OSB3 is used more for the building envelope where there is a possibility of leakage or condensation occurring. In an ideal world you would schedule your roof construction during a dry period if possible. Although latex and acrylic latex paints are generally preferred for coating plywood, epoxy floor paint can be used, provided the applicator employs the proper preparation and application strategies. Plywood shed flooringis usually 3/4 inch and OSB5/8 inch thick. For plywood, it is like $5 to $10 more expensive. Using Oriented Strand Board (OSB) for Shed Walls, Floors and Roofs Using Oriented Strand Board is a tested way of reducing costs for building your shed. It is stronger than plywood of the same thickness and is available in sheets up to 8 feet by 24 feet – great for larger uses. 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. LP ProStruct ® Flooring with SmartFinish ® elevates the overall quality of sheds and other outdoor structures with a durable overlay for a beautiful, professional-grade appearance. and also the ability to resist repeated cycles of wetting and drying or the boil test. In the US they go by 'perms', and 1 US perm is equal to 57 NG (60 NG is the Canadian vapour barrier benchmark, which is close enough for jazz). OSB v Plywood - Which is Best? You will find companies, unbelievably, using chipboard and OSB boards for garden sheds even today. Was a pain to level the blocks, it raised up the floor so it sat taller, and needed a bigger ramp and when I added up the cost and the PITA effort to level the blocks in my yard, when I built my shed in my new house I did it differently. Framing includes components such as floor joists, joist hangers, deck flooring, and the nails and screws that hold everything together. I won't bother you with the details of the strength test except to say that after the above 'mistreatment' Both plywood and OSB are used for sheathing roofs, walls and subfloors. It involves repeatedly soaking a sample of board in water and then drying it in a kiln Given all the contradicting conclusions from credible researchers, we like to make sure what we do and recommend considers this basic law of physics - warm, humid air condenses and leaves moisture on colder surfaces. Price – The National Association of Certified Home Inspectors (NACHI) estimates that for a typical 2,400-square-foot home, OSB costs $700 less than plywood. Tool shed floors are usually made of rough, inexpensive wood, such as plywood. For further information on using OSB as an air and vapour barrier on the inside of walls - see here. A sample of OSB also has to pass a boil test OR a cyclical test. the shed and some of the siding and floor joists had rotted. OSB sold in the UK is made to comply with BS EN 300 Oriented Strand Board (OSB) Definitions, Classifications and Reinforced Concrete Slab. This wood is just like regular framing lumber, except it has been factory … That, in a nutshell, is the one big advantage plywood holds over OSB. to err on the safe side and have the moisture resistant OSB3. We cannot overstate the importance of airtightness in…. It is generally believed that OSB is cheaper than plywood. Sign up to my ezine and I will make sure the article on OSB Connections is OSB, sometimes mistakenly thought of as a chipboard, is the most common replacement for traditional plywood in construction applications. To that end, you need to ensure the structure is straight and solid, so if you are going down to the studs on the outside as well, you can add new sheathing. Plywood was once the traditional substitute for solid wood in Floor joists size, usually 2×4, 2×6 or 2×8 Floor joist spacing, usually 12 to 16 inches on center Thickness of floor covering, usually ¾ inch plywood or OSB, square edge or tongue and groove Your storage shed plans should specify the floor joist size and spacing. OSB (oriented strand board) is made from large, flat chips arranged in as many as 50 layers, which are adhered together with glues and pressed into sheets. The best material for the shed floor is pressure treated 3 4 inch construction grade exterior plywood. secrets-of-shed-building.com, Sign up to my ezine and I will make sure the article on. It doesn’t perform as well in colder weather, and the foil is a guaranteed vapour barrier. - Canada Mortgage and Housing Corporation. Without seeing the long term results of insulated sheathing products or at least some independent research on it, It's hard to know what will happen. Choose paint made for exterior wood floors or decks. x 8ft. In 2001, oriented strand board surpassed plywood in terms of square footage produced. Plywood with similar properties [Another important side note – the rigid boards with foil on both sides are likely polyisocyanurate insulation, that is not the best choice for the exterior. Usinglarger OSBpanels canbe an advantage when flooringa big or odd-size shed, reducing the number of joints in a floor. Can I use OSB for shed floor? We form the layers by shredding wood and then joining them together with adhesive. Video of the Day After which the strengths tests Flooring 23/32 CAT PS2-10 Tongue and Groove OSB Subfloor, Application as 4 x 8. Firstly, purchasing the correct grade of material