Exterior plywood is a type of wood that is designed to be water-resistant and strong enough for outdoor use, especially in areas exposed to water and humidity. It is often made from Douglas fir and is divided into A-grade, B-grade, and C grades. The most popular grade is CDX, which is moisture-resistant but requires lower-grade adhesives.
For outdoor use, the best plywood is BWP-grade plywood reinforced with pressure treatment. Marine-grade plywood can hold up for up to 5 years in most outdoor use cases. Exterior panels should have a “CC” grade or better. Examples of exterior panels include BC Tongue and Groove (T and G) Underlayment, AB Marine Grade plywood, and AB Tongue and Groove (T and G) Underlayment.
The best plywood grade depends on the desired look and is typically considered the worst for aesthetic uses. For outdoor projects, marine plywood is recommended due to its resistance to moisture and harsh weather conditions. Marine plywood is available in grades A-A, A-B, and B-B and is usually made from wood without knots. Pressure treated plywood is recommended as it is rough and takes a lot of work to spackle and sand but will last longer.
This guide explains the different uses of plywood, sizes, materials, and its rating and grade system so that you can choose the best plywood for your project. Marine plywood is a high-quality timber product composed of multiple layers of wood veneers bonded with water-resistant weather and boil proof (WBP) glue.
📹 Marine Grade Plywood
What is exterior plywood called?
Exterior sheathing plywood, rated CDX, is used in construction for exterior walls and roofing due to its resistance to moisture. It is essential for protecting internal structures from the elements. Subfloor plywood, thicker and more water-resistant than standard plywood, is often used in construction due to its tight, squeak-free floor surface. Both types are crucial for constructing the outer layers of buildings.
Is CDX plywood good for outdoor use?
CDX plywood is a moisture-resistant material with an exterior-grade adhesive, making it suitable for environments with intermittent moisture exposure. It is cost-effective compared to higher-grade plywood, making it an ideal choice for large-scale construction projects. CDX plywood is versatile, suitable for various applications such as structural sheathing, subflooring, and roofing, making it a popular choice in the construction industry. Its balance of quality and price makes it a popular choice for builders and contractors.
What is the best grade of exterior plywood?
Marine-grade plywood, manufactured with AA, AB, or BB veneers, represents the pinnacle of plywood quality for applications requiring smooth surfaces, rigidity, and long-term stability. This grade of plywood is distinguished by the absence of core voids and the lack of span ratings, which are inherent characteristics that set it apart from other plywood types.
What is the most waterproof plywood?
Marine-grade plywood is a high-quality timber product made from multiple layers of wood veneers bonded with water-resistant weather and boil proof (WBP) glue. It is commonly used in boat building, particularly for boat hulls, due to its excellent pliability and water-resistant properties. To make an informed decision on which waterproof plywood to use, experienced builders should be familiar with both exterior and marine plywood.
Marine plywood is a popular choice due to its excellent pliability and water-resistant properties. Understanding the differences between these two types of plywood is crucial for making informed construction decisions.
Which is stronger, OSB or CDX?
OSB is suitable for medium humidity environments and is less strong than CDX but can withstand moisture exposure for a short time. It is commonly used for walls, floors, and roof sheathing. OSB is not fully waterproof and cannot withstand constant water or moisture exposure. Its gapless structure and resin content allow it to withstand moisture longer. CDX, on the other hand, has low moisture resistance but is treated for better durability and improved termite and rot resistance.
What is the difference between marine plywood and exterior plywood?
Marine plywood and exterior hardwood are both suitable for outdoor use, but the main difference lies in the material used. Marine plywood is made with more permanent, weather-resistant glues and defect-free, high-density hardwood, ensuring a smooth, water-resistant surface. This makes it the most robust and water-resistant option available. Marine plywood can last between 15-25 years, depending on application, quality, and exposure.
To ensure maximum longevity, it is essential to follow all recommended installation and sealing instructions when using marine plywood in projects. Other types of plywood have looser restrictions on wood type.
How thick should plywood be for house exterior?
Standard plywood sheets are typically ½ inch thick, with non-standard thicknesses ranging from 1/8 inch to ¾ inch. Softwood sheets are often combined with ¾ thickness. Standard plywood sizes are slightly thinner in reality. It is used in various industries such as industrial wood, pallets, crates, integrated packaging, foam packaging, services, energy, oil and gas, automotive, aerospace and defense, chemical, plastics, film, pharmaceuticals, food and beverage, consumer goods, HVAC and appliances, heavy industrial, pipe, steel, heavy equipment, agriculture, lawn and garden, logistics and transportation, and export compliant lumber and packaging. Companies like Conner Colorado and Guardian Packaging are involved in the distribution of standard plywood.
