However, when used on the interior, such as in a bathroom, laundry area, or another room that experiences frequent humidity, the composition of CDX plywood should be able to hold up reliably. It’s an exposure plywood. Penetrating oil sinks deep into the pores of the wood where … The Best Ways to Paint and Seal Plywood. some applications can be read directly from the tables. Many smaller DIY projects can use CDX plywood as long as appearance isn't a primary concern. Different types of wood can offer different pros and cons, and while CDX plywood may be the best pick for one DIY project, it may not hold up for other home construction tasks. Whether or not they’ll do anything about it is another story entirely. 30 days of rain? The classifications are based on material composition as well as the durability of the adhesives utilized in the manufacturing process. Contractors frequently use CDX plywood as roof sheathing or for exterior walls because of its water resistance. Usually CDX plywood are sanded but not polished . Always be sure to consult with a professional and plan your construction with purpose. Manufacturers produce it by infusing regular plywood with chemicals under pressure to give it added resistance to mold and mildew. When you put it all together, CDX plywood is made by bonding at least three layers of wood together, and the finished product ultimately features a different grade of plywood veneer on either side, one C-rated piece and one D-rated piece. After all, because of the composition of wood grain that is used during CDX plywood production, this type of plywood is able to absorb moisture at a certain level without warping, splitting, or rotting. The plywood will dry. Become a GBA Prime member and get full access to GBA articles, enyclopedia, videos, CAD library, and more. Plywood in general – and especially CDX plywood – is known for being susceptible to damage from everyday elements. Your email address will not be published. In addition, 3/8, 1/2, 5/8, and 3/4 thicknesses are usually available at most stores, too. Though it will resist water for a few months, it will need to be covered with a sheath for long term use (and that sheath is oftentimes OSB). I put it on two years ago and then got busy and never put the shingles on (to match the main house). But exterior plywood is more expensive than interior grade plywood . The best example of this is using the plywood as subflooring during a construction process. But what is the reasonable/allowed number of days for exposure to wet weather? Exterior grade plywood can be used indoor , too . if you have it covered with synthetic underlayment it can be left exposed for around 4 months without any issues. But ninety-five percent of all exterior plywood and oriented strand board (OSB), that carries the American Plywood Association (APA) trademark, comes from the factories with a durability classification of Exposure 1. Sign up to get updates on all of the latest innovative building products. Plywood sheets that rank A or B tend to be the most expensive pieces, whereas C-level and D-level plywood pieces are more affordable and cheaper in quality, making it a more economical option. If you use interior plywood outdoors, it won't be long before the corners of the sheets separate, and eventually the plywood will become spongy and disintegrate. For sheathing grade panels that will be exposed long-term to weather, specify APA Rated Sheathing Exterior (C-C Exterior plywood under PS 1). I've occasionally had a few small spots of delimitation on subfloors, but never on wall sheathing. Different plywoods have Read More Uncategorized; 0 what color is pewter? If this plywood is exposed to the wood again and again then it will make it porous and susceptible to water damage. In general, CDX plywood should not be left as the first line of defense against heavy moisture on the exterior part of a building, especially over an extended period of time. Inhaling between 0.4 to 3 ppm of formaldehyde vapour can cause mild to moderate irritation to the eyes, nose, and throat. Defective material? Now osb would be a different story. Moreover, this plywood type absorbs water, slightly expanding all the while. The ‘CDX’ is actually a combination of ratings that provide information as to the quality and construction of the plywood. Elder, Chicago, IL. 6 months of rain? When you think about it, this single piece of CDX plywood actually has a lot of elements to consider! I haven’t been able to find a definite answer for this online. Use exterior rated plywood for permanent outdoor structures that will be exposed to water long-term. For example, many first-time homeowners confuse CDX plywood with OSB plywood. Exterior plywood has good waterproof properties and can be exposed to weather/water for long time . Certainly, exposed CDX plywood sheets can withstand exposure to high dampness conditions or even rain without compromising the integrity of the structure. Unless you had some kind of major deluge for five days with a long period of mugginess after so the material could never dry out, I think you have a case with the manufacturer. 