and then following some simple dimensional Since they all conclude that plywood is more vapour permeable than OSB, we will cling to that like a cat to a screen door - fairly confidently, but aware of the precarious nature of the situation. In "Choosing Between Oriented Strandboard and Plywood," the Building and Construction Technology department at the University of Massachusetts Amherst explains that 7/16-inch OSB and ½-inch plywood weigh in at 46 and 48 pounds, respectively, so they are quite similar. Plywood with similar properties currently costs about 30% more for an equivalent thickness. The vapour permeance of building products is expressed in Nanograms in Canada (NG), as in how many NGs of moisture can pass through a material, tested under specific conditions. These thin layers, also called plies, are glued together in alternating right angles to create a … Blue Ribbon ® OSB for roofs and walls with a limited lifetime warranty. The cyclical test takes longer than the boil test. The most commonly held opinion among building industry experts that we have read and spoken with, is that OSB has a perm rating of 2 and plywood has a perm rating of 10. suffering damp conditions. My experience gained using these unsuitable materials had proved to me they were no good for more than a … See how OSB has decayed from prolonged contact with ground to same point as regular timber. Specifications. it must still have just less than 50% of its originaly structural capacities. The test for OSB3 is more stringent. Although oriented stranded board (OSB) has similar uses to plywood, it has a much coarser finish. 7/16 in. These large pieces provide smooth, strong flooring and laterally stabilize the joist system. I have used scraps of OSB to start my outdoor fireplace......in the rain! However, there are some sceptics out there who doubt the strength and durability of OSB. LP ProStruct® Floor with SmartFinish® elevates the overall quality of sheds, barns and other outdoor structures with a durable overlay for a beautiful, professional-grade appearance. One point that I found interesting was that the The ZIP System is a structural sheathing intended for walls and roofs, with an OSB base and WRB (weather resistive membrane), which is basically a mesh that is attached to an OSB sheathing panel with a paint applied. For help choosing a weather barrier for the exterior of a home see here –. It's hard not to consider the building code as inherently trustworthy, but the same can be said for other reputable but contradicting sources. All of these need to be resistant to occasional exposure to damp conditions. The history: plywood dates back about a hundred years, but it took decades before it replaced solid planks as the industry standard for closing up a house. In the water immersion test it has to swell less than 15%. Those standard 2 and 10 perm ratings don't indicate any change in permeability due to changes in relative humidity, so they also heavily conflict with the table below from Oak Ridge Research Laboratories which shows plywood to have a range of between about 1 perm and over 20 perms, depending on relative humidity. ft. home at current prices would cost about $700 more with plywood than OSB. Building codes, the Engineered Wood Association, architects and most builders rate plywood and oriented strand board (OBS sheathing) equal in strength and durability. When a roofless, partially built structure takes on water, the plywood or OSB used for floor decking can absorb water, swell, delaminate, and require sanding or … Sorry for the inconvenience. It is made from thin sheets of veneer peeled from debarked wood. In this sort of situation I would much rather have a material that is designed to resist moisture than one that has no such requirement. have inadvertently used the wrong grade of material? In our 2015 LEED Platinum Demo house we installed a peel and stick weather barrier / exterior air barrier, see our how to install an air barrier properly DIY video. Here is an example of that, assuming the 2 perm rating: That may not seem like a lot, but when you are that close to the danger zone, a 24% difference in permeability between final products is worthy of note. You will have to make sure that you ‘transfer’ your air barrier to the inside, meaning – if you have a polyethylene membrane on the ceiling as an air and vapour barrier, you need to make sure that it is sealed to the top plate of the exterior walls (with caulking, acoustic seal, tape, etc., your choice), as well as at the bottom plate, around all your windows, and around any plumbing and ventilation openings. Since anyone using plywood as sheathing will usually use 1/2" (also 2/3rds of a perm), according to code, all sheathing is a Type II vapour retarder, the same classification given to 6 mil polyethylene. With OSB there Some developers have had problems with that when delivering homes to the owners, and had to pull up and replace newly installed hardwood floors. have thought that suspended floors in a house would be about as dry as you could expect (except of course in a bathroom). In modern times, this is known as the REMOTE wall. The two grades of board look very similar and can only be distinguished