

Workers building roof, preparing for roof sheathing material

Before people started using roof sheathing material, they constructed roofs with shingles and a layer of boards beneath them. Exterior grade plywood wasn’t available until the 1940s.

In fact, your house was probably built like that if built before 1970. Before sheathing, spaces between the boards caused leaks, and water damage was a huge issue. The beautiful thing about sheathing is that it creates a protective layer beneath the shingles. Decking, which is another word for sheathing, plays a vital role in supporting the structure of the rooftop. When elements like snow accumulate on the roof, the decking helps distribute some of the added weight.

Your roof is the one most essential components of your home. It’s what keeps you protected. The problem is, roof sheathing material isn’t visible so sometimes issues go unnoticed. By the time things get bad, the damages are severe and are more expensive to repair.

You don’t have to be an expert in these materials to learn all any homeowner needs to know. In fact, we’ve gathered up the facts you need, right here.

Why Roof Sheathing Material Is Important

A lot of roofs are layered with asphalt shingles, which are heavy. Each shingle weighs about 2.5 pounds, and the combination of all the shingles adds additional pressure. The decking is what provides support for the weight of the shingles. If you live in a coastal area, taking care of your roof is vital. As a matter of fact, sheathing loss is one of the most common structural failures in hurricanes.

As you know, severe weather can happen at any time. Falling trees, high gusts of wind, and hail are all threats to your home. Roof decking helps to barricade your house against such damages. Roof sheathing isn’t about remodeling and keeping your home looking modern. It plays an essential role in securing the safety of you and your family.

Also, sheathing can help stop the spread of fire because flame retardants are sprayed on most plywood and provide some resistance against fires. Additionally, the outer layer of your rooftop usually blocks additional moisture, but sheathing offers security against leaks.

The Different Types Of Decking Materials

Solar panel roof sheathing material with radiant barrier
Image CC0 by ulleo via Pixabay

Radiant barrier roof sheathing material

Radiant barrier roof sheathing is your best option for cutting down on your electric bill. The aluminum material acts as a barrier, which blocks 97 percent of radiant heat. As the temperature increases, the better the barrier works. As a result, your attic and home are cooler, which reduces your use of air conditioning. Radiant barrier sheathing is the most cost-effective roofing material.

Watch more about radiant barrier roof sheathing in this video:

Plywood roof sheathing

Plywood roof sheathing consists of multiple layers of thin wood which come in 4 x 8- foot sheets and the most commonly used grade is CDX. It’s sturdy and does an excellent job of holding nails in place. The thickness of plywood ranges from 1/4- inch to 1 inch. Generally, it should have a minimum thickness of 3/8 inches. Determining the size to use on your roof depends on your roof slope, the spacing of rafters, and the weight of any other materials put over the decking. After installing sheathing plywood, you should add tar paper and composite shingles.

Zip system roof sheathing material

Zip system roof sheathing material is a single-panel with multiple control layers built in. It’s combined with a water-resistant barrier and a strong wood panel. The built-in layer protects your roof from water intrusion, plus there is no need to add felt to your roofing with zip system sheathing. Eliminating this step saves time in the installation process and takes less effort.

OSB roof sheathing material

OSB, better known as Oriented Strand Board, is composed of layers of wood strands and water-resistant adhesives. It’s less expensive than plywood, and some believe it’s not as durable. However, the National Roofing Contractors Association and the Asphalt Roofing Manufacturers Association both recommend it. The benefit of using OSB is that it’s less likely to swell during changing moisture conditions. Unfortunately, too much moisture makes the wood rot but choosing oriented strand board with rot-resistant material reduces decay.

While OSB developed relatively recently, it became more popular than plywood in North America by 2000. Today, nearly twice as much OSB as plywood is produced in North America. Outside of North America, it is not a common use in construction. In 2005, Europe and Latin America produced 3.5 billion square feet of OSB. This was less than seven times what was produced in North America that year.

Watch this video on how OSB is made:

OSB Roof Sheathing Material vs. Plywood Roof Sheathing Material

The two most popular roof sheathing materials are OSB and plywood. Both of these are more economical than radiant barrier roof sheathing and zip system roof sheathing. Because of their affordability, most homeowners opt for one or the other. However, there is some debate as to which material is the best. The International Association of Certified Home Inspectors has compiled a list of facts about the two materials.

OSB and plywood both let off formaldehyde gas Ooff-gas formaldehyde, OSB off-gasses more of the carcinogenic gas.

Plywood floors are stiffer than OSB floors by a factor of approximately 10 percent with nails and screws more likely to remain inside of plywood.

OSB and plywood are both manufactured according to the same performance standards. Made from narrower, faster-growing trees, OSB is built into panels that are larger than plywood. Also, it is more uniform, so there are fewer soft spots, such as those that can occur in plywood.

While there are many differences between the two, the decision comes down to your preference. OSB panels are larger, which means you can buy fewer boards and save money. If expenses aren’t an issue for you, plywood might be your option. Both of them are different, yet each gets the job done.

Heavy snow on roof sheathing material
Image CC0, by jackmac34, via Pixabay

Beware of Rotted Roof Sheathing

It’s important to understand that rotted plywood is not durable. Not only is the wood weak, but it also doesn’t grip the nails firmly. Rotted lumber absorbs water quickly. This kind of problem will eventually cause leaks in your attic and ceilings. Putting new shingles on top of rotted wood can cause the roof to shift, so that’s not a good idea. Although the additional repair might be a bit of a headache, it’s best to fix the damages before problems worsen.

Watch how to replace damaged sheathing below:

Making the Best Decision for Your Home

Repairing your roof might be a pain, but it’s necessary. Although it’s an inconvenience there are some are preventative steps you can take to keep damage at bay.

Be sure to replace broken shingles and cut down any dead trees that could potentially fall on your roof. Also, keep in mind that depending on the circumstances, you might be able to file an insurance claim to pay the expenses. If you are eligible to use your home owner’s insurance, it probably won’t cover radiant barrier roof sheathing or zip system roof sheathing. Check with your insurance provider before making repairs.


Featured Image: CC0, by GregReese, via Pixabay


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