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What Thickness Osb For Roof

What Is The Best Thickness For Roof Sheathing

OSB vs. Plywood: Which Should You Choose for Your Roof Deck?

There are various opinions on this matter, but the most commonly touted thickness for roof sheathing on a shed is 5/8-inch thick. Anything less may result in eventual bowing or sagging between the rafters or trusses, especially if you are using OSB. Some people trust 1/2-inch of thickness for plywood, which is a little stronger than OSB.

The absolute minimum you can consider is a 3/8-inch thickness, but its certainly not recommended. In fact, this thickness will not satisfy building code requirements in most places.

If you live in an area prone to heavy snow, you may even want to use something thicker. Roof sheathing is not a place where you can afford to skimp. It will also allow you to replace broken or cracked shingles without worrying about having to replace part of the sheathing. Youll still have a solid place to attach the new shingles. You surely dont want to have to worry about your shed every time the weather forecast includes several inches of snow.

How Many Sheets Of Plywood Do You Need For A Roof

You can customize the plywood sheets if you want to purchase them in bulk. But your roof area is specific.

And the specified area needs a specific distribution of plywood. Lets assume your roof area is about 2400 square feet. And if you buy a 4 by 8 feet plywood sheet, it will cover 32 square feet of your roof.

Then if you do some quick math by dividing 2400 square feet of an area by the sheet area of 32 square feet, you get the number of sheets you need, which is 75 plywood sheets for your 2400 square feet roof area.

So, as per your roof area, you can get the number of plywood sheets you need.

Stay Robust Against Any Wild Wind:

Every area is unsafe due to the wild storms. Wild storms always have the wild wind with them. If you build a home with a thin layer of plywood, it will not stay firm against stormy winds.

Moreover, if somehow a tree falls on the rooftop, it may not hold the rooftop strongly. So, a robust plywood setup is required.

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What Type Of Plywood Is Used For Roof Sheathing

CDX is the most commonly used type of plywood for sheathing and is considered to be construction grade. The X indicates the type of glue used in the formation of the plywood. It makes the plywood resistant to water. This makes it far less likely to be damaged by water leaking underneath broken or cracked shingles. The C and D mean that one side of the panel is graded C, while the other side is graded as D.

One other type used is FRT, which stands for fire-retardant plywood. Its sometimes required on buildings in certain areas, such as those prone to wildfires. If your local building codes require this, it will be included on the list of regulations you can get when looking into getting a building permit. If you want to waterproof your plywood yourself get more information in my article Whats the Best Way to Waterproof Plywood?

What Are The Most Popular Types Of Roof Sheathing

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Roof sheathing is made of several materials. Such as:

  • OSB or Strand Board
  • Wood boards
  • Compressed wood panels
  • Despite that, the most popular ones on the market nowadays are OSB and Plywood, with dimensional lumber falling out of the competition because its significantly more costly without offering a true advantage over the much cheaper and easier to use alternatives.

    OSB is currently the most popular option for roof sheathing because its incredibly durable, all the while being relatively affordable. About 60 to 75% of all roof sheathings in North America are currently made of OSB.

    Plywood is also commonly used because its more durable and lighter in weight. It also dries up quicker than OSB and has a better moisture resistance in general.

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    What Should I Use For Roof Sheathing

    It is possible to use Oriented Strand Board or plywood, although plywood will have a higher pull-through resistance than OSB. You can use panels rated as Exposure 1 or better if you want to. The Engineered Wood Association recommends installing sheathing panels according to its recommendations. Panels should not be less than 4 feet long.

    Minimum Roof Sheathing Thickness

    Minimum sheathing requirements dictate that thick is the lowest you can go in terms of thickness.

    What happens if your roof sheathing materials are too thin?

    Wrong dimensions will lessen the integrity of the overall structure of your roof. Thin layers of roof covers are more prone to bend between the foundation, thus compromising the outer roof system. When additional weight is applied to a board, the panel will sink over time.

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    Provides Barrier To Roof Damage

    The sheath acts as the final form of barrier against elements and damage to the roofing material.

    Even when damage occurs to the roofing material, the roof sheath, in most cases, is solid and waterproof, so it will take a while before water and moisture penetrate the board. Hopefully, proper repairs will is carried out by then.

    How Much Does Roof Sheathing Cost

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    During roofing, roof sheathing is priced cumulatively with the rest of the roofing work. You cannot have one contractor lay down the skeleton and another layout the roofing material.

    But before the labor charge agreement, the roofing contractors will know which roof sheathing material to use.

    Wood, Concrete, and Steel are priced differently. But different wooden materials could be priced the same as they are made from the same material, have the exact measurements, and even the same thickness.

