Roof sheathing is the structural support for your roof’s exterior. OSB is the most common choice for roof sheathing because of its flexibility and low price point. However, despite the popularity, some buildings require stronger support like plywood which can withstand heavier loads. This is because plywood tends to require thicker roof decking compared to OSB.
OSB is the most-used sheathing material for new roofs and roof replacements. You can use 7/16-inch thick OSB sheets without support for areas where the snow load is 30 pounds per square foot because it’s durable and maintains building integrity much longer than other sizes.
You may notice that 3/8″ is another common choice for roof sheathing, however, it is not as durable as 7/16″ and does not typically abide by modern code requirements. Most roofers recommend going no lower than 5/8″ thickness to maintain durability, especially when using OSB.
The APA stamping on roof decking is beneficial to determining appropriate thickness when deciding upon different roof sheathing thicknesses.
Always remember the board you choose must support your roof and the weight you intend to bear on top of it. The roof decking must also be resistant to aging and heavy loads, including harsh weather (as much as possible).
What Size Roof Sheathing should I Use?
A “standard” size roof sheathing thickness does not exist. However, you can look to your trusses (rafters) to help decide on the thickness of your roof sheathing. Reference the APA wood stamp on your roof deck and use it as a guide for determining the right thickness.
There are plenty of assorted sizes to choose from, and calculate what will be structurally sound between your trusses based on the minimum and maximum distances provided. While this is a necessary factor, you should also consider building exterior requirements.
There are many deck sizes. When selecting the size you need, remember the trusses and building code requirements in your jurisdiction. The following sizes are the most common board sizes used for roof sheathing:
½-Inch Roof Paneling
- ½ is recommended for plywood and not OSB since plywood is stronger than OSB
- Thickest roof paneling
- Inflexible
- Good for CDX roofing
7/16-Inch Roof Paneling
- Most used for roof sheathing
- Thick roof paneling
- Less flexible
- Great for OSB and plywood
- Expensive
5/8-Inch Roof Paneling
- Sturdy
- Thick roof paneling
- The most recommended for OSB and CDX roofing
- You should go no lower than this for OSB
- Affordable
3/8-Inch Roof Paneling
- Outdated and should not be used
- Thin roof paneling
- Mostly used with OSB
- Used in older homes or buildings
- Against many modern code requirements
5/8″ or 7/16″ for Roof Sheathing -Which is Better?
5/8-inch paneling is a better choice for roof sheathing than 7/16-inch paneling. This is because of the durability and structural integrity that this additional thickness will bring.
Although 7/16-inch paneling is considered the ‘most common choice for roof sheathing, 5/8-inch roof sheathing is typically one of the best sizes to use when selecting roof sheathing.
However, 7/16″ paneling is a bare minimum requirement and therefore increased thickness is suggested for heavier builds.
7/16″ or 1/2″ OSB For Roof Sheathing – Which is Better?
7/16” is generally considered the absolute minimum where rafters/trusses are spaced 24″ O.C or areas where the snow load is 30 pounds per square foot.
1/2″ isn’t common or even stocked at the lumber yard. It can still be used where rafters/trusses are spaced 20″ O.C but 5/8-inch is recommended for that because it support roof loads for most situations.
7/16-inch OSB is the most common choice for modern roof sheathing, but that does not mean you should use it in every build.
This is only slightly smaller than ½-inch roof sheathing, but some people say there is a noticeable difference in using it for roof sheathing because of its weight-bearing potential.
If you plan to build something that requires extensive weight-bearing, choosing 5/8-inch paneling is a better option because of the additional support.
If you’re still unsure about the thickness of plywood to use on your roof, here is the difference between 1/2 vs. 5/8 roof sheathing.
What is the Minimum Thickness of Roof Sheathing?
The minimum thickness for roof sheathing that many roofers use is 3/4-inches thick. There is no “standard” minimum, however, this is typically the ideal minimum for most roofers.
Many old code requirements allowed 3/8,” but this is very thin, and the more weight placed on this wood paneling, the more likely it is to collapse or sag over time. You can determine the minimum thickness by using this chart or referring to the APA wood guidelines.
Roof Sheathing Code Requirements
Roof sheathing code requirements vary per state, but the guidelines are the same regarding the quality and ventilation of roofs.
Generally, roof sheathing cannot be less than 3/8,” and even then, some jurisdictions require thicker wood. Similarly, different projects will require different thicknesses.