What are the disadvantages of marine plywood?
Marine plywood is a higher-cost option compared to standard plywood due to its waterproof adhesive and high-quality materials. Its weight is also a concern due to its multiple thin layers and denser construction. This makes handling and transporting difficult, especially for large projects. Marine plywood may only be necessary for certain projects, and standard plywood may be more cost-effective for those without water or moisture exposure. When comparing marine plywood to other types of plywood, it’s crucial to consider the specific needs of your project, as marine plywood excels in moist and wet environments.
How thick is plywood for house exterior?
House frames are made stronger by using plywood to sheath them, providing a surface for siding installation and making the structure stronger. For structures with siding only connected to the plywood sheathing, thicker plywood is required. Standard thickness is ½” thick plywood for walls, but the International Residential Code requires 3/8″ wall sheathing when studs are spaced 16″ apart and siding is attached to the studs.
Local building codes often require 3/8″ plywood for roofing, but using ½” or 5/8″ plywood results in a longer-lasting and safer roof. Thin plywood is often insufficient for roofs, especially in large areas with large spaces between trusses and rafters. Thin plywood also makes it easier for shingles to fly off in high wind situations.
When choosing plywood thicknesses, consider the finished product requirements, such as furniture and construction, and the weather conditions of the building site, especially high winds. It may take only one severe storm to prove the worth of investing in thicker plywood.
What plywood is on house exterior?
Exterior plywood sheathing is used on weather-protected building exteriors, typically rated CDX with a C-grade face, D-grade back, and X for weather exposure. It has exterior-rated glue for durability. Plywood underlayment is water-repellent and thicker than normal plywood, suitable for use under hardwood, carpet, tile, and vinyl floor coverings. For a squeak-free floor, look for tongue and groove panels labeled “T and G”.
Which plywood is best for outdoors?
Exterior plywood, often made from Douglas fir, is weather and water resistant, making it suitable for outdoor use in areas exposed to water and humidity. It can be used on decks, walkways, sheds, outdoor shelving, and outdoor structures like gazebos, benches, or planters. There are various types of exterior plywood, with the most common being CDX or ACX. The construction grade is indicated by an X, with A being a premium grade for high-end uses and CDX being a more affordable option.
The plywood layers can be made from veneers, high-density hardwood, or light hardwood. While it may not be visually appealing due to visible knots or blemishes, some types have cleaner appearances, making them ideal for projects requiring aesthetic appeal. The construction grade is indicated by the first two letters, indicating the plywood’s construction grade.
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There is one REALLY good use for heavy MDF is for speaker enclosures because you want the speaker to do the vibrating not the box its in. Of course you need to put something over the mdf after you use it as a core but you want that heavy denseness to give the speaker something to push against. IF you want it to NEVER come apart use GE clear Siliconne 2.
Thanks a lot, very valuable content! I live in Baltics and have very similar piece what you showed in the article, but kind of from the vendor directly :). Could you please make a article on how to work with it i.e. what sanding grid do you use, what type of oil (osmo?) or finishing as such would work the best? Also interested in Oak veneered plywood. Thank you in advance!
By any chance have you made articles about tools, I need small tools to fit my hands and light enough to work with in small projects such as small boxes, curved and making ornate projects out of wood, those kinds of tools with precision. I appreciate any information you may give some of newbies. : ) thanks
FYI. The stuff at home Depot here is actually labeled as “Sande” ply, not “sanded”. I googled it and supposedly it is a hardwood called Brosimim utile…or otherwise known as mulberry wood. Otherwise yeah, not the best quality, and the aesthetics can vary pretty drastically from what I’ve seen, so you’re assessment is still spot on.
First I have to say – I wish I had a shop that looked like what we see behind you! I think the two contractors that worked on my roof should have watched your article before working on my house. I caught the first contractor using interior birch on my roof sheathing! Fired! Second one – the crappiest job ever and I don’t think CDX they used for the soffit (?) easement (?) was thick enough. The whole roof sheathing was supposed to be replaced but that’s a big story right now.
I’ve been that guy… I parked super far away from everyone going into the store because I knew I’d make sawdust… of course when I came out of the store, wouldn’t you know it someone parked by me 🤣. I still made all the cuts I needed with my circular saw and guide. I used HDs flat cart. Being careful not to let the saw hit the kart (I didn’t have foam)
The problem with buying plywood or any lumber today is, there is not one straight piece of plywood or lumber in any store or lumber yard today, this include cabinet grade too. Plywood as well as any sheet of wood is bowed. Lumber is torqued and or bowed, twisted, large knots, chunks taken out of lumber, split and cracked, etc.
