OSB Boards used for the deck should be: a minimum thickness of 18mm (these will be able to span up to 600mm). 5/8-in x 4-ft x 8-ft Tongue and Groove OSB Sheathing. Plywood's Advantage over OSB? With this thickness any deflection under dead loads only (the weight of materials only) should prove to be imperceptible. However, if you are retrofitting an old house or shed, you may encounter unusual spacings which will indicate your roof decking may need to be thicker than the spacing and label indicate. Many builders who are redoing a roof that has original dimensional lumber as a roof deck will put plywood or OSB over the top before finishing the roof with new roofing material as it is simply a more reliable substrate than many pieces of lumber on end. Impervious to any waters ingress. A building can be a tough decision. You put underlayment on top of the roof deck to act as a moisture barrier, and your primary vapor barrier will bein your attic, not beneath your shingles or other outer layer. The thickness of your roof sheathing is important. Plywood is more expensive but slightly stronger. What is the Minimum Thickness of Roof Sheathing? While that might not sound like much weight, just know that you’ll multiply that number over the number of square feet on your roof. It is now more popular than plywood, commanding 66% of the structural panel market. Therefore if you have a total of 2000 square feet, then the total load spread out over your roof is multiplied times 50, which is 100,000 pounds. was wondering if i should use the same OSB or some other thickness? which thickness OSB for a shed roof i posted 7/16 OSB on the walls of my 11x9 shed, now i am ready to make the roof. As a result, OSB floors are more li… £5.90 per SQM. OSB Thickness for Wall Sheathing. for pricing and availability. Once you start buying panels that are greater than ⅝” thick, you’ll notice the cost rise significantly. What Size of Roofing Nails for Roof Sheathing? If deflection (sag) is a concern, there is really only one time to decide to err on the side of conservatism and go with a thicker panel – before you make the investment! Model #OSB5848ZRT. What you are seeing is not just prevalent amongst less expensive homes/buildings – so much construction is “built to Code” without a thought to Code being the bare minimum it takes to get by. The industry’s most comprehensive post frame blog. or Table 9.23.15.7.B. Because the APA – the Engineered Wood Association – creates labels for every piece of lumber they certify, OSB or plywood. “My pole building is going to have asphalt shingles. Sheathing is not meant to be a moisture barrier or vapor barrier primarily. There has been a lot of mis-quoting of the wrong section of the code. It is true as the price of every OSB board is around $15 – $20 per sheet (4×8 sizes). Sheathing a shed roof is no different. For areas with extreme snow, look for panels that have total loads of 50 psf – pounds per square foot. Standard roof sheathing thickness is ½” to ⅝” thick. Another consideration is if your rafter or truss spacing allows you to place your sheathing – usually 4’x8’ panels – so that each edge of the panel is supported. or Table 9.23.14.5.B. Unlike other materials, an OSB has a squarer and smaller dimension. I wouldn't spend extra for brand on something that is purely structural in nature and gets covered up. A staple in a wide range of construction projects, OSB board is used for everything for sheeting through to structural sheathing and more. The strands, which are compressed and bonded form like a plywood in three or five layers and waxed to ensure waterproofing. Even in your neighborhood you’ll notice homes with roofing that sags. Sheathing with a thickness of less than that is much more likely to result in bowing between framing which could potentially compromise your exterior roof material. Snow load should factor into your decision in terms of how thick your strand board or plywood will be beneath your exterior shingles or metal roof. Because OSB is made with wood, which will expand or contract when subjected to changes in temperature and relative If you opt to use screws, then #10 wood screws would work. My trusses are 10′ OC and purlins are 2′ OC with a 50# snow load. Call 866.200.9657 for a free consultation now! Of course these loads will only be experienced with a roof covered with snow, which means you are not able to see the sag. Why? It takes water longer to penetrate it, but once it gets into the sheet then it takes a much longer time to dry. One thing I noticed was that the entire house frame was covered in OSB – even the roof deck. I’ve seen a lot of random chit chat on forums about roof sag and such, but none of the posters seems to have any substance to back up their “guesses” about what is really adequate. Deflection is the dictate here – the IBC (International Building Code) allows for maximum deflection of a shingled roof to be l/180 for live plus dead loads or l/240 for live loads only. Save money by using a strand board, then use that savings to up the thickness a little bit. Handling large panels on a windy day while on a roof sometimes doesn’t end well. Comment below to have your question answered on a future episode! A homeowner recently wrote and asked me the following regarding OSB roof decking: Q. 