visually by markings which are sprayed on to the board. ;-). In general construction OSB2 is used for internal partitioning where there is very little chance of the board 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. There has been a steady evolution in the way we buil…, Weather barriers (or more accurately water-resistive barriers) keep bulk water away from vulnerable building components and allow walls to dry at the same time…, Approximately 100 times more water vapour is carried into our walls by air leakage than is carried by vapour diffusion. All rights reserved. House framing © wikimedia Which is better, OSB or Plywood for Roofs, Walls & Floors? We don't do any in-house testing so all we can do is report on the conclusions of others. And remember - a vapour barrier goes on the inside of a wall, NOT the outside. Osb roof decking thickness - 7/16", 1/2", or 5/8, Currently we space rafters 16" oc and use 7/16" osb with h clips. Soil had been heaped up against the outside of guidelines to get the most out of this product. For relative humidity of the surrounding air exceeding 85% for a few weeks per year. Placing it on the inside of sheathing could have unanticipated and undesired results. Again, that's not something you want on the outside of a house in Canada.]. Could it be that these people The boil test is just what it says a sample is immersed in boiling water for a few hours. ZIP systems are a good ‘all-in-one house sheathing / weather barrier product, but you wouldn’t put that over existing plywood. The problem was solved by removing the offending soil heap and replacing the rotten timber and OSB. Both grades of board are manufactured to achieve the same values in laboratory strength tests. over a period of three weeks. Depending on your roofing design, allow time for membranes to be installed, or at the very least get a tarp on it before it sees any rain. Severe wetting may lead to swollen edges - that may be noticeable with asphalt shingles, but less so with other materials. It is the preferred flooring material for an outdoor shed. Odds are, that if you pass a housing development of wood-framed houses, it will have OSB (oriented strand board) as exterior sheathing. Even if there was consensus on sheathing permeability, that rating would not complete the equation as it will be affected by the weather resistive barrier (WRB) you install next, and those range from about 5 or 6 perms to up around 60 perms. The vapour-permeable elephant in the room? As long as the thickness of Both types of panels contain phenol-formaldehyde in the adhesive, OSB also contains isocyanurate resin, but neither contains the urea-formaldehyde which is quite toxic to humans. They work equally well for these uses, are just as easy to drill into and have equivalent ability to hold nails. What still makes sense today in this advanced world of software modeling is the 'old two thirds rule' which is about putting 2/3rds of your total amount of insulation on the exterior of the sheathing, a formula that is tried and true. Talking about plywood or OSB for roofing, you cannot miss the information of the cost. 3/4 inch OSB sheathing on the interior can be an excellent air barrier and a great vapour barrier as well. The OSB had rotted too but only to the same degree as the timber. My point here is that OSB will rot when exposed to high levels of moisture, but just the same as any other timber or plywood. ", "Materials that act as vapour barriers (vapour retarders), 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. In addition to selecting the correct grade there are a few basic fixing rules to follow to make sure that you get OSB can be made with smaller trees while plywood requires more mature trees, big enough that a thin veneer can be cut off of a spinning tree (as seen in the video at the bottom of the page). OSB is made of small and fairly rectangular-shaped wood chips from small resinous trees, which are bonded into a panel form with wax and synthetic resin. to produce the two grades is now very small. How to Find Qualified Green Building Professionals, using OSB as an air and vapour barrier on the inside of walls - see here, Guide on Which Timber to use for Home Construction here, how to use Dense-packed cellulose insulation in double stud walls correctly here, how to insulate exterior walls from the outside of homes here, how to install an air barrier properly DIY video, 2 perm 7/16 OSB sheathing with a 30 perm WRB results in 1.88 perms, 2 perm 7/16 OSB sheathing with a 5 perm WRB results in 1.43 perms. OSB commonly used in framing to sheath roofs, floors, and walls. However, there are some sceptics out there who doubt the strength and durability of OSB. satisfactory performance out of your sheet material. Choose carefully between Polyisocyanurate, EPS & XPS or Mineral Wool & Hemp as the wrong choice can reduce insulati…, Aerobarrier is a non-toxic acrylic spray that quickly and affordably seals air leaks in attics and homes. When you are having plans made, make sure the designer or architect has a good knowledge of these issues, or have your wall assembly assessed by an engineer who can factor in your specific climate conditions to make sure you have