    The difference between the OSB and plywood costs around $50-$60, where OSB could cost $600 and plywood $660. It is the cost of installing 500 square feet of roof.

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    Can Oriented Strand Board Be Used For Roofing

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    Oriented strand board , an engineered wood panel, is an economical alternative to plywood. The two products are largely interchangeable, but OSB roof sheathing has a slightly lower tolerance for moisture. Manufacturers mitigate this with water-resistant treatments.

    Tip

    Oriented strand board is recommended for use as roof sheathing.

    Osb Vs Plywood Screw Holding

    Screwe holding ability is a critical matter in roofing. When the roofing material cannot hold nails and screws properly, of course, it cannot hold its shape very well. This is why you need to know the screw holding ability between plywood vs. OSB for roofing.

    The full information will be displayed down below so that you will know which one is better.

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    How Thick Should Plywood Be For Roofing

    Plywood is used for various purposes. It is widely used because of the lightweight and strongness of this material. Five to eight inches of plywood thickness is suggested. Any less than five inches in thickness is not a good choice for roofing. The roof takes the most pressure than any other place.

    The size of the plywood may differ according to different shedding types. Lets get to know about them.

    What Size Of Roofing Nails For Roof Sheathing

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    When installing sheathing, use 8d roofing nails. An 8d nail is 2.5 long and is more than enough to adequately fasten most thicknesses of roof substrate.

    If you opt to use screws, then #10 wood screws would work. Make sure they are 1.5 long, which would work for ½ thick panels. If your deck is thicker, then youd want #12 wood screws at 2 long.

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    Plywood Holds The Moisture Advantage Over Osb

    However, there is one area of concern in which plywood beats OSB. The biggest difference is how both react when exposed to large amounts of moisture over an extended period of time. Except on projects in very dry regions, , sheathing is often exposed to rain, snow, and ice during construction delays. When plywood gets wet, it tends to swell. However, it does so consistently across the sheet, and returns to normal dimensions as it dries out. Because Plywood dries out relatively quickly, the swelling is usually not enough to affect roof finishes. In this case, plywood has the edge.

    OSB takes longer than plywood to get saturated, but also takes much longer to dry out. When used as roof sheathing, this tendency to hold moisture means it will degrade faster than plywood when exposed to chronic leaks. Furthermore, when OSB gets wet, its edges tend to swell and stay swollen even after the panel has dried out. Swollen edges have been known to display as visible ridges called “ghost lines” through asphalt roof shingles. OSB manufacturers developed water-resistant edge seals to correct the problem, but the edge seal gets lost as panels frequently get cut on-site.

    What Type Of Osb Is Used For Roofing

    Half-inch OSB is suitable for rafter spacings up to 24 inches, whether or not the edges are supported. Sheets must have a 1/8-inch expansion gap between them and should be secured to the rafters with 8d nails. The nails should be spaced 6 inches around the edges of a sheet and 12 inches in the middle.

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    Benefits Of Roof Sheathing

    Roof sheathing helps distribute the weight of the entire roof evenly. Due to the sheathing boards attached to the roof system, it makes sure that heavy rain and snow do not cause sagging or bowing.

    Since most sheathing boards are weatherproofed, having roofing sheathing helps prolong the lifespan of the roof and is safe from water leaking.

    Asphalt shingles are commonly weatherproofing treatments and adding sheathing to this gives them an additional layer of protection.

    When a massive snowstorm or typhoon goes near your home, roof seething assures your roof of no sagging or bowing.

    Roof sheathing also has a fire-retardant treatment that helps prevent attic fires. Attic fires are prone to homes that are heat-insulated and exposed to extreme heat during the day.

    If a roof has also passed its time of prime, it will be prone to breakage and damage from environmental changes.

    For homeowners who opt to seldomly check up on their roof, roof sheathing will be a sustainable solution to secure the roof system in your home.

    Planning Your Roof With Osb

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    OSB bodies are for roof sheathing needs. OSB comes in 4×8 foot sheets, although the size is flexible. A board can be up to ¾-inch thick. The optimal thickness for your board should be dictated based on how well your roof looks.

    The nails used in getting these ready are essential to the layout as well. The nails have to be spaced at about six inches around their edges and twelve inches in the middle. The placement ensures enough coverage around all parts of the body.

    We at Town and Country Roofing can help you with all the needs you have for your roof. We can serve your sheathing needs, particularly when you require oriented strand boards around your roof. Let us know about the needs you have, and well find a plan for work that is suitable for your property and the roof layout.

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    Roof Sheathing Thickness: Essential Guide

    Theres a new house being built on my street and theyve just finished up the framing and sheathing. One thing I noticed was that the entire house frame was covered in OSB even the roof deck. This got me thinking about how thick my roof sheathing thickness should be on the shed I built.