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. You need to find a sheathing with a span rating of at least 32/16, which means either 15/32″ or 1/2″ thick OSB. Plywood dries much faster than OSB because it is not as dense. The choice of thicknesses actually varies widely depending on what store you shop at and where you are in North America. One of the difficult parts about figuring out roof coverings for your shed or house are all the options. For the curious – 7/16” OSB has a span rating of 24/16 and with supports every 24 inches is good for a roof live load of 40 psf (pounds per square foot) with a 10 psf dead load. In that case, strand board is best instead of plywood. My solution when I built our garage was trusses on 19.3 center (the Canadian std) and 5/8 osb. There’s No Education Like Real Life Business Experience, Used Motor Oil for Treating Pole Barn Posts, Pneumatic Vacuum Elevators for Barndominiums. For heavier loads – a 40/20 rated panel (19/32” or 5/8”) will support a 130 psf live load and 48/24 rated panels (23/32” or ¾”) are good to175 psf! thanks . The strand board, besides being cheaper, also works extremely well with tar paper. Thickness allowed depends on how far apart rafters or trusses are spaced and the rating of your roof decking. If you are using OSB for your roof deck, then ⅝” is the recommended thickness. The tables in the Code itself do not cover your live load, so a trip to the TECO® OSB Design and Application Guide tables is necessary. For plywood, which is slightly stronger than strand board, ½” thick is … In this case, you can’t use a 3/8 inch thick sheet. It is generally believed that OSB is cheaper than plywood. The typical thickness of roof sheathing is about 7/16-inch, which is just under 1/2-inch. Compare; Find My Store. Look at our collection of building photos for creative ideas! Thickness or Rating (1) The thickness or rating of roof sheathing on a flat roof used as a walking deck shall conform to either Table 9.23.14.5.A. Deflection is the dictate here – the IBC (International Building Code) allows for maximum deflection of a shingled roof to be l/180 for live plus dead loads or l/240 for live loads only. If that is the case, you’ll find that your framing can support thinner panels than if an edge does not sit directly above a framing member. Overall metal roofs use less nails than asphalt shingle roofs, so you have fewer fasteners holding everything together. A thicker panel means less sagging and a stronger roof deck. For heavier loads – a 40/20 rated panel (19/32” or 5/8”) will support a 130 psf live load and 48/24 rated panels (23/32” or ¾”) are good to175 psf! The thickness of OSB is controlled the same way plywood is. There has been substantial debate over the minimum acceptable thickness of plywood when used as roof sheathing. Invented in 1963 by Armin Elmendorf in California, the OSB is the cheapest board used in roof decking. Remember to always use your fall protection when working on the roof. Therefore, there are many options available. That minimum number refers to either OSB or plywood. Beneath those numbers are the maximum allowable live and dead loads that panel can support. Because of its construction, some manufacturers actually make larger sheets of OSB. That is more than enough strength to keep the snow from falling into your structure. In the case of ceilings, boards between 18mm and 25mm thick usually deliver good results. Probably, but the key is not to sheath using the minimum thickness. I saw 7/16″ in Appendix VI in your guide, but wasn’t sure if that was adequate in my case. Most builder's use 7/16"osb with clips if a heavy roof covering applied or called for on plans. Not just that, but most an OSB is manufactured in different sizes. This got me thinking about how thick my roof sheathing thickness should be on the shed I built. R. Founded by J.A.Hansen, Hansen Pole Buildings, LLC, was formed as a limited liability corporation in 2002, as an internet-based business providing custom designed, high quality pole building kits at affordable prices. There are even different types of plywood of the same thickness that will be rated for different spans, so it is critical to pay attention to the labels on the actual panel. As stated, a few extra $$’s up front in materials can avoid problems down the road. For the curious – 7/16” OSB has a span rating of 24/16 and with supports every 24 inches is good for a roof live load of 40 psf (pounds per square foot) with a 10 psf dead load. For instance, there are ⅜” panels rated for 24” rafter spacing. You need to find a sheathing with a span rating of at least 32/16, which means either 15/32″ or 1/2″ thick OSB. Both CDX plywood and OSB tend to come in standard sheets of four-foot by eight-foot (4×8). Save Share. A board that stays wet longer is prone to sagging, which is why strand board tends to sag over time on many homes. Strand board that is tongue and groove makes for a very straightforward install on your shed. When it comes to sheathing your roof, however, it never hurts to go thicker. When it comes to choosing a thickness for the solid decking to put atop your framing on your shed or home, one of the primary considerations should be the weather. Most roofs are spaced at least 20 inches apart. Multiply the length of the roof in feet by the width of the roof in feet to find the area of the roof … OSB is the better option for roof decking because it is cheaper and comes in a wider variety of larger sizes than plywood. A good alternative to ply-wood and usually cheaper, we stock OSB3 board in a selection of sizes. Around here, southern MN/The Cities, you can drive through the neighborhoods with cheaper houses, the ones with trusses on 24 centers and 1/2 or 7/16 sheeting, and most/many will have sagged roofs. I know how much you dislike shingles vs a metal roof, but the garage needs to match the house. Osb Thickness For Roof. The tables in the Code itself do not cover your live load, so a trip to the TECO® OSB Design and Application Guide tables is necessary. Find the Area of a Roof. We supply trade quality DIY and home improvement products at great low prices ... Thickness. Standard dimensions are nominal 4 feet by 8 feet. Not all thickness are readily available. For plywood, it is like $5 to $10 more expensive. 