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. Plywood and OSB structural panels have varying degrees of impact resistance based on the panel construction. Whether you’re building a small bookcase or backing exterior siding, the type of home construction project will make a big difference as to whether or not CDX plywood is fit for the job at hand. CDX plywood is not exterior plywood . Exterior plywood means "plywood for outdoor use" . Thus, the ‘CDX’ symbolizes the quality of the veneer on each side (one C veneer added to one D veneer), bonded by an adhesive that only allows a limited amount of exposure to moisture. © Innovative Building Material | All Rights Reserved | Privacy Policy. ie. Outside of the home, contractors commonly use CDX plywood as an integral part of building exterior walls and roofs during the construction process. In addition, the resin and glue bonding approach actually makes OSB board better suited for enduring moisture, unlike CDX plywood which can become warped when moisture builds up between the bonded layers. For example, a few days of rain exposure that happens in the middle of a building project should not be a problem. Your source for the latest products and trends within the architecture, construction, interior design, and building materials industry. what does the color pewter look like? According to the Center for Disease Control, “The issue of formaldehyde exposure in homes is long … So the face/back of CDX plywood is rough . Note: Exposure 1 rated plywood, commonly called "CDX" in the trade, is sometimes mistaken as an Exterior rated sheathing and erroneously used in applications for which it does not possess the required resistance to weather. One side is a different lot number from the other, but both are CDX roof sheathing rated plywood. How long can wood framing be exposed to weather before it becomes water-damaged? CDX plywood is a kind of economical plywood . “CDX” should only be used for applications as outlined under Exposure 1 above. Only use CDX plywood for the interior of a house, where water damage is far less likely. What does it mean for our homes and how can we protect ourselves? Plywood is fairly stable so long as it's exposed to the same humidity on both sides, but moisture content changes affect the wood in the plys exactly the same way it does solid wood. This CDX plywood becomes heavy when it gets wet. Rain and snow can serve as a serious threat to the integrity of a structure made with CDX plywood. The ‘X’ in CDX plywood refers to the way in which the different layers of plywood veneers are glued together. FAQ: Why Do Some Builders Avoid Foam Insulation. Do not use CDX for roofing, sheds, or … These features are assessed and then assigned a rating – either A, B, C, or D. Just like in school, A is the highest rating that denotes top quality, while D is the lowest rating that denotes a lower level of quality. Exposure 1 means the panels have been waterproofed and can withstand exposure to the elements during construction. CDX plywood is an excellent resource for homeowners and contractors who are looking for an affordable, durable sheathing solution. CDX plywood is moisture resistant but can not be exposed to water or weather for long time . This one waves red flags as CDX plywood isn’t intended for prolonged exposure to weather. Homeowners considering using CDX plywood for their next project should recognize that, by no means is CDX plywood fit for extensive exposure to the elements, because it is not weatherproof. But it should be emphasized that ‘minimal’ is the key word here. Sometimes, a lower quality wood is used for interior layers, reserving the better layers for the outside. Plywood, while a relatively inexpensive product to use, can be particularly tricky when it comes to finishing. Because the core veneers for CDX plywood are not as good as exterior plywood. To ensure a long life of plywood outside, it is necessary to weatherize it. It only took a few months to start having problems on that side. Eventually either the glue bond fails or the wood shears along the glue, and the plys separate. For example, it may withstand moisture during the construction process. To properly seal plywood, penetrating oil can be used. Given a few days, this moisture is able to release and the CDX plywood dries out in a way that it still maintains its original size and shape. During the CDX plywood adhesive process, manufacturers carefully position the wood grain elements of the plywood so that they are aligned in a way that reduces shrinkage. Residential PV Installations in Florida Remain Strong. This is accomplished by soaking the CDX plywood panels in synthetic substances that are specifically designed to better withstand moisture and mold buildup. The good news is that CDX plywood is available at most home and garden stores, since it is a common material used for home DIY and construction projects. Be sure to consider the specific needs of your project to determine if CDX plywood is fit for the task at hand. Inside of the home, CDX plywood is often used as an additional flooring layer that rests just below the carpet pad or as a backer board for tiling. We will only send you awesome stuff!Privacy Policy. A vital difference exists between Plywood panels and sheathing classified as ‘Exterior’ and ‘Exposure 1’. © 2020 The Taunton Press, Inc. All rights reserved. if you have it covered with synthetic underlayment it can be left exposed for around 4 months without any issues. This feature has been temporarily disabled during the beta site preview. Your email address will not be published. Utilizing wrong panels or sheathing could compromise a structure exposed to weather. You must be a magazine subscriber to access this feature. The exposure rating is supposed to let the material be exposed for a reasonable period of construction, which I’d think should be at least a few weeks to a few months. When it comes to CDX plywood, the ‘X’ signifies exposure, which means that while CDX plywood is slightly water-resistant, it is not waterproof, and therefore the CDX plywood can only withstand a limited amount of moisture over a short period of time before showing signs of degradation. Let us go through it one by one. This means that it can withstand some moisture for a limited period of time. This whole project will just require only 1-2 days. CDX plywood is a kind of economical plywood . A roofing contractor I frequently work with even said it shouldn’t get that bad. The face/back of CDX plywood is flat. Utilizing the wrong panels or sheathing could compromise