Building a shed, garage, cabin, or house today can be expensive. One way to trim costs is to use oriented strand board (OSB) instead of plywood. OSB panels have become common for roof decking, wall sheathing, subflooring, stair treads, and even utility shelving. However, before you start loading up your truck or trailer, you may want to know how much does OSB weigh.
The weight of OSB depends on its thickness, length, and width. A 4’x8’ sheet can weigh from 25 lbs to 120 lbs or more based on its thickness. The thickness and weight determine its structural strength and how it is used in construction.
In this article, we’ll explain how much a sheet of OSB weighs, factors that contribute to its weight and provide a chart identifying the weight of different panel thicknesses. We’ll discuss how to calculate the weight of OSB panels by sheet, bundle, and how many sheets your truck or trailer can hold. We’ll even compare OSB weight with comparable plywood thicknesses too. Our goal is to provide you with the information you need for your building project.
- Why Is It Important to Know the Weight of OSB?
- What Factors Impact OSB Weight?
- How Much Does a Sheet of OSB Weight?
- OSB Weight Chart
- Weight of Pressure Treated Oriented Strand Board
- Weight of OSB per Square Foot
- OSB Weight Calculator
Why Is It Important to Know the Weight of OSB?
Oriented strand board is made of strips or strands of different wood species. The strands are dried and then soaked in a resin and wax adhesive before being oriented into opposing layers to obtain the desired thickness.
The thick, wet sheets are then pressed and heated until dry before being sanded, cut to size, and finished. The sheets are then bundled, wrapped, and shipped around the world. OSB panels are very dense and have no internal or external voids like plywood.
OSB is used today for structural purposes such as roof sheathing, floor decking, wall sheathing, and siding, as well as for joists and beam construction and many other purposes. Since it is being attached to framing members, it is important to know its weight to ensure the structural integrity isn’t compromised. Roof and floor loading is typically calculated by tributary area or per square foot, so understanding how much a sheet weighs is very helpful.
The weight of an OSB board is also useful when determining transportation to work sites and when lifting it to upper floors or the roof. Knowing the weight of a sheet of OSB makes it easier to calculate how many a half-ton truck can safely carry or a ladder lift can hoist at one time.
A skid-steer or forklift can easily lift a bundle onto joists, trusses, or rafters, but the framework may not be strong enough to hold the combined weight. So, it is important to know the weights and limits before starting.
What Factors Impact OSB Weight?
Oriented strand board weight is determined by a number of factors, like thickness and size. However, there are other factors such as the type of material used to make it, whether it is treated or untreated, and its density that also impact its weight. To better understand the impact of the factors, each is explained more fully below:
The thicker the sheet of OSB, the greater the amount of material used to form it, so the greater its weight. OSB panels are available in thicknesses that range from 1/4″ to 1-1/8” with a 4’x8’ panel weighing 26.61 lbs and 119.75 lbs respectively.
The thicknesses also determine its use too. Sheets of 7/16” or 1/2″ OSB are used for roof decking or wall sheathing, and 23/32” or 3/4” sheet is typically used for subflooring. However, the joist and rafter span can also affect the thickness requirements.
Standard OSB board dimensions are 4×8, 4×9, and 5×9, with 1/2 sheets of 2×8 or 4×4 or 1/4 sheets or smaller often available. Special orders can have sheets of 4×20, 5×20, 8×20, or longer. However, the weight makes the large panels difficult to maneuver, so they are not common requests for residential applications. The larger the OSB panel, the greater its weight.
OSB panels contain strands from different wood species and adhesive resins and wax. The strands are dried before being immersed in the adhesive to fully coat them. They are then oriented and combined to form the sheets. More strands and glue are used to form thicker panels. So, the amount of glue and strands used will affect OSB density and the sheet weights, as will the type of wood.
Treated vs. Untreated
Sheets of OSB are available in different treatments and finishes. The treatments protect the wood from rot, insects, moisture, and fire. OSB commonly has a smooth side and a rough side and is typically stamped to identify US APA and Canadian CSA 0325 performance-based standards.
The stamp identifies end use (1F, 2F, 1R, 2R, and W), span (16, 20, 24, 2, 40, and 48), exterior use, strength orientation or axis, and which face is down, as well as manufacturer and mill. Bond classification, Exterior, Exposure 1, sanded, unsanded, and touch sanded are also often included.
Oriented strand board comes in four classifications which can also affect weight. OSB-1 is for dry environment indoor use including furniture. OSB-2 is for dry environment structural use, OSB-3 is for structural use in humid environments, and OSB-4 offers high structural performance for humid environments. The type of bonding agent used affects moisture performance, strength, and use, as well as weight too.