18 mm (1) Filter products. Roof sheathing is one area where it pays to spend a little more money. Therefore if you pick up some ⅜” sheathing that is 12/0, that means the max gap it can bridge between rafters or trusses is 12”. You could always opt for thicker roof deck panels, but for a shed there is no need to go thicker if your framing is of standard width. Your email address will not be published. And while plywood may dry faster than strand board, it’s important to note that all strand board roof decking you buy these days has blue edges. This comes as a surprise to many consumers because OSB looks simply as if lots of pieces of wood were glued together. Will thicker sheathing help mitigate that problem? The oriented strand board (OSB)—This board type of layers and strands of wood, adhered together to form a board. 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. The label clearly states maximum spans and loads allowed for that piece of roof substrate. Roof decking that will have metal for its outer roof covering is no different than sheathing a roof that will have asphalt shingles. However, you might find that OSB can better suit your needs than plywood for the roof. 19. 8 Tips For Getting The Best Out Of Your Oriented Strand Board Osb. 18mm was initially chosen for its strength. Therefore you’ll want to ensure you have the most solid substrate possible for that metal roof to screw into. With this thickness any deflection under dead loads only (the weight of materials only) should prove to be imperceptible. When installing sheathing, use 8d roofing nails. OSB is widely used as roof decking material. This guru will grant you the answer to one pole barn question! Less bowing means a more secure surface for roofing material, improving the longevity of your roof. That, in a nutshell, is the one big advantage plywood holds over OSB. Eugene has been a DIY enthusiast for most of his life and especially loves being creative while inspiring creativity in others. OSB is so strong in fact that it is now used for about 70% of all floor, wall and roof sheathing in North America and there are two different types of OSB, OSB2 and OSB3. If you are considering battens in place of a solid substrate, just know that strand board or ply acts as a noise barrier as well as a secondary moisture and temperature barrier. He is passionately interested in home improvement, renovation and woodworking. The thickness required by Josh’s circumstances are good for roof snow loads of up to 70 psf (again spanning 24”). Another factor is how far apart your trusses or rafters are spaced. 24” and 16” are the most common spacing, and you’ll often find 16” standard for rafters and 24” standard for trusses. Check with suppliers to determine availability. OSB comes in 4-by-8-foot sheets, as does plywood, but the manufacturing process allows the production of longer and wider ones. However, there are some sceptics out there who doubt the strength and durability of OSB. Thus, for sheathing a roof with metal panels, you’ll want to stick to ⅝” panels. OSB will not absorb water easily, but when it does, it takes a long time to lose that water and dry out. Tables to aid in properly dimensioning SWISS KRONO OSB products are available on our website. There is no upper limit on how thick your roof substrate is. It is important to note that there is no “standard” sheathing thickness, at least officially. The most common uses are as sheathing in walls, flooring, and roof decking. OSB board is preferable to plywood for sheathing a shed. Of course, some shed owners, or homeowners, may opt to use battens in conjunction with their metal roof, but battens don’t offer nearly the amount of protection that strand board or ply does. With edge … Oriented Strand Board, commonly referred to as OSB, is a type of engineered lumber similar to particle board, formed by adding adhesives and then compressing layers of wood strands. Your email address will not be published. The thickness required by Josh’s circumstances are good for roof snow loads of up to 70 psf (again spanning 24”). Keep in mind, these are the maximum allowable deflections – which means under a full design load you can expect to see a deflection (sag) between the purlins of over 1/8″. To find the amount of plywood needed to cover a roof start by finding the area of the roof. If you get ⅜” panels that say 24/0, it can span up to 24” between framing members. Installed correctly allowing falls to roof using per furring. You may see 3/8-inch plywood installed as roof sheathing and, although it may feel inadequate compared to 1/2-inch plywood installed on rafters spaced 24 inches