It’s actually Sande, not sanded, Plywood. It’s a marine grade soft plywood. I used to use it pre-pandemic for shop furniture because it was significantly flatter than pine, but now the hardwood veneer plywoods are basically the same price. If I had plywood going outside like a dog house, I might use the Sande Plywood.
I don’t know about other areas but there’s a guy up in Rapid City who sells horrible Chinese sanded hardwood plywood that is so wet it curls in the bunk and delaminates without any stress other than air drying. There’s another outfit in Fort collins that always has fine US made plywood at about 50% higher prices and 50% thicker face veneers. If you’re lucky you’ll get what you pay for.
A decent plywood dealer is going to be a better value, and often even a better price than a big box store. I have found the sales people very helpful at a few shops, though some don’t want to deal with hobbyists. They also help you load without asking. I will gladly pay them more, but usually the price is really close or less. Bottom line – avoid the big box.
Good info, Thank you. Buying in a hurry costs also. Because I grabbed what was close, my chicken coup ended up with a Birch plywood floor. The worst part was we were installing peel and stick tiles in the henhouse also. I realized the mistake, but since the 2×4’s were $10 each that day, I wrote it off as a bad day to buy, but we finished the project on time. Here we are 2 months later and I just paid $3.50 for the 2×4’s at the same store. I bought an extra 10 boards for good measure. Take care.
I understand why you don’t like MDF however I found that painting and priming etc. can waterproof it further and add a little more structural strength. Also if you decided to do other fastening styles it works really well with as well I think explaining that could help as well. I was also curious what you thought of HDF. I have been doing a lot of research on it and I am enjoying the projects I have seen others do with HDF as well as potential projects I’d like to do? What do you think? Baltic Plywood is definitely the way to go though I agree with you especially over load bearing cabinetries or furniture for the most part 🙂 depends on design though in my opinion 🙂
I avoid using any of the big box stores. They are infuriating. I have a family owned lumber yard that’s been there for 100 years. I hit the lumber bays and I have an attendant ready to help me in anyway possible, culling lumber to helping me move material, none of this self service. I may pay a little more but I get real customer service. I hit the contractors desk even though I’m not one, I run thru my shopping list and head for materials barn where I’m greeted by a real human and loaded out in minutes.
MEN-ards, not “mainerds” :). Our local Menard’s stores it’s plywood with a shelf underneath; sheets are flat and surfaces look very good. Selection is good, and yes they have 4×8 birch plywood (~$69 for S1S). Home Depot lays the sheets across brackets, causing it to look wavy. Price at HD is the same for lower quality sheets though (supply issue? Maybe). I’m a fan of both. We have a Lowe’s as well here.
The string that you found in your plywood @10:35 is from a veneer composer. It recycles pieces of veneer that would normally be thrown away for being too uneven, fish tailed etc, cuts them so they have straight edges and then glues them together with long strings before cutting them into new 4×4 or 4×8 sheets of veneer which can then be used for the core pieces. It saves a lot of wood from just going into the chipper. Also, the red glue found in the Chinese plywood is typically urea formaldehyde, which is not water proof and doesn’t lock in the formaldehyde as well as the black phenol formaldehyde glue used in the outdoor panels, so be careful when you sand or cut it.
This was incredibly helpful. Even the tip about how to look through plywood. As soon as you said to search through the stack, I instantly thought, ‘oh, great, now I have to ask for help everytime’, but then you showed how to sort and I can totally do that on my own 😄 So if y’all see a lady in the parking lot, cutting up plywood to fit into her car, it’s me, I’m that lady 😄
Hello. I love your article. I’m a novice to wood building/DIY’er stuff. I want to make my own desk chair mat versus buying a hard plastic one. I plan to “cover” the top of the plywood with vinyl adhesive squares. Your opinion please: What would you recommend as far as the thickness of plywood to use (I was thinking of a 1/4 inch)? I am not sure if this is not think enough (I’m a 180 lb guy on your typical office chair). Also, if you have a type of plywood (birch, pine, etc…) I should get, please include that as well. Any help/advise would be most appreciated.
“Stack It Back” Wow, what a concept! Sure would be nice to go to these big box stores and find a rack that’s not all jumbled up with just about anything the store sells. I also overheard one of the guys that work there b1tching about the lazy customers…. probably the same ones that leave the shopping carts in the parking spots.