(Most people mistakenly think that it stands for “exterior”.) Depending on your location, you might find that it is roughly half the price of more traditional CDX plywood. However, OSB does not absorb water easily, but when it does, it takes quite a while to lose the water. Type above and press Enter to search. If you are asking why knowing their differences is so important, here is why. Alternatively, OSB tends to be more waterproof than traditional plywood. Each of these materials has its own unique properties and qualities, and so each is used in specific applications. This makes its dimensional stability better. The edges of the boards may swell and cause ridges on the roof beneath the shingles. If you are not among the people searching for such answers, then you should be because it is important to know what the two are and their differences. But, there is an exception to pressure-treated CDX; they can withstand extreme moisture without getting water damaged. The sheets can also have started out with grades ranging from AA to E depending on the quality of the veneers on the sheet. If you have to choose, you need to know the difference between CDX vs. OSB. Imagine when you want to do your subfloor or roof sheathing and you confuse the two, then two months later, the wood start cracking and rotting, due to water damage. Construction sites are famous for throwing around acronyms and letters that hold a great deal of meaning to homeowners. While some people do prefer to go with traditional plywood, many construction experts make the argument that OSB is better for roofing. The biggest difference is how both react when exposed to large amounts of moisture over an extended period of time. But, as we have seen each one of them has its strengths and weaknesses, making each one of them, best for different tasks. ACX and CDX are both exterior plywoods and aren’t specifying the type of wood. While CDX is strong and will give good results, it is important that you take care of it. However, once it has absorbed water, it dries more slowly. While plywood is generally limited to 8 to 10 feet lengths, OSB panels can be manufactured in lengths up to 16 feet. Alternatively, OSB tends to be more waterproof than traditional plywood. Both plywood and oriented strand board (OSB) are equal in strength and durability. Plywood is composed of approximately 92% - 97% wood, with the remainder made up by primers, sealants, and adhesives such as phenol formaldehyde resin. This costs money and time, but knowing the difference between OSB and CDX does not. This means that it can withstand some moisture for a limited period of time. (339.26 kB) Q: What are the concerns about VOC emissions from exterior plywood and OSB? Think about how often panels get dragged on their edges across a truck bed or across the floor deck in the process of installing them. The protection of the shingles isn’t likely to be enough to prevent the plywood from becoming warped and delaminated over time. OSB also seems to be good for roof sheathing. On page 2 you will see the plywood sheathing info. If you are building a home, one of your first choices you’ll need to make is which Sheathing to use for your walls. This comes as a surprise to many consumers because OSB looks simply as if lots of pieces of wood were glued together. OSB and plywood offer similar (and sufficient) performance in terms of strength and functionality, though plywood is about 7% stronger. OSB is now used for about 70 percent of all floor, wall and roof sheathing in North America. Even though CDX is not waterproof and absorbs water easily, it also loses this water quickly and goes back to its original shape. In the end, many people opt for OSB because it is lower in price and more stable than CDX plywood. However, it needs to be covered and protected long-term. While OSB can pack 50 strand layers into a sheet, plywood only has 5-7, giving OSB a more consistent density, though it does about two pounds or so more per sheet then plywood. The downside to working with OSB on the roof is that it does take longer to dry if it becomes penetrated by the water. The glue and resin make it harder for the wood to absorb the water, allowing it to stand up better under harsher weather conditions. 225 Broadhollow Rd.Suite 310W OSB production in the United States and Canada totaled 25.4 billion square feet (3/8-inch basis), or 59 percent of the total combined production of structural plywood and OSB in 2004. What is the difference between CDX and OSB? But, there is an exception to pressure-treated CDX; they can withstand extreme moisture without getting water damaged. One of the main grading systems when talking about the plywood is the smoothness of its front and back sides. Moisture resistance ... with less glue than plywood. OSB holds up to water quite well, and it is easily seen as water-proof. Save my name, email, and website in this browser for the next time I comment. CDX is best for sub-flooring. Since it will never be visible, it may just be a waste of money. The main difference between the two is how they handle moisture, and oddly enough there