OSB Floor Weight Limit

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If you are constructing a home or shed or working on renovations to your existing home, you might be considering the use of oriented strandboard, or OSB. Much like plywood, this material is strong and can be used for subfloors or single-layer floors, and OSB vs. plywood cost tends to be reasonably comparable. However, be sure you are familiar with its strength capabilities before you use it in your construction project.

Basics About OSB

OSB is very much like plywood, except instead of having thin strips or sections that are layered at 90-degree angles, OSB uses interlocking strands of wood that are between 3 and 4 inches in length and interlock at the same 90-degree angle. In most cases, OSB is sold in sections that are 4 feet by 8 feet. OSB sizes may vary, however.

OSB weight is usually a bit less than its plywood counterpart. 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. If you are using 3/4-inch Sturd-I-Floor plywood, however, that weighs 70 pounds, while a similar OSB weighs 80 pounds. Depending on your project, this may matter or not be of consequence.

When OSB gets wet, it expands more quickly around the perimeter than it does in the middle of the board. This means that it may cause problems if layered under thin coverings like asphalt roof shingles. These "ghost lines" are a problem known to many builders, but OSB continues to be popular since it is largely considered as effective as plywood.

OSB Floor Weight Limit

LP Building Corp provided an OSB Sheathing report that outlines the APA — The Engineered Wood Association panel's trademark ratings based on use and span. If you will be using OSB sheathing as roof panels, you should adhere to the following:

  • 3/8 OSB, 24/0 APA span rating, 30 psf allowable live load
  • 7/16 OSB, 24/16 APA span rating, 40 psf allowable live load
  • 15/32 OSB, 32/16 APA span rating, 70 psf allowable live load
  • 1/2 OSB, 32/16 APA span rating, 70 psf allowable live load
  • 19/32 OSB, 40/20 APA span rating, 130 psf allowable live load
  • 23/32 OSB, 48/24 APA span rating, 175 psf allowable live load
  • 1-1/8 OSB, 48 APA span rating, 290 psf allowable live load

If you will be using OSB that is structural 1 sheathing rated, the following APA panel trademark ratings should be used:

  • 3/8 OSB, 24/0 APA span rating, 30 psf allowable live load
  • 7/16 OSB, 24/16 APA span rating, 40 psf allowable live load
  • 15/32 OSB, 32/16 APA span rating, 70 psf allowable live load
  • 1/2 OSB, 32/16 APA span rating, 70 psf allowable live load

OSB vs. Particleboard

Are you wondering what the differences are with OSB versus particleboard? While OSB uses wood components and waterproof adhesives, particleboard is instead made of wood fragments like wood chips and pulp, and then mixed together with a synthetic resin or a binder. Particleboard is mechanically pressed into a sheet and is a type of fiberboard.

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Danielle Smyth is a writer and content marketer from upstate New York. She holds a Master of Science in Publishing from Pace University. She owns her own content marketing agency, Wordsmyth Creative Content Marketing (www.wordsmythcontent.com), and she enjoys writing home and DIY articles and blogs for clients in a variety of related industries. She also runs her own lifestyle blog, Sweet Frivolity (www.sweetfrivolity.com).

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