To better understand which thickness your project requires, you can reference the APA wood guidelines provided on the roof paneling. Using this stamp and your trusses, you can calculate the right roof sheathing thickness for your new build!
Types of Roof Sheathing
There are many types of roof decking that you can use for roof sheathing. Depending on your structural requirements and budget, different roof boards may be preferable to others. You should also take into consideration the location and intent of your build.
For instance, if you are building an outdoor gazebo, you might want to invest in more weather-resistant roof sheathing that can withstand the elements.
Here are a few key types of roof decks used for roof sheathing:
OSB
- Lightweight
- Affordable
- Flexible (can take shape)
- Durable
- Poor installation can lead to warping
- Weaker than plywood
- Moisture and weather vulnerable
OSB (oriented strand board) is a lightweight and durable panel made from wood shavings and strong adhesives. This flexible board can easily take the shape of its installation. Because of its low price point and flexibility, OSB is one of the most frequently used paneling for roof sheathing.
OSB can also be easily cut and manipulated. Because of its components, this panel can be bent and shaped effortlessly. Some people may argue that OSB is more durable than plywood despite how much more weight-bearing plywood is compared to OSB.
CDX Plywood
- Thick
- Affordable
- Lightweight
- Moisture vulnerable
- Lower grade (C/D)
This veneer-covered plywood is a smart choice for roof sheathing. CDX plywood gets its name from the two veneer grades used to make it. These veneers are pressed on each side with grades “C” and “D” on the other.
CDX is vulnerable to Moisture, making it a bad choice for outdoor buildings unless it has been pressure-treated for increased durability.
Plywood
- Extra durable
- Weight-bearing
- Weather resistant
- Availability
- Expensive
- Can be difficult to cut
Plywood is an extra durable wood board most known for its weight-bearing tendencies. It is made from thin sheets carved off a spinning log, a process that is finished by a high-pressure veneer cross-lamination for intense strength.
The high-pressure cross-lamination process means that plywood is overly durable and difficult to cut and manipulate. Plywood is a splintering panel and may not cut properly into the shapes you desire which can cause job site difficulties.
Be sure to check the type and size of plywood you use for roofing because it affects the stability of your house.
What is better for roof sheathing, OSB, or CDX?
Every board has its benefit when it comes to roof sheathing. Of course, OSB is a far more popular choice, but the easiest way to decide which wood is best for roof sheathing is to check out the benefits for yourself!
OSB is also less expensive than CDX plywood. So, if money is a consideration in your building, you might want to consider OSB an alternative to CDX plywood. Of course, both OSB and plywood have benefits, but OSB is a better choice because of the weather resistance and durability.
Is OSB better than plywood?
Depending on your budget and structure, plywood can be a better option for roof sheathing than an oriented standard board (OSB).
Both types of paneling are made from wood and held together using strong adhesives. However, plywood is a more heavy-duty option and can support more weight.
Despite being more durable, plywood is still a less-common choice for roof sheathing than OSB. This is because of the low price point of OSB.
While plywood might be more expensive, it requires less maintenance, is heavier-duty, more weather-resistant, and is more weight-bearing. The initial cost might be more but in the long run, roof sheathing that can withstand time and withstand weather is worth the money.
7/16 OSB for Roof Sheathing FAQs
What Size OSB for Roof?
The most commonly used OSB size for roofing is 7/16-inch OSB. It’s slightly smaller than 1/2-inch roof sheathing and considered the absolute minimum where rafters/trusses are spaced 24″ O.C. However, you can use other OSB sizes depending on your location and how far apart you space trusses or rafters.
Conclusion
It is important to find a type of board that will support your structure and maintains its integrity for life when it comes to the roof sheathing. Roof sheathing is not something you want to perform maintenance on, and therefore selecting suitable materials is crucial. From plywood to OSB, there are many options for your roof sheathing.
Many people use 7/16″ plywood for roof sheathing because of its durability and price point, but many people suggest 5/8″ is more durable, and anything below this can cause serious jeopardy.
That is why consulting with a contractor can be helpful before beginning a build. To maintain the structural integrity of your roof, abide by the proper building requirements and always refer to your local jurisdiction’s building requirements.
In addition to building requirements, the type of board you use for your project depends on the price you are willing to pay and the type of structure you are building! For example, 7/16″ is a commonly-used size for roof sheathing, but you should know that it is not always the best!