What Type Of Plywood For Roof
Plywood is one of the most common construction materials often used in flooring, but did you know you can also use it to build a roof?
In todays article, were sharing a complete guide on plywood for roofing, from its types and advantages to its available sizes and recommended thicknesses. Lets get started!
Roofing Plywood Cost Per Sheet
The average cost of roofing plywood per sheet is between $70 and $100. The standard size of each sheet is 4ft x 8ft.
The price of plywood depends on the thickness of the sheet, which makes sense. When you pay for thicker plywood, you are paying for more material that promises to be more durable than thin plywood, so you will probably pay more per sheet.
How Much Does Marine Plywood Weigh
: Despite its name, this is not a waterproof plywood. It is manufactured using water-resistant adhesive and very high quality outer plies which help prevent moisture from penetrating the panel.
It is designed to be used where the material will be subjected to higher-than-normal amounts of moisture, such as in coastal environments.
A typical 4 x 8 sheet of 1/2-inch Marine Plywood weighs around 51 lbs.
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Is Roof Sheathing Necessary
Roof sheathing makes your roof strong, and that makes it necessary for almost any home construction. A building can only be complete when it has a roof over it, but a roof is not quality if it is not strong.
The roofs structure is comprised of rafters and trusses of different sizes, e.g., 3×2, 4×2, and 6×2 wooden frames that are spaced on intervals of between 16 and 24 apart in both length and breadth.
Most roofing materials come in the form of asphalt shingles or tiles, and because they are smaller in size and are laid nearby, the tiles wont have the base to apply on if the roof does not have a sheathing.
But as much as homeowners only think of a roof sheath as the surface for holding shingles and laying out tiles on the roof, a roof sheathing has several benefits as an added advantage:
Whats Better For Roofing: Osb Or Plywood
OSB is the better option for roof decking because it is cheaper and comes in a wider variety of larger sizes than plywood. Strand board does not react as well to moisture as plywood does, but it will have a more consistent thickness and fewer weak spots like knots than plywood.
If you are concerned about moisture getting into your sheathing, then plywood may be a better option. Plywood dries much faster than OSB because it is not as dense. There are usually only several layers of plywood per sheet while there are up to 50 layers of wood chips in a sheet of strand board, plus much more adhesive than a sheet of ply.
Since there are so many layers in OSB it is somewhat heavier than plywood. It takes water longer to penetrate it, but once it gets into the sheet then it takes a much longer time to dry. A board that stays wet longer is prone to sagging, which is why strand board tends to sag over time on many homes.
Finally, if you are going to sheath a shed that isnt heated, then OSB would definitely be a better option, provided you install the roofing material properly. There wont be any condensation issues, so your roof deck is liable to stay dry. In that case, strand board is best instead of plywood.
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What Kind Of Plywood For The Roof
When it comes to choosing what kind of plywood you need for the roof, it is important to understand the basic categories that you can choose from. Most construction sites will consider the use of either OSB or plywood for the roof.
CDX plywood is a construction-grade type of plywood that is designed for exposure to the elements. It can withstand moisture for a brief period of time but may become warped and delaminated with consistent exposure to the elements. This particular type of plywood is crafted from layers of wood stacked on top of one another with alternating grain patterns in each layer. The alternating grain gives the plywood a system of checks and balances that allow it to expand and contract evenly across the sheet.
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Alternatively, OSB is created from wood chips, resin, and adhesive that is baked and formed into the shape of a sheet of plywood. It is extremely resistant to moisture. However, when it is penetrated by water, it takes a very long time to finally dry out compared to CDX plywood. The edges may also swell during this time, creating small yet visible ridges on the roof where the boards meet.
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Will Cold Climates Require A Thicker Roof Sheathing
Whether youre sheathing a house or a shed, you should always keep the weather in mind while deciding on the suitable thickness for the roof sheathing, especially in the winter.
This is because winter is where the majority of the rain and wind occur, which are the true test of the structural integrity and durability of the roof sheathing.
Moreover, in northern states, winter is often accompanied by snow, which puts a tremendous load on the roof in terms of sturdiness and moisture resistance.
Another specification that the APA includes on the label of the roof sheathing is the maximum load it can support, which is usually measured by pounds per square foot or psf.
If you live in an area where snow falls regularly, its always better to err on the side of caution and go for a roof with a load tolerance of about 50 psf or higher.