Exposure 1 OSB can withstand exposure to moisture during the construction phase but not for prolonged periods or the edges may swell. Exterior OSB is near waterproof and is able to withstand exposure to inclement weather for extended periods. However, cuts need to be treated to prevent moisture intrusion which can cause swelling and flaking.
Oriented strand board is formed from 2” to 6” stands of softwood timber. The type of wood species affects the weight as different species have differing densities. Poplar, aspen, spruce, hemlock, fir, and pine are commonly used to manufacture OSB.
Poplar has a density of 350 to 500 lb/ft³, aspen 420 lb/ft³, spruce 480 to 780 lb/ft³, hemlock 500 lb/ft³, fir 430 lb/ft³, and pine between 350 and 850 lb/ft³ depending on the kind. The result is that OSB boards have a density between 37.5 lb/ft³, and 42.5 lb/ft³, for an average of 40 lb/ft³. So, the wood species can greatly impact OSB density and sheet weights.
How Much Does a Sheet of OSB Weight?
The weight of oriented strand board depends on its thickness, length, and width. It also depends on the species of wood used, the type of resin binding agent, and its density. OSB board is available in thicknesses of 1/4″ to 1-1/8”, widths of 4’, 5’, and 8’, and lengths of 8’ and 9’ being common but 20’ and 24’ or longer being available.
The average density of OSB is 40lb/ft³, which is the value typically used to calculate sheet weights. The weight of typical 4’x8’ sheet thicknesses commonly used in residential construction is identified below.
A 4×8 sheet of 7/16” OSB weighs approximately 46.57 pounds or 1.49 pounds per square foot. It can be used for roofs with maximum snow loads of 30psf or less on trusses or rafters spaced 16” O.C. or less. It can also be used for wall sheathing on studs spaced 24” O.C. or less.
OSB panels that are 1/2″x4’x8’ are about 53.22 pounds or 1.66 pounds per square foot. 1/2″ OSB is commonly used for roof sheathing when supported every 16” and where snow loads are 30psf or less. It is also often used for wall sheathing.
3/4″x4’x8’ sheets of OSB weigh around 79.83 pounds or 2.49 pounds per square foot. This thickness is typically used for subfloor sheathing on joists spaced up to 24” O.C. It is also often used to sheath roofs if trusses or rafters are at 24” centers or for heavier snow loads.
A 4’x8’ panel of 5/8” OSB has an average weight of 66.53 pounds or 2.08 pounds per square foot. It can be used for floor sheathing on joists spaced 16” O.C. or less, and for roof sheathing supported every 24” O.C. or less. However, roof use is conditional on snow loads.
OSB boards that are 19/32”x4’x8’ weigh about 63.2 pounds or 1.98 pounds per square foot. 19/32” can be used for roof sheathing on framing 24” O.C. or less, and for floors supported 16” O.C. or less. It is also often used for wall sheathing too. Much depends on loads and local codes.
OSB Weight Chart
Oriented strand board (OSB) is available in different thicknesses and sizes. The weight of a sheet depends greatly on its thickness, length, and width. The Chart below identifies the average weights of 4’x8’ OSB board based on its imperial and metric thickness.
It should be noted, though, that not all metric thicknesses are available in imperial or vise-versa, however, conversions have been made of commonly available sizes for comparison purposes.
|OSB Weight by Thickness
(Based on 4’x8’ dimensions and an average density of 40 lb/ft³ or 640 kg/m³)
Weight of Pressure Treated Oriented Strand Board
Pressure-treated lumber is typically immersed in a chemical solution and then pressurized to push the preservatives into the pores. The wood is then removed from the treatment chambers and will weigh almost double what it did before immersion. The lumber is then air-dried or kiln-dried but it will retain some chemical weight, so its treated weight will be slightly more than its untreated weight.
For example, an air-dried SYP 2×4 will weigh about 1.49 lbs per linear foot when air dried, 2.65 lbs freshly treated, and 1.5 lbs treated after drying. Similarly, a linear foot of SYP 2×6 will weigh 2.34 lbs air-dried, 4.17 lbs freshly treated, and 2.36 lbs treated after drying. So, for an 8-foot length, the increase is negligible.
The manufacturing process for oriented strand boards usually involves the immersion of the strands of wood into a resin and wax solution binding agent. So, the finished product is typically water resistant.
Pressure-treated OSB board commonly is immersed in a zinc-borate preservative to protect it from decay and insect damage. The chemical retention is approximately 0.42 lb/ft³, so the added weight will depend on the thickness of the OSB panel.