on center, 3/8-inch plywood was, at one time, considered acceptable in some jurisdictions. Because of this, OSB struggles to revert back to its original state. You’ll find that the performance of the OSB will be more than adequate for your shed’s needs. Both plywood and oriented strand board (OSB) are equal in strength and durability. laid with staggered joints. My question is what thickness of OSB should I use? And if you are looking for a deal, it may pay to hesitate before you go cheap and purchase ⅜” panels. Greater distances and loads require thicker boards. Sort by: Wickes General Purpose OSB 3 Board - 9mm X 1200mm X 2400mm (391) £17. Talking about plywood or OSB for roofing, you cannot miss the information of the cost. It is most often OSB – a type of particle board – or plywood. for subfloors. Remember that ⅜ is very thin, and any load placed atop ⅜” panels will likely, over time, make the strand board or ply panels sag even if placed at the rafter/truss spans as designated by the panel label. Often you can see the outline of the rafters or trusses beneath the shingles. Dimensional lumber is not used because it would be much more expensive and provides a lesser surface for nails or screws due to gaps between all the boards. Typical types of wood used for roof sheathing are oriented strand board, known as OSB, and plywood, the most popular being OSB. The Hansen Buildings vision is to be the industry leader in post frame building kits as solutions to personal living, storage and agricultural needs while making great service a priority. Sheets of 7/16-inch thick, with no edge support, can be used in an area where the snow load is 30 pounds per square foot. Recommended Thickness of Shed Roof Sheathing, minimum requirement for roof sheathing is ⅜” thick, OSB (oriented strand board) – uses adhesives compressed with layers of wood chips that alternate direction between each layer, Plywood – compresses large, ultra-thin sheets of wood into a sandwich using adhesives and heat to form one board, Dimensional Lumber – an older way to sheath a house, in which tongue and groove lumber was frequently used or 1” lumber butting up against one another. Of course these loads will only be experienced with a roof covered with snow, which means you are not able to see the sag. Finally, if you are going to sheath a shed that isn’t heated, then OSB would definitely be a better option, provided you install the roofing material properly. The rough surface of OSB as compared to the smoother surface of plywood allows the tar paper to hold better and makes installation much faster. The recommended thickness for roof decking on a shed is ⅝”. ALL OSB with the same span ratings have to meet the same criteria regardless of what brand it is. There won’t be any condensation issues, so your roof deck is liable to stay dry. OSB / a sterling board . When you purchase roof decking, it will have an “APA” stamp with two numbers beneath, divided by a slash. If you are concerned about moisture getting into your sheathing, then plywood may be a better option. They are manufactured in both imperial and metric sizes, and are either square-edged or tongue-and-grooved on the long edges for panels 15 mm (19/32”) or thicker. You lose all of that if you opt for battens. OSB2 is great for structural, non-load bearing projects in dry conditions whereas OSB3 performs better for structural, load bearing use and for use in humid conditions. Buy great products from our OSB Category online at Wickes.co.uk. Reply. This makes it simpler for the consumer to pick out the right piece of product under their finished roof without having to worry about telling the difference between types of wood products. Make sure they are 1.5” long, which would work for ½” thick panels. Use in Roofs SWISS KRONO OSB is ideally suited as roof boarding. There’s a new house being built on my street and they’ve just finished up the framing and sheathing. Otherwise, no clips, just be sure to space all edges 1/8" as listed right on the sheathing (label), which goes down so the inspector can read it from inside (it's also the waxed side which is safer). Minimum sheathing requirements dictate that ⅜” thick is the lowest you can go in terms of thickness. (2) The thickness or rating of roof sheathing on a roof not used as a walking deck shall conform to either Table 9.23.15.7.A. The recommended thickness for roof sheathing is ⅝” thick. What is the Standard Roof Sheathing Thickness? Panel thickness will also affect permeability - using the 2 perm variable of 7/16ths OSB sheathing, at 3/4" thickness the permeability drops to 2/3rds of a perm. Originally, plywood was the go … Thicker panels will result in a more solid roof deck and resist bowing between the rafters or trusses. Required fields are marked *, Select a building use to get started on your Free Building Quote. What’s Better for Roofing: OSB or Plywood? If you are using OSB for your roof deck, then ⅝” is the recommended thickness. Sagging roofs are very common – and visible – and are easily rectified at the time of install. For plywood, which is slightly stronger than strand board, ½” thick is appropriate. Grademark-specified OSB panel thicknesses range from 1/4 inch to 1-1/4 inch. Plywood with similar properties currently costs about 30% more for an equivalent thickness. Oriented Strand Board (OSB) Sizes OSB panels are available in a variety of thicknesses and sizes. Dimensions