Of course, panels rated at 50 psf or higher are usually thicker than average roof sheathing options, and they usually cost a bit more, so you have to keep that in mind.
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Plywood’s Advantage Over Osb
That, in a nutshell, is the one big advantage plywood holds over OSB. The greater ability a wall has to dry, the more durable it will be, and everyone agrees that more moisture will pass through plywood. This is not a suggestion to never use OSB, but it is a recommendation to factor all the variables and make sure that collectively the components of your wall assembly will not trap moisture inside.
What Thickness Should Roof Sheathing Be
The typical thickness of roof sheathing is about 7/16-inch, which is just under 1/2-inch.
What is the best sheathing for a roof?
The two most popular roof sheathing materials are OSB and plywood. Both of these are more economical than radiant barrier roof sheathing and zip system roof sheathing. Because of their affordability, most homeowners opt for one or the other. However, there is some debate as to which material is the best.
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What Kind Of Plywood Is Used For Concrete Shutters
Shuttering plywood is suitable for concrete shuttering, site hoarding, roofing or flooring. Constructed with high quality phenolic adhesive WBP Water and Boil Proof standards . Shuttering plywood has a quality pine face with a softwood core.
How much plywood should I use for roof rafters?
The answer depends mostly on how far apart the rafters are and the roof loads, which vary based on the pitch of your roof. The most common scenario is a home that has rafters set approximately 16 inches apart. In this case, plywood should be a minimum of 3/8 inch thick.
What Is Roof Decking/sheating
Also known as sheating, decking is basically where the roofer attaches the shingles or whatever your chosen roofing material is. Obviously, it should be graded for exterior use meaning it should be able to withstand rain especially during the construction of the roof. The waterproofed coat of plywood makes it a top choice along with OSB, planks and wood boards.
What is plywood? Plywood is made out of laminated sheets of veneer. Its a top choice because of its characteristic wherein it expands evenly when exposed to water unlike OSB wherein only the edges expand.
Speaking of OSB, its a top choice of homeowners looking for something more affordable than plywood. As a warning, its considered by some to be inferior in quality as compared to plywood. Well discuss plywood vs OSB more later.
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What Kind Of Fasteners Are Used For Roof Sheathing
Substrates are usually fastened using either nails or screws. Since they are responsible for holding the entire thing together, its always critical to choose the right type of nails depending on the thickness of the boards youre using.
Ideally, you should use 8d ring shank nails that are specifically designed for roofing. These nails are about 2.5 inches long, making them long enough to fasten just about any roof substrate regardless of its material or how thick it is.
As for screws, the size will depend more on the thickness of the panels. For example, if youre getting a panel that is 1/2 inch thick or less, a #10 roofing screws would do the trick because its about 3 times longer than the board.
If youre opting for a thicker roof substrate, you can go for #12 roofing screws, which are about 2 inches long.
Lastly, you should never try to fix your roof sheathing with staples, as theyre never durable enough to hold up the roof properly.
Choosing Plywood For The Roof
Choosing the right type of plywood for the roof is one of the most important construction decisions that you will have to make. It determines how long your roof will last and how well it will protect the contents of your home. Both OSB and plywood for the roof have been approved for use, so it may come down to what you feel most comfortable using. Be sure to weigh the advantages and disadvantages of each option before you decide which way to go for your new home or your updated roof.
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Roof Sheathing Gable Roof
The Results
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So What Type Of Plywood Is Best For Outdoor Use
ACX exterior graded plywood is the best option for outdoor building. It is relatively affordable, and doesnt sacrifice quality for price.
However, if you are working with a tight budget, then consider buying CDX plywood. Still, it is worth noting that this particular type of construction-graded plywood, both looks and feels rather shabby. So, it is more commonly used as sub-flooring material.
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How To Calculate How Much Roof Decking You Need
Aside from determining how thick your roof sheathing should be, you also want to calculate how much material you need upfront. The average-sized plywood sheet of four-by-eight feet is 32 square feet. When you know your roofs total square footage, simply divide it by 32, and youll get the needed amount.
Also, make sure to calculate a 10 to 15 percent waste to ensure you dont run out of material mid-installation. This will give you a pretty precise figure on how many square feet, and therefore the number of sheets, you need to buy.