For example, a 4’x8’ sheet of 15/32” OSB weighs about 49.9 lbs, if pressure-treated it would weigh about 0.525 pounds more, or around 50.43 lbs. A similar 1/2″ sheet increases weight by 0.525 lbs and a 3/4” panel gains 0.84 lbs. So, the weight increase due to pressure treatment is marginal.
Weight of OSB per Square Foot
The thickness of a sheet of OSB determines its weight per square foot. Since a 4×8 sheet covers 32 square feet, dividing its weight by 32 will give its weight per square foot. A few simple calculations will identify the approximate weight per square foot of different OSB thicknesses.
The OSB Weight Chart above is helpful as it identifies different weights for various thicknesses of OSB. So, a 4×8 panel of OSB that is 1/4″ thick weighs 26.61 lb or 0.83 psf, a 1/2″ sheet weighs 53.22 lbs or 1.66 psf, and a 3/4” panel weighs 79.83 lbs or 2.49 psf.
OSB Weight Calculator
Another way to identify the weight of a piece or sheet of OSB is to use an online OSB weight calculator. The calculator we use functions in inches and permits the density to be adjusted depending on the type of OSB. Its default density is 0.0231 lb/in³ or 40 lb/ft³ which is the average for OSB.
The calculator is easy to operate. Just convert the length and width to inch denominations and the fractional thickness to a decimal. Input the values and press the ‘calculate’ button, and the calculator provides the weight. The length and width can even include whole numbers with fractions converted to decimals for more accuracy.
Is OSB Heavier Than Plywood
Plywood is made of layers of veneer peeled from logs known as peelers. Oriented strand board is made up of small strands cut from logs or timber that are often unsuited for dimensional lumber or plywood. As a result, OSB board has fewer soft spots or voids and is more uniform than plywood.
It is also less expensive and considered more environmentally friendly too. It should be noted, though, that comparable wood species, binding agents, density, moisture content, and thickness must be taken into account. Additionally, manufacturers’ specs on products also vary.
OSB has an average density of 40 lb/ft³ while plywood of similar wood species has an average density of 34.08 lb/ft³. So OSB is around 14% denser than comparable plywood panels. A 4’x8’ sheet of SPF 1/2″ plywood weighs approximately 48 lbs and a similar sheet of OSB 53.22 lbs – 5.22 lbs or almost 10% more.
A 3/4” plywood sheet weighs approximately 70.4 lbs while a similar sheet of OSB weighs 79.83 lbs – 9.43 lbs or about 12% more. So OSB is not only denser than plywood it also weighs more than a comparable sheet of plywood.
How Much Does a Bundle of OSB Weigh?
The number of sheets, coupled with their thickness determines the bundle weight. The net weight of a bundle ranges from 1790 lbs to 1835 lbs, or gross weight of 1856 lbs to 1906 lbs. The number of sheets per bundle can range from 11 sheets of 1-1/2” thick OSB boards to 68 pieces of 1/4″x4’x8’ OSB panels.
How Many Sheets of OSB Can My Truck Hold?
The number of OSB sheets a truck can carry depends on a variety of factors. The load rating for a truck is often identified on a sticker fastened to the inside frame of the driver’s door. So, depending on the make, model, manufacturer, year, and condition of the truck, the load limit will vary. Additionally, the maximum load rating is also identified on the sidewalls of tires.
Most light-duty trucks have tire loads ranging from ‘70’ to ‘110’ or 739 lbs to 2337 lbs. The tires may have a letter rating of ‘B’ (35 psi) to ’F’ (95 psi) instead, which identifies the number of plies as 4 through 12 as well as load capability.
The box or bed size of the truck also factors into the load capacity. A half-ton truck with an 8’ box evenly distributes the weight within the truck box and frame. A short box truck spreads the weight onto the tailgate or cantilevers it past the gate, which can raise the front of the truck and make steering interesting.
Another factor to consider is travel speed, distance, and road conditions. A slow trip on smooth roads, a fast highway run, or back roads full of potholes and wash-boarding can affect load capacity.
The thickness, length, and width of the OSB board being carried determine its weight. If transporting 4×8 sheets in a half-ton rated truck, the load limit is approximately 1000 pounds or half of a ton. That means 37 pieces of 1/4″ of 4’x8’ OSB, 25 at 3/8″, 19 at 1/2″, 15 at 5/8”, 12 at 3/4”, or 8 at 1-1/8” based on weight alone. It is not advisable to overload your truck or the repair costs or fines may exceed the value of the project.
Oriented strand board is a common feature in house construction, DIY projects, and even furniture. Whether sheathing a wall, floor, or roof or using it for some other project, it is helpful to know the weight of various thicknesses of OSB board.
Knowing the weight is important when calculating loads for structural applications or for transportation.
Hopefully, you have a better understanding of the weight of OSB and are ready for your next building project.