    The recommended thickness for roof sheathing is thick. Sheathing with a thickness of less than that is much more likely to result in bowing between framing which could potentially compromise your exterior roof material.

    The choice of thicknesses actually varies widely depending on what store you shop at and where you are in North America. When it comes to sheathing your roof, however, it never hurts to go thicker. A thicker panel means less sagging and a stronger roof deck.

    In this article, well go over some tips for choosing the right sheathing thickness for your shed or house, including the types of substrate, techniques for installation, and what works best in different geographic areas.

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    What Kind Of Fasteners Are Used For Roof Sheathing

    Substrates are usually fastened using either nails or screws. Since they are responsible for holding the entire thing together, its always critical to choose the right type of nails depending on the thickness of the boards youre using.

    Ideally, you should use 8d ring shank nails that are specifically designed for roofing. These nails are about 2.5 inches long, making them long enough to fasten just about any roof substrate regardless of its material or how thick it is.

    As for screws, the size will depend more on the thickness of the panels. For example, if youre getting a panel that is 1/2 inch thick or less, a #10 roofing screws would do the trick because its about 3 times longer than the board.

    If youre opting for a thicker roof substrate, you can go for #12 roofing screws, which are about 2 inches long.

    Lastly, you should never try to fix your roof sheathing with staples, as theyre never durable enough to hold up the roof properly.

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    The Gaps Between The Framing Matter Too

    The average roof sheathing thickness is also heavily dependent on the spacing distance between rafters or trusses.

    The further your trusses or rafters are spaced, the thicker the layer of the roof sheathing needs to be.

    For example, the most common spacing between trusses is about 24 inches, while the most common for rafters is about 16 inches.

    Luckily, the APA regulates the maximum distance that a panel can bridge between the gaps, stamped on the roof decking in the form of two numbers divided by a slash.

    For example, if a roof sheathing panel has a stamp that says 24/0. This means that the maximum gap it can hold between framing is about 24 inches.

    Plywood Thickness For The Roof

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    One of the most important factors when selecting the plywood for your roof is how thick each piece should be. Like most other things, there is no one right answer for the plywood thickness of your roof. The answer depends mostly on how far apart the rafters are and the roof loads, which vary based on the pitch of your roof.

    The most common scenario is a home that has rafters set approximately 16 inches apart. In this case, plywood should be a minimum of 3/8 inch thick. However, you may need to consider bolstering the plywood thickness for a roof that has a higher load. A roof that lays practically flat will have a much heavier load than a steeper roof that allows rain, snow, and ice to roll right off.

    Rafters that are slightly farther apart might require ½ inch or 5/8-inch-thick plywood. Many homes have rafters that are even wider at 24 inches apart and will require a thicker sheet of plywood. When this is the case, experts recommend a 5/8-inch-thick sheet. Keep in mind that the load of the roof still plays a role in the plywood thickness. A flatter roof with rafters farther apart may need a thickness of up to ¾ inch.

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    Recommended Thickness Of Shed Roof Sheathing

    The recommended thickness for roof decking on a shed is . At that thickness, you can economically sheath your shed while still getting an extremely solid roof substrate that will stand the test of time.

    OSB board is preferable to plywood for sheathing a shed. Strand board that is tongue and groove makes for a very straightforward install on your shed. If your rafters or shed trusses are widely spaced, or uneven then the tongue and groove give the edges additional strength, particularly if they arent supported by framing at every edge.

    The strand board, besides being cheaper, also works extremely well with tar paper. The rough surface of OSB as compared to the smoother surface of plywood allows the tar paper to hold better and makes installation much faster.

    And while plywood may dry faster than strand board, its important to note that all strand board roof decking you buy these days has blue edges. That means the edges have been waterproofed, which makes it much less likely water will penetrate the board. The adhesives that bond the strand board are also waterproof.

    You could always opt for thicker roof deck panels, but for a shed there is no need to go thicker if your framing is of standard width. Once you start buying panels that are greater than thick, youll notice the cost rise significantly.

    What Are The Different Types Of Roof Sheathing

    As a homeowner, there are two crucial aspects of a home that you must always consider before you sign on the dotted line: the roof and the foundation.

    While your home needs to have a solid foundation, it is crucial that the roof sheathing is installed correctly on the house.

    Like any other building material, roof sheathing mostly comes in the standard size of 4×8 feet and in various materials that range in quality and thickness. The only similarity is that most of them are made from wood.

    For roof sheathing to get the quality mark, modern technology and engineering put together a material that must be graded for exposure in exterior use.

    Here is a list of roof sheathing materials available in the market:

  • Plywood
  • Wafer Board
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