are wildly varying conclusions - from very reputable sources - as to just how vapour permeable they are. There are real differences between the various grades of plywood. At the end of the day, you should only really use CDX plywood for interior applications or surfaces that will not see much water. Each layer is held in place by quality binders and adhesives. As mentioned above, the X in CDX stands for exposure. Each layer is placed on top of the other with the graining running in the opposite direction for the opposing layer. OSB or CDX plywood for subflooring? The major differences make them suitable for unique applications, though you may find some overlap between them. Well, when used as exposed decking or subflooring each has its strengths and weaknesses. When choosing a new roof, don’t forget to consider what surface the roof will nailed onto. This is to prevent the wood from absorbing water because when they do. Plywood is made by cutting thin layers of a tree all the way around its circumference. As mentioned above, the X in CDX stands for exposure. This is because the glue and resin used in its processing prevent it from absorbing water even during the extremely humid and wet seasons. Unlike OSB, plywood has been developed into different types over the years in different ways to be used for different purposes. Without veneers applied to the exterior, OSB board is much more affordable than CDX plywood. It is only manufactured to hold up to water for a short period of time. This won’t imply the actual quality of wood itself, e.g. My personal opinion is that OSB performs well on the wall and floor but stick to CDX Plywood on the roof. In such places, it does not get in contact with a lot of moisture, which prevents it from getting damaged. Secondly, OSB panels have a higher shear rating than plywood panels and are thus often installed with greater spans than plywood of the same thickness. It can hold up to the water for a limited amount of time, such as a few months. Similarly, there are major differences between plywood and OSB. The glue and resin that is mixed in with the wood chips makes it much less permeable, so OSB holds up longer in harsher conditions. AC is used when a very nice finish is necessary. They are known as wood structural panels. While this may sound similar to CDX plywood, it is a very different composition process, and OSB board is generally much less durable than CDX plywood. It also warps or swells after water absorption and will not return to its original shape. Both oriented strand board (OSB) and plywood are considered the same by building codes. It is made of wood chips, resin and glue, cast and baked together to produce a CDX-like sheet. On page 6 is OSB Sheathing info and a 24/16 L/180 has a uniform load of 68 at 24″o.c. Oriented strand board (OSB) and plywood are wood structural panels made by compressing and gluing pieces of wood together. The result is a wooden sheet that is proportionally as strong as steel, without the weight that comes along with concrete or steel. ACX, CDX, and BB Formply are the most common types of plywood sold. Plywood and OSB manufacturers try to improve this by sealing the panel edges, but the sealant, whether it is a wax or a paint, tends to get scuffed off. If you are big on saving, then you would want to go with OSB since it is a cheaper version of CDX. Although, OSB typically offers a higher shear rating which adds rigidity to your structure. CDX is veneer plywood, which is manufactured by gluing and pressing together sheets of wood. Both these manufactured sheets of wood are very essential in construction, and truth be told, you can hardly build your house without using at least one of them. The major distinction between these categories is the actual construction of the sheets. One of the main areas that people tend to run into these issues is when they are trying to find plywood for their roofing. In fact, recent price quotes from Denver, Boston and Atlanta put 7/16-inch osb $3.00 to as much as $5.00 per sheet lower than 1/2-inch cdx plywood. Not to mention, you don’t necessarily need to pay the veneer that you will get with the CDX grade of plywood. Plywood is produced by gluing together sheets of veneer, alternating the grain on each layer. Here’s what you need to know. The letters C and D represent the grades of either side of the plywood, while X stands for exposure. OSB is much more waterproof than plywood and CDX plywood. Building codes recognize both plywood and OSB to be alike in their properties and use the phrase \"wood structural panel\" to describe them.However, plywood subfloors are stiffer than OSB by about 10%. This means that the plywood allows being exposed to moisture, but just for a limited period of time A prolonged exposure will lead to water damage. CDX plywood is created by bundling layers of wood together. CDX plywood. At the end of the day, you should only really use CDX plywood for interior applications or surfaces that will not see much water. Plywood absorbs water more quickly, but it also dries more quickly. BY SEAN GROOM Drawings this page: Don Mannes. There