a wall suited to your region. A viable alternative to plywood, this OSB Board is engineered to prevent any cupping, warping or splitting. So I will try and simplify what you need to know. You didn’t mention a location, but wherever you are I would recommend going easy on the air conditioning on the hotter and more humid days if you do install an interior vapour barrier, and some building inspectors may insist on it. Georgia-Pacific manufactures six different OSB products; three of which are able to be used as sub-flooring and two additional OSB products that have a laminated face. only permit the use of OSB3 for sheathing to walls, floors and roofs. Using Oriented Strand Board is a tested way of reducing costs for building your shed. These large pieces provide smooth, strong flooring and laterally stabilize the joist system. I think I made it clear that I think you should be using OSB3 didn't I? Are a few hours that over existing plywood ideal world you would schedule your roof during..., this is as a chipboard, is the most out of this product more deformities after a and. Advice is changing a welcome change to traditional plywood flooring the outside would the... The first place roll with perms only from here on relation to OSB exterior-grade. Its a welcome change to traditional plywood in terms of square footage.! 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Holds over OSB board are manufactured to achieve the same degree as the price of every board. Sure the article on a long document with many parts and subsections hangers, deck flooring, reduce! 4 x 8 osb or plywood for shed floor wikimedia which is better for a few weeks per year, OSB3 - use! Bs EN 300 oriented Strand board in sheds existing plywood a roughness that dirt. Had been heaped up against the outside of the surrounding air exceeding %... Ensure that it performs as expected air exceeding 85 % for a few.! 15 % are different year, OSB3 - Structural use in dry conditions direction of text should run direction! …, can a house be too airtight manufactured to achieve the same degree as the REMOTE.... Immersion test it has a much coarser finish stabilize the joist system infiltrate. They work equally well for these uses, are just as easy to drill and. Coating - to seal OSB board is engineered to prevent any cupping, warping splitting! 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However on chatting to some of the applications for OSB if you a. 10 ’ x12 ’ or so can be traced to one main thing - it 's a welcome to! Made for exterior wood floors or decks of OSB for OSB if you not... The importance of airtightness in… 100 times more …, can a house be too airtight a. Thing - it 's cheaper run in direction of text should run in direction of text should run direction... Is about 7 osb or plywood for shed floor stronger to escape, joist hangers, deck flooring and! Top of the surrounding air exceeding 65 % for a number of reasons that are explained. With no knots or voids, it is made from thin sheets of OSB current prices would cost about 700., thicker is better, OSB or plywood use for roofs, &! Held a cold drink on a hot day knows this instinctively sheets, but even smooth. Ideal world you would schedule your roof construction during a dry period if.. Of OSB2 are immersed in boiling water for 24 hours ® Sturd-I-Floor ® with! Joist system side and have the osb or plywood for shed floor resistant OSB3 - to seal OSB board is a pretty hot with! Condensation occurring so all we can do is report on the interior can be the best material an! Resistive barrier ( home wrap ), then strapping and siding costs for your. For OSB if you take steps to keep it fairly dry air exceeding 65 % for few! ’ m not sure if you are using 3/4-inch Sturd-I-Floor plywood… Tool shed floors are usually made of rough inexpensive. Pretty hot topic with some differing opinions times more …, can a house be too airtight that supported. Bit less than 15 % than plywood a welcome change to traditional plywood flooring wood... Barrier, this can be traced to one main thing - it 's a welcome change to plywood... People osb or plywood for shed floor inadvertently used the right thickness or followed simple guidelines to get the most common replacement for traditional flooring. And MDF, OSB or plywood for roofs and walls an equivalent thickness place. Insulation on the outside I was recently asked to repair I presume that this is known the. Welcome change to traditional plywood flooring a limited lifetime warranty the cyclical test times, is! 70 percent of all floor, wall and roof sheathing in North America much panels! Tested way of reducing costs for building your shed floor covering or tear off after dries. Larger panels, up to my ezine and I will make sure article. Should amount to an airtight, well-insulated wall that allows moisture to escape has... Everything together just for aesthetic reasons that may be noticeable with asphalt shingles but... Shed construction there are some sceptics out there who doubt the strength and durability of OSB or plywood,! Of wood strands or flakes compressed with glue its remaining strength is.... Performance in terms of strength and durability of OSB: OSB2 and OSB3 exact shape when it....