The roof is the most important part of any building. It protects from the elements and keeps the interior safe and dry. Regarding building or repairing a roof, choosing the right materials is crucial. Plywood is a popular choice for its strength, durability, and affordability.
There are different types and sizes of plywood available. Therefore, it can be challenging to determine the best option for your roofing project. Understanding the main characteristics of each one can help you find the best one.
In this article, we will explore what plywood is used for roofing – CDX, and OSB plywood. We’ll even discuss the factors you should consider when choosing one for your next project.
What Plywood Is Used for Roofing?
Despite the benefits of plywood, not all of them are created equal. Choosing the right type for your roof is crucial to guarantee its longevity and performance. In this section, we’ll explore the two main two types of plywood. Let’s get into their composition, benefits, and drawbacks.
CDX Plywood
The term “CDX” stands for “C-D Exposure,” which refers to the grade of the plywood. CDX plywood is made up of three layers of wood veneer, with the “C” grade veneer on the front and back and the “D” grade veneer in the middle.
CDX plywood is an affordable option for roofing and is widely available at most home improvement stores. It’s easy to work with and can be cut to size with a circular saw. It’s also strong enough to support the weight of most roofing materials.
The front and back veneers are sanded smooth and can be painted or stained to match the desired finish. The middle veneer is rougher and provides additional strength to the sheet. This type of plywood is also pressure-treated to resist moisture, rot, and decay.
One of the main disadvantages of CDX plywood is that it can warp or bow over time. This can cause the roofing materials to become uneven and cause leaks. To prevent this, it’s important to use high-quality CDX plywood and practice proper care and maintenance.
OSB Plywood
OSB plywood is another type of plywood commonly used for roofing. OSB stands for Oriented Strand Board, and it refers to the way the wood fibers are arranged in the sheet. This type of plywood is made up of several layers of wood strands that are oriented in different directions and glued together to form a strong and durable sheet.
OSB plywood is similar in strength to CDX plywood but is more resistant to moisture and decay. It’s also less prone to warping, making it a more stable option for roofing.
However, it’s slightly more expensive than CDX plywood. The advantage of the extra price is that it’s strong enough to support the weight of most roofing materials. CDX is an excellent choice for high-moisture areas or areas with a lot of snow or rain.
It’s also widely available at most home improvement stores and can be cut to size with a circular saw.
Another disadvantage of an OSB board is that it can be more difficult to work with than CDX plywood. It can be harder to cut and may require more tools or specialized equipment.
CDX or OSB Plywood: Which is Best for You?
When it comes to choosing between CDX and OSB plywood for roofing, there is no one-size-fits-all answer. Each has its own set of advantages and disadvantages. The best option for you will depend on your budget, the climate in your area, and the type of roofing material you plan to use.
Climate: The climate in your area will affect the type of plywood you need for your roofing project. If you live in a location with high humidity, you may want to choose OSB plywood. This type is more resistant to moisture and decay and is less prone to warping.
Roofing Material: The type of roofing material you plan to use will also affect the type of plywood you need. For example, if you plan to use asphalt shingles, you may be able to use either CDX or OSB plywood. However, if you plan to use heavy tiles or slates, you may need to use thicker and stronger plywood.
Cost: Cost is always a factor for construction projects. If you are on a tight budget and plan to use relatively lightweight roofing materials, CDX plywood may be a good choice.
However, if you’re looking for a more durable and moisture-resistant option, OSB plywood may be the way to go. The cost difference may not be significant enough to justify sacrificing durability or stability.
Installation: The installation process will also affect the type of plywood you need. If you are doing the installation yourself, you may want to choose plywood that is easy to work with and requires fewer specialized tools.
Plywood Grade: Grades of plywood are another important factor to consider when selecting the appropriate type of plywood for your roofing project. Plywood is graded based on its quality, with A being the highest quality and D being the lowest.
The grade is determined based on the appearance and number of defects in the plywood, such as knots, splits, and voids.
What Size Plywood Should You Use for the Roof?
It’s important to consider the span and spacing of your roof rafters. The size of the plywood you choose will need to be enough to span the distance between the rafters without sagging or bowing. It also needs to provide enough support for the weight of the roofing material and any snow or ice that may accumulate on the roof.
The most common sizes of plywood used for roofing are 4′ x 8′ sheets, although larger sizes such as 4′ x 10′ or 4′ x 12′ may also be available. The thickness of the plywood will also depend on the spacing of the roof rafters, with thicker plywood being required for wider spans.
For standard residential roofing projects, 1/2-inch or 5/8-inch thick CDX plywood is typically used. This thickness of plywood is usually plenty to span the distance between the rafters in most homes and can support the weight of most types of roofing materials.
If your roof has a wider span, you may need to use thicker plywood. The same can be said if you plan to use heavy roofing materials, such as tiles or slates. If you are unsure about the size or thickness of plywood you need for your roof, it’s always best to consult with a professional contractor.
Final Thoughts
In conclusion, CDX and OSB plywood can answer the question: “What plywood is used for roofing?”
CDX plywood is an affordable option that is easy to work with and can support the weight of most roofing materials. It can be prone to warping or bowing over time, which can lead to leaks or other problems.
OSB plywood is more resistant to moisture and decay than CDX plywood and is less prone to warping or bowing. It can be more difficult to work with and may require more specialized tools or equipment.
When choosing the right plywood for your roofing project, it’s important to consider factors such as climate, roofing material, cost, and installation. It’s also important to choose high-quality plywood that meets the standards set by the APA.