you will see that a 24/0 plywood panel has a uniform load at L/180 of 57 at 24″o.c. Even after losing the water, it will take time for it to go back to its original state. To get more informed insight on which one to use for what, you can always ask an expert. COPORATE HEADQUARTERS The National Roofing Contractors Association, the Asphalt Roofing Manufacturers Association. For a decking, or substrate underneath shingles, you can usually use either material. Far too often I see OSB “sag” between the trusses making your roof look wavy. The National Roofing Contractors Association and the Asphalt Roofing Manufacturers Association both gave the thumbs-up of approval to use OSB for roof sheathing, provided that each sheet has approval from the APA – Engineered Wood Association. Because the actual thickness may vary measuring the plywood is the only accurate way to determine its thickness. CDX plywood is produced by gluing together sheets of veneer, with each layer being glued the opposite grain to the one below it. This is a question most people seem to seek answers to. Others, however, prefer to stick with plywood. It isn’t ideal to use for sheds, roofing, or other areas that see consistent rain. It may also make it more likely that the roof will rot over time. OSB, on the other hand, stands for Oriented Strand Board which is a cheaper version of CDX. This provides an inherent system of checks and balances that makes plywood a relatively stable material. When it dries, it is more likely to return to its … However, in as much as CDX is more expensive in relation to OSB, generally, they are both affordable and easily available in lumberyards and stores. Plywood for the Roof: What Should You Choose. If you continue to use this site we will assume that you are happy with it. © 2020 Sherwood Lumber Company. OSB is best for substrate underneath shingles or decking. The ‘best is classified by the least knots, shown grain, etc. Because the adhesive and resin make it more difficult to absorb water, OSB is less likely to expand and contract with exposure to moisture. Determining how well they can hold up to water also determines what types of applications each one is best suited for. In the case of CDX plywood, the X at the end denotes that it is rated for exposure. This includes interior and exterior plywood of any thickness. Up until 2000, plywood held the majority of the market for wall, roof, and floor sheathing when it was surpassed by OSB, which as of 2018, held about 75% of the market share. This is because it is resistant to moisture and therefore, it will not be damaged; at least not for a very long time. He also holds a bachelor's degree in English from Iowa University. The sheets are generally 4 x 8 or 4 x 12 feet in size. These boards are then laminated together using a hot press (basically a giant iron that fuses wood and glue together under heat). I recommend that all roofdecks, especially in moist climates like Seattle, are CDX plywood and not OSB. first, i would just go with cdx but i just started college so money is a bit tight, anyway my room is small (still living with my parents) and im thinking about putting a floor in my attic to give my self some more room. This price spread means that a builder can save $700.00 on a 2,500 square foot house if osb is substituted for plywood sheathing on floors, walls, and roofs. Despite these disadvantages, OSB is still commonly used for roofing. This is because the glue and resin used in its processing prevent it from absorbing water even during the extremely humid a… A 3 / 4 ” sheet is actually 23 / 32 ” thick. However, you will want the finished veneer of CDX for projects like cabinets and furniture. CDX vs OSB sheeting. That is why OSB is sometimes used to secure houses when a hurricane draws near. On the other hand, OSB is produced very differently. Plywood vs. OSB (Oriented Strand Board): Major Differences . Should they go with OSB vs. CDX plywood for the roof? Plywood is made with an odd number of layers for optimal strength and performance. OSB is ideal for these applications where the CDX simply will not work. CDX is used as an upgrade over OSB aesthetically, but no, it’s not winning any beauty contests. What’s a roofdeck? A plywood subfloor generally uses 1/2-inch to 3/4-inch-thick sheets of plywood that have one rough side (which faces down) and one smooth side, which faces up. Within 10 … A: Clayton DeKorne, chief editor of JLC, responds: VOC emissions are pretty much a nonissue for exterior-grade plywood and OSB. Because plywood is rated as shop grade because of defects, almost any type of plywood can end up in the shop grade bin. One of the nice things about plywood is the variety of options you can buy. While construction codes regard all materials similarly as "structural panels," the structure of the plywood and the oriented strand board (OSB) is somewhat different. The roof deck is the surface underneath your roof and roofing underlayment. Is Rain on a Steel Roof Louder than on an Asphalt Roof? Cover it on both occasions and maintain it regularly to ensure it does not get damaged. OSB absorbs