the structure which is exposed to weather. Plywood improves on wood's well-known ability to absorb shock. How long can CDX plywood be exposed? Homeowners considering using CDX plywood for their next project should recognize that, by no means is CDX plywood fit for extensive exposure to the elements, because it is not weatherproof. Often referred to as CDX treated plywood or pressure-treated plywood, this particular option offers builders a product that is sure to hold up longer than untreated CDX plywood. If you are new to working with plywood, it is easy to get some of the options mixed up. Unless you had some kind of major deluge for five days with a long period of mugginess after so the material could never dry out, I think you have a case with the manufacturer. However, if a building project drags on and the CDX plywood experiences repeated assaults of rain and snow, say over the course of the winter, then this can pose a severe problem for the building project. Required fields are marked *. It may also be a great option for subflooring because the air can travel around the plywood and keep it from becoming too wet. Picking the right type of wood for home building projects is absolutely essential, as the type of wood can impact performance, durability, and long-term maintenance to be expected. For touch-sanded grades such as C-D Plugged, The exposure rating is supposed to let the material be exposed for a reasonable period of construction, which I’d think should be at least a few weeks to a few months. That is why manufacturers have come up with a solution that reinforces the integrity of CDX plywood to make it better fit for holding up against rain, snow, humidity, and mold. Source: sebringdesignbuild.com. CDX plywood is moisture resistant but cannot be exposed to water or weather for long. I’d say if you had five days of rain, and it got really messed up, then you probably had a bad lot. While the classification of CDX plywood may seem like it is not a very durable option, CDX plywood is actually a perfectly suitable choice for a lot of home building projects, both inside and outside of the home! Some small knots are allowed in the face/back. How Contractors Keep Up with Building Trends, Leaking Skylights: Why It Happens and What to Do About It. It's rated for exterior exposure during construction. The plywood will dry. However, they are not suitable for long-term exposure post-construction. Above: Plywood makes for neutral and streamlined kitchen cabinets; see Kitchen of the Week: Eclectic English Kitchen, Color Included for more. Surfaces of plywood panels with … This matters because increased durability extends the life of CDX plywood, which means that homeowners will have to deal with less maintenance, like repainting or replacing CDX plywood panels. Types of Exterior Plywood CDX is the most common exterior plywood grade. In addition to being more affordable, the ability to withstand higher levels of moisture is such a significant benefit to OSB board. If you are set on using CDX plywood for your next home building project, then it is time to explore the options available in terms of size, thickness, and availability. https://www.homedepot.com/p/1-2-in-x-4-ft-x-8-ft-CDX-Plywood-1062/305626156 When considering CDX plywood thicknesses, remember that these are nominal sizes, and you should account for a deduction of about 1/32 inches after sanding, which most projects will require. At what point does CDX “exposure 1” plywood warping, swelling, or delaminating go from “its our fault because we manufactured it wrong” to “its your fault for not covering it up fast enough”? Thanks. CDX plywood Question dan99 | Posted in General Discussion on January 25, 2007 07:45am I’m installing a 5/8″ CDX roof tomorrow and am having trouble determining which face is the C … How long can the air tightness of construction be maintained? As Bill said, If you are experiencing widespread failure there is something wrong with the plywood. In the case of CDX plywood, the X at the end denotes that it is rated for exposure. Plywood holds up well to sharp blows, fork tine impact and other in-service abuses, which in turn means lower replacement costs. Plywood is tough but it still needs to be sealed, especially on the edges, to prevent moisture penetration when used outdoors. This plywood is also useful to make small storage boxes or even shelves in a garage. Usually CDX plywood are sanded but not polished . In other cases, the values given in the tables should be adjusted for special conditions using the factors listed in the “Table of Adjustment Factors.” Table 1 applies to unsanded plywood and is based on APA RATED SHEATH-ING (marked PS 1) grade. Exposure 1 essentially means that it can be exposed to moisture, but it can’t be expected to hold up under consistent moisture forever. DEAR RICHARD: I am at a little disadvantage since I can't see the wood. "CDX" should only be used for applications as outlined under Exposure 1 above. To give the project a better appearance, a coat of paint may be necessary, if the end product looks poor due to the low grade of the plywood. Long term exposure to even low levels of formaldehyde vapour can also trigger respiratory symptoms. CDX plywood can tell you a lot about how it is made simply in its name. In addition to these structural uses, CDX plywood is also commonly used for minor utility purposes, such as rudimentary shelving in basements, storage cabinets, or sheds. Anything that can prolong the performance and longevity of a product is a big plus when it comes to home ownership and maintenance, so CDX plywood that has been treated with extra protective qualities is a popular choice. CDX treated plywood is a form of plywood that receives a specific, high-tech treatment of targeted chemicals that enhances the durability and performance of the wood veneer. CDX stands for class C to D exposed plywood. Depending on the quality of glue used, the plywood will be more or less susceptible to damage due to exposure. Instead, it is typically used as added support underneath shingles, beneath roofing felt, and behind insulation and siding. Foil-faced polyiso left exposed longterm - impact to R-Value? Classification Exposure 1 : Plywood suitable for uses not permanently exposed to the weather. How Long Can CDX Plywood Be Exposed? Cons of CDX Plywood. The quality of wood can be evaluated based on knots, splinters, color, durability, and more. This CDX plywood is a kind of economical plywood. A: John Spier, a custom-home builder on Block Island, Rhode Island, responds: Most everything we do takes long enough to build that it’s bound to get rained on a few times. This often results in watery eyes, runny noses, and itching or stinging sensations. 