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Type Of Plywood Used On Roofing
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Builders love plywood for its water resistance, structural stability and low cost. They also love oriented strand board, though. It costs even less and is comparable to plywood on the other two counts, and they increasingly prefer OSB for roof sheathing. Either is an acceptable choice in most jurisdictions.
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Can I Use 1/2 Inch Plywood For Shed Roof
If the shed is for light tools then 1/2 inch pressure treated plywood is acceptable. If the shed is for heavier storage, then pressure treated 3/4 inch exterior-grade CDX plywood is the best.
Is 710 plywood a specification?
Is shuttering ply strong?
Shuttering Plywood is manufactured from softwood, making it extremely light weight and strong.
Is Plywood Ok For Using Outside
Yes, but only if it is a plywood type that has been specifically created to be water-resistant.
This is achieved when plywood is glued together using a waterproof adhesive. This makes the plywood stronger even when its repeatedly drenched by rain.
Can Regular Plywood Get Rained On? No. Regular graded plywood will warp if it is exposed to water for a prolonged period of time.
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Where To Put Vapour Barriers :
Materials that act as vapour barriers , including certain types of insulation, must be located within the assembly so that moisture moving from the inside to the outside does not condense and accumulate within the assembly. This means that vapour barriers should be located on the warm side of insulating materials. Canada Mortgage and Housing Corporation
Manufacturers spec sheets weve read claim perm ratings of between 1 and 2 perms, but that doesnt inspire a great amount of confidence given that that conclusion was obviously arrived at by using the most favourable of the available numbers. At least some of these panels are said to be perforated to allow for increased moisture permeability, but a close look at the panel in the photo above at least, shows no visible perforations. So if they are there, they are no bigger than a needle point.
It would seem then possible at least, for moisture to migrate through the EPS and condense on the sheathing, certainly if you believe the lower of the OSB perm ratings. Without seeing the long term results of insulated sheathing products or at least some independent research on it, Its hard to know what will happen.
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How Many Plywood Sheets Will Your Roof Require
You will have to work out the amount of plywood sheets youll require, bearing in mind that a sheet of plywood is 4×8 feet in size, with a surface area of 32 square feet.
So, with the average roof size being 1,700 square feet, this means that youll need approximately 53 sheets of plywood.
To calculate how many sheets of plywood your roof requires more accurately, you should follow these steps.
If you cant directly measure your roof, you can use a calculation that converts the floor area covered by the roof so you can get an estimate of how much plywood you will need. So, if your house has a main area of 20 by 40 feet and a wing thats 15 by 20 feet, multiply 20 by 40 to get 800 square feet.
Then multiply 15 by 20 to get 300 square feet for the extra wing. Add 800 and 300 to give you the total floor area, which will be 1,100 square feet. Then add about 20 percent to the number to cater for the roof slope, which gives you 1,320 square feet of roof area. Finally, divide 1,320 by 32 so you get 41 plywood sheets.
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What Makes Plywood A Good Option For Roofing
The fundamental framework of roofs consists of rafters and trusses. On top of this frame, a flat deck should be laid down to fix a final material onto it, such as felt or tiles.
One of the best materials you can use for making the deck of a roof is plywood, and heres why:
- Plywood is durable and inexpensive since the deck of the roof wont be visible once the finishing material is installed, itd be a waste and a huge, unnecessary cost to use solid wood as looks dont play a factor in the matter.
Instead, using plywood provides the required strength for supporting the load of the final material on top of it and heavy ice or snowfall while being very affordable.
- Plywood resists moisture well thanks to its impressive performance upon exposure to water for extended periods, plywood makes for a handy material in outdoor uses such as roofing.
Even if it does expand or swell due to moisture, this happens uniformly across the entire deck so that it doesnt affect the overall structure of the roof. Additionally, plywood quickly dries out, which minimizes the risk of mold building up and other moisture issues.
- Plywood is easy to work with cutting plywood to size is a simple job whether youre using circular saws or handheld saws. The standard sheet size for plywood is 4 x 8 feet, which strikes a good balance between being a reasonable size to work with and providing coverage of a fair surface area of the roof.
Maximum Roof Sheathing Thickness
It is essential to pay close attention to the markings on the panel boards because various materials with the same thickness are rated for different spans.
The roof sheathing thickness is essential for weather resistance, as well as strengthening the overall roofing system. Thicker boards will provide a more sturdy rooftop and will prevent sagging between the trusses. Less bending implies a much more firm layer for roofing material, which extends the roofs durability.
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