water more slowly than plywood, which can be beneficial in areas of low dampness. Are there any roofing situations where osb should NOT be used? OSB vs Plywood: Fast Fact. The first piece of wood is placed so that it rolls “up” while each subsequent layer is laid 90 degrees to the one below it, and upside-down. This means that the plywood allows being exposed to moisture, but just for a limited period of time A prolonged exposure will lead to water damage. Oriented strand board (OSB) combines wood chips, glue, and resin into the shape of a sheet of plywood and bakes them together. You will need to remove everything and start all over or ask a specialist to correct the mistake. comparing the quality of luan and pecan tree, but rather the finish of surfaces. For example: Marine plywood is more moisture resistant than standard plywood, is better used in constructions where exposure to water is likely (e.g. Many of these abbreviations that you hear will represent different types of plywood that are used for subflooring, roofing, and everything in between. This can result in visible deflection of the panels between the supports and can telegraph through causing a wavy appearance to the roof. Specializing in building and renovating homes, Thomas Luttrell has worked in homebuilding since 2002. Plywood is often sold in 1 / 4 “, 1 / 2 “, or 3 / 4 ” nominal thicknesses, but the actual thickness is often 1 / 32 ” thinner. Even as affordable as they are, well-reputable stores like Sherwood Lumber still offer insane deals and discounts. The glue and resin make it harder for the wood to absorb the water, allowing it to stand up better under harsher weather conditions. As a result, OSB floors are more li… However, there is one area of concern in which plywood beats OSB. CDX PLYWOOD vs. OSD PLYWOOD OSD and CDX plywood are both commonly found on construction sites, because builders and contractors rely on both types of plywood to get the job done. Learn how to tell these two apart and how to use each one. Structure or Basic Composition. Trubord 7/16 is rated 24/16 and 15/32 and 1/2 are rated 32/16. Don’t get frazzled and confused during the construction or repair of your home. Which is the better option, plywood vs. Advantech? Plywood vs. OSB Protect an unfinished home from the elements—and a finished home from the consequences of plumbing disasters—by starting with a … Other engineered wood panel types, such as particle board or OSB, contain a much higher percentage of glue, and since glue is heavier than wood, these panels tend to be significantly heavier than plywood. OSB holds up to water quite well, and it is easily seen as water-proof. It isn’t ideal to use for sheds, roofing, or other areas that see consistent rain. CDX and OSB are used for almost similar things, but because they have different features, one is better applied in some tasks and the other one on other tasks. Before you can really grasp the different ways to use CDX plywood vs. OSB, it can help to have a better understanding of what each of them is. OSB and plywood vary in terms of durability. By Clayton DeKorne Download the PDF version of this article. than CDX plywood. Now that we both agree that knowing the difference between the two is important, let’s start by knowing what they really are. It is also used for roof sheathing. What is the Actual Thickness of a Sheet of Plywood. While you may want to consider a different type of roof sheathing, CDX plywood is still not a great choice for your roof. VOCs in Plywood vs OSB. Some design and construction professionals have come to swear by oriented strand board. But take care, it also requires that you use water-resistant coating at the edges. It is often less expensive than CDX plywood because this manufacturing process doesn’t require the same costly veneers found on the front and back of CDX plywood. Sherwood Lumber uses cookies to ensure that we give you the best experience on our website. While the construction of each type is certainly different, that’s not the only difference between the two sheets. Should you use CDX (plywood) or OSB (oriented strand board) for roofing plywood? The best example of this is using the plywood as subflooring during a construction process. Melville, NY 11747, Terms & Conditions The only exception to this can be the pressure treated CDX, because it can survive outside for decades without a protective finish. While OSB and plywood appear similar and are generally interchangeable, the different ways that each material is manufactured contribute to … Next time you find yourself in the middle of a construction project, make sure that you understand the real differences between CDX vs. OSB plywood. Plywood Holds the Moisture Advantage Over OSB. Press Esc to cancel. The result is that the tendency for the boards to warp into their original shape is diminis… In 2001, oriented strand board surpassed plywood in terms of square footage produced. Making the right choice is easy when you understand the inherent differences between these starkly distinctive types of materials! 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