include: OSB board 18mm; OSB … As mentioned above, all types of roof sheathing comes with a label that indicates spacing allowed between framing members. An 8d nail is 2.5” long and is more than enough to adequately fasten most thicknesses of roof substrate. to help guide you in the design of your new pole building. Thus not all sheathing was created equal. Roof deck materials to ensure a le roof decking material thickness georgia pacific blue ribbon osb sheathing oriented strand board osb vs building code for roof sheathing what you need to know about roof sheathing. The function of sheathing is to provide a smooth, flat, and solid surface for the roofing material to attach to with nails or screws. Dear Pole Barn Guru: Concrete Footing or Not? In the past, roof substrate was simply dimensional lumber but today’s options are cheaper and easier to install. double nailed at each joist. Once the area is known, divide by the area of a 4×8 sheet to find how much sheathing is needed. Finally, code requirements do not differentiate between types of roof decks. If your deck is thicker, then you’d want #12 wood screws at 2” long. The roof has no waviness/sag in it. Bob225 wrote:why waste ply on a roof unless its rough shuttering ply - 12mm WBP is perfectly fine - if your feeling really tight, OSB 3 (aka Stirling board) will do the trick I figured hardwood plywood would be a better choice since it's more substantial? For this, you can either go for a half inch or 5/8 inch thick sheet. The thickness required by Josh’s circumstances are good for roof snow loads of up to 70 psf (again spanning 24”). In this article, we’ll go over some tips for choosing the right sheathing thickness for your shed or house, including the types of substrate, techniques for installation, and what works best in different geographic areas. For the curious – 7/16” OSB has a span rating of 24/16 and with supports every 24 inches is good for a roof live load of 40 psf (pounds per square foot) with a 10 psf dead load. I'm halfway though sheeting the roof of my shipping container shop, and already need to redo some of it. A thicker panel may be required for 24” compared to 16”, so if you have larger gaps between the framing, consider a thicker substrate. Once the spacing hits 24 inches, a 5/8 inch thick sheet is more ideal. Adequate roof membrane showing solid thickness Mastic Asphalt 20mml / integrity using grade taken into consideration. Sufficient thickness 18mml . This makes the material perfect for roofing and other types of use! Oriented Strand Board (OSB) is an engineered wood structural panel created of strands of wood about 1 inch wide and up to 4 feet long. Using Oriented Strand Board is a tested way of reducing costs for building your shed. Popularity—which is used more? There are many different types of roof sheathing, the main ones are: Today the most common types of sheathing are plywood or strand board. The first number tells you the maximum distance that the panel can bridge between gaps. The minimum requirement for roof sheathing is ⅜” thick. You can have an OSB that’s larger than your plywood. I wish you luck on your roof project. Flexible Dimensions. Since there are so many layers in OSB it is somewhat heavier than plywood. OSB is a material with favorable mechanical properties that make it particularly suitable for load-bearing applications in construction. Even you have a ⅜” thick piece of strand board and the same for plywood, they may likely be rated for different spans. Standard roof sheathing thickness is ½” to ⅝” thick. Read More…. Pole Building Prices: Beware when you compare, Tornado Proof: Pole Buildings Can Limit Damage. It also serves as a secondary barrier between your house and the roofing material in keeping water out and heat in, to some extent. The adhesives that bond the strand board are also waterproof. If your rafters or shed trusses are widely spaced, or uneven (if it’s an old shed) then the tongue and groove give the edges additional strength, particularly if they aren’t supported by framing at every edge. … Keep in mind, these are the maximum allowable deflections – which means under a full design load you can expect to see a deflection (sag) between the purlins of over 1/8″. That means the edges have been waterproofed, which makes it much less likely water will penetrate the board. Looking forward to hearing your expertise on the subject.”. However, there IS a common reason to upgrade the thickness of the roof sheathing as explained above. At that thickness, you can economically sheath your shed while still getting an extremely solid roof substrate that will stand the test of time. You can use an OSB as a subfloor for sheathing, roof decking, and more! 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%. Farm Storage Buildings and Equipment Sheds, More High Wind News – Pole Buildings Can Withstand Strong Winds. The more wood chips there are, the thicker the OSB will be. Of course, nearly all frames are designed to fit roof sheathing edges, so when you install your panels you’ll be able to screw or nail your panel edges into the framing. Concrete Footing: How Thick Should it Be? What do you need to know when deciding between OSB and plywood for your roof deck? Roof sheathing is the solid surface below your exterior material, whether it’s shingles, metal, or another type of covering. The Ontario Building Code | Thickness or Rating 9.23.15.7.