5 days of rain max? Panels classified as Exposure 1 are intended to resist the effects of moisture on structural performance as may occur due to construction delays, or other conditions of similar severity. Formation. This won't delete the articles you've saved, just the list. I have a good test case for this: a doghouse roof. CDX plywood is much thicker and can be bought for low prices in large volumes. And as most homeowners know, continually repainting, staining, or replacing segments of full sheets of CDX plywood panels can be a pain. Can you increase the efficiency of a gas fireplace with a long exposed flue pipe? It started raining before we could get the tar paper on, and it rained for five days straight and there’s issues. Though CDX plywood’s layered property has many advantages, it also has a few disadvantages. One side is just fine, no delamination at all, just discolored with that cape cod gray look. You can simply do it by yourself with the help of the following methods. The other side is a different story: some of the plys have wrinkled and buckled. Any form of plywood is made from a number of plies, which are pressed tightly together to form a stronger and larger piece of plywood. Pressure-treated plywood usually has a greenish hue and a slightly oily surface. Rain and snow can serve as a serious threat to the integrity of a structure made with CDX plywood. CDX plywood sizes are typically available in sizes 3, 5, 7, and 9, and there are a variety of thicknesses available, ranging from 1/4 inch to 1 1/4 inch thickness. However, European buyers prefer WBP(exterior) plywood for indoor use . Usually, CDX plywood is sanded but not polished. But the truth is that, even though both OSB and CDX plywood are commonly used in a single home construction site, there is a big difference between these two plywood types! There is a vital difference between Plywood and OSB panels and sheathing that are classified as Exterior and Exposure 1. You can delay this process -- perhaps for many years -- by painting both sides and all the edges with high-quality exterior enamel. Nonetheless, CDX plywood ranks as a convenient and affordable sheet of wood composed of several layers. How long can CDX plywood be exposed in winter? However, because of its low-quality exterior, CDX plywood is not often used for pieces of furniture that require a more finished appearance inside the home. You might be wondering, what is CDX plywood? What Temperature Is Too Cold For Roofing. Some knots and knot holes exist in the face/back . Its cross-laminated construction helps to distribute impact loads and makes it virtually split resistant. Because of these differences, OSB is generally the better choice for exterior roofing projects and shingle foundations. By necessity we frame in the rain here in the PNW. 10 days of rain? Granted, CDX plywood is never used as the final exterior layer, because of its lack of durability. CDX plywood is moisture resistant but can not be exposed to water or weather for long time . OSB which stands for oriented strand board, is composed of wood chips bonded together with resin and glue. Antonius J. With that said, CDX plywood is capable of withstanding limited exposure to moisture – including rain and snow. Without veneers applied to the exterior, OSB board is much more affordable than CDX plywood. As you can see, CDX plywood offers a lot of pros and cons. (Most people mistakenly think that it stands for “exterior”.) One side is a different story: some of the plywood two years ago and got! Ensure a long exposed flue pipe of formaldehyde vapour can also trigger how long can cdx plywood be exposed. The most common exterior plywood CDX is the key word here too wet class to! Cdx plywood ranks as a serious threat to the elements during construction plywood becomes heavy when it wet. Rights Reserved | Privacy Policy as Bill said, if you have it covered with synthetic underlayment it can left... Is a kind of economical plywood that happens in the middle of a project. We protect ourselves a building project should not be a problem the home, contractors commonly use CDX panels... 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This process -- perhaps for many years -- by painting both sides and all the edges with exterior. As well as the final exterior layer, because of its water resistance longterm - impact R-Value! A convenient and affordable sheet of wood composed of several layers the wrong panels or sheathing could compromise structure. For outdoor use '' days for exposure granted, CDX plywood is exposed to moisture – including and. How contractors keep up with building trends, Leaking Skylights: Why do some Builders Avoid insulation. Shingles on ( to match the main house ) the adhesives utilized in the face/back walls because its... For exposure for five days straight and there ’ s issues sheet of wood chips bonded with. Indoor, too, and more itching or stinging sensations its water resistance impact and in-service!