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Can You Use OSB for a Shed? (How To)

A shed has some special considerations such as space, and exposure to the elements. As a first time shed builder it’s hard to know what materials are suitable, and OSB is used for many different applications in the building industry. This article will be a full rundown of whether you can use OSB for a shed, let’s dig in.

OSB is fine to use for a shed. But, it should not be used on any parts of a shed where the OSB will be completely exposed to the elements. Or, where it will get wet. It’s recommended to use OSB as sheathing for the ceiling, roof and walls. As well as, for single-layer flooring, and the subfloor.

Wooden house shed

The reason is that although certain types of OSB are water resistant, they are not completely waterproof, and will swell or bow permanently when exposed to water consistently. With that said OSB is extremely popular, and used in almost all new homes and buildings. Below, I will explain if it’s the best option for the different ways it can be used to construct a shed, and how to use OSB for a shed.

Should You Use OSB for a Shed?

Wooden house shed

With the range of different materials out there, it’s a good idea to know where OSB fits compared to the other materials that can be used to build a shed. As well as, as any special considerations you need to be aware of, that could sway your decision one way or the other. So, below is a full rundown of whether you should use OSB for a shed.

Overall, you should use OSB for a shed. It is one of the best materials to use because it’s lighter than the other options, is typically cheaper, but has all the same properties. However, it can only be used as sheathing, and/or waterproofed so it won’t be exposed to moisture.

Some people state that OSB should be tested for its moisture content prior to installing it. However, you should only do this if your OSB has been left in a humid climate, or got wet when it was moved to where you are acclimating it. OSB should have a moisture content 16% or less.

When OSB is made it is shipping with a moisture content of between 2% to 8%. So, unless it got wet or your climate is very humid you shouldn’t need to be concerned with measuring its moisture content prior to installing it. But, if you suspect it may be a bit wet, or you know it got quite wet then you should measure it using a moisture meter.

As you may know sheathing is what is put underneath what you see on the outside of a building. For example, underneath a metal roof there is a rigid layer of some material to insulate a building. Otherwise there will only be the framing of the roof, and the metal attached on top.

OSB is one of the most common applications for this purpose. It’s also used to attach waterproof material to – called underlayment, which protects the underside of the roof from moisture. The same is true for walls where it can be used as a backing for siding – such as vinyl siding, or a stone veneer wall.

As well as, underlayment for flooring such as tiles. Various tests have been performed on OSB to identify what it’s suitable to be used for on buildings such as sheds. These have been performed by the Engineered Wood Association (APA), who provide standards for building materials, and they have recommended that it only be used for the following parts of a shed:

  • Subflooring
  • Wall, roof and ceiling-deck sheathing

The other main option is plywood but it’s heavier, and tends to cost more. At certain times, and in specific regions plywood may be cheaper due to supply and demand. Plywood and OSB are virtually identical except for plywood being a bit heavier.

So, if plywood is cheaper it’s best to buy it over OSB. However, typically OSB is cheaper. It can be used as the interior walls without being finished.

But, overall drywall looks far better. If you paint or plaster OSB it never looks good no matter how many layers/coats you apply. This has been shown in many Youtube videos where people have tried it.

Therefore, if you want to use OSB as the interior walls, and leave them unfinished, you’ll need to be OK with how it looks. As you may be aware, for showers there is a comprehensive waterproofing procedure that is followed to make a bathroom stall completely watertight. These are referred to as waterproofing systems, and have a range of steps.

Applying each waterproofing system requires specialist training which typically takes a day or two, and are provided by waterproofing system manufacturers. It is possible to use OSB on the exterior of a shed such as on the roof if it is waterproofed using one of these waterproofing systems.

However, it’s typically easier and looks better to use OSB as sheathing, and instead finish it. For example, with siding, or roofing.

What Preparations Do You Need to Use OSB for a Shed

Wooden house shed

There is a unique procedure used to make OSB, and it is made from different materials to the other building materials out there such as plywood and drywall. Therefore, below are all the preparatory steps you need to be aware of when using OSB for a shed.

In general, if it has been delivered from a region that has a significantly different climate to your shed, acclimate it to your climate in a dry place for 5 days, where it won’t come in contact with water.

Acclimating wood is a common practice when installing wood, and used for all types of wood not just OSB, such as for hardwood floors. Some sources state that it only needs to be acclimated for 2 days, but others say 5 days. 5 days is more conservative, and if you leave it that long you can be sure it’s fully acclimated.

After it has been installed by nailing it in place it needs to have a specific waterproofing method applied to it. The exact waterproofing method you use depends on where you are installing it. For:

  • Ceiling-deck – use waterproof underlayment
  • Walls – Plastic wrap

How to Use OSB for a Shed

Wooden house shed

OSB comes in generic sheets that can technically be used for virtually anything. For a shed, however, OSB has specific uses, and there are a few important things to know about how to use it. Below is a full rundown of everything you need to know about using OSB for a shed.

In general, use it as the subfloor, and/or, the wall, roof, and ceiling-deck sheathing. It’s nailed into the framing, and/or studs like a regular piece of wood. After that, apply waterproofing over it depending on what it’s used for, such as plastic wrap or underlayment, below are more specifics.

Exactly how to install it varies based on what you are using it for. There are a range of complex steps involved, and specific measurements you need to be aware of, such as how to position each sheet, and how many nails to use.

Copyright article owner is ReadyToDiy.com for this article. This post was first published on February 16, 2023.

It’s also worth contacting the building codes office for your jurisdiction to see what the specific requirements are for installing OSB so that it meets your local building codes.

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ReadyToDIY is the owner of this article. This post was published on February 16, 2023.

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