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OSB Thickness for Walls: What Is the Best Thickness?

OSB is used in different types of things. This is engineered to be low cost and low maintenance and it is mainly made of shredded wood or wood-type fibers. These boards come in different sizes, and you can fit anywhere easily. 

What is the right thickness of OSB for a wall? Let’s find out.

OSB thickness for walls

Different OSB materials can be found in the market. The right thickness for two walls is 12 mm to 15 mm. The 12 mm thick OSBs are used when the supporting frame is 62.5 cm wide, and an 83.3 cm wide supporting frame is needed for 15 mm thick OSBs. OSB is the best sheathing material.

OSBs are a strong and good alternative to plywood. Though both of them are used as they last long, and these boards and sheets cost too little. Though some builders may say that the plywood sheets are more durable than OSB’s. 

Because some of the builders think OSBs are flimsy and can break apart after some time.

OSBs are the future for some builders as well. As these are thought to be a direct alternative to ordinary woods. It is not that costly to use OSB as sheathing material. From the 1950s till now, these boards are used. 

At present the OSB boards were not waterproof, now waterproof resins are used to glue the wood fragments together for a longer time.

As there is a debate between both OSBs and Plywood sheets, both these materials have similar durability and one can use both or one of them interchangeably. This flexibility makes these sheathing materials famous to everyone. 

You may need a 7/16 inches thick OSB or 5/16 inches thick OSB to guard your walls. 5/16 inches to 7/16 inches is the proper thickness for the OSB sheets and this thickness is perfect for the walls.

Rather than sheathing, you can use OSBs for floor underlayment, and covering the roof and you can use them in any sort of commercial or residential building. So, these are cost-effective, and anyone can use them. 

Everyone can work with these OSB boards, whether they are professional or not. 

For making walls, OSB is the best choice as they can provide multiple supports at the same time. As these boards are sturdy, they last longer and they can provide some structural support as well. The only problem with OSB boards is humidity and water. 

If these boards are soaked in water, then the board can expand and cause some breakages throughout the panel.

Shed walls: 

Shed walls provide some extra support to the roof. So, it needs to be sturdy enough to hold the leaning wall above it. Using OSB panels for shed walls will reduce the cost of the wall. 

OSB for the shed wall will reduce the cost by about 30% more than any other similar materials. Even plywood is considered to be costlier than OSB while you are making shed walls using them. 

Though people sometimes think that the OSB is less durable than plywood, both the OSB and plywood have the same durability. Before using OSB as shed walls, ensure you use waterproof OSBs, and the thickness is 7/16 inches for shed walls as well. 

Garage walls:

Garage walls need to be thick and in the cool areas, an external sheathing of 0.5 inches is needed. This is only possible when you have 10 inches of exterior walls of concrete. By maintaining all the codes for garage walls, you can use OSBs in the garage walls. 

Though there is a different level of garages, in the single-level garage the thickness of OSB is a little less than the double level. And all the supplementary goods added to the board also provide some thickness. 

Garden room walls:

In garden room walls, the thickness of the OSB is the same as in the general room. Just when you are preparing a garden room wall, ensure a ½ inches of sheathing. In cold areas, the temperature may fall so much, so you should have a better insulator. 

7/16 inches of the wall is perfect for garden room walls. The cost of making a garden room wall using OSB is cheap.

What is code for wall sheathing?

There are different codes for different building plans. The main purpose of building codes is to maintain safety and list particular rules and regulations for particular things. These codes set the standard for the law enforcement authority. 

If you can make the building or part of the building or any construction using the code, you are safe as well as the people who will directly be using these buildings or constructions. 

If a proper code is not maintained, then the law enforcement authority will show up and will not let you  use the property. So, you should maintain proper codes to conduct any construction. 

The code for external wall sheathing is 1304.13. This code is according to United States law. In other countries, this code may vary. When building something using the OSB, in the USA you should maintain code 1304.13 properly. 

Or the wall will not be going to be durable and will not last long.

Four factors that determine osb thickness for walls

There are a few factors that determine osb thickness for walls, some of them are given below –  

Placement of the OSB:

If the OSB is placed inside of the home, then you may need a certain type of OSB thickness and if you place it outside then you need to have a certain type of OSB. This is completely a subjective thing. 

Though the exterior OSB walls need to face more humidity and dust, so it is better to use waterproof OSB outside. And the proper thickness for the wall is 7/16 inches. So, you need to maintain this particular thickness and it is enough. 

Also, the supporting frame must be aligned as well.

The purpose these OSB are serving:

For walls, the thickness is 5/16 to 7/16 inches, but for roof and flooring, the thickness must vary. If you use OSB for roofing, then you need to maintain ½ inches to 5/8 inches thickness, for flooring 23/32 inches. 

So, when you are using these OSBs for making your wall, then you cannot use too thick or too thin OSB panels.


OSB is a good insulator. If you use OSB in winter-prone areas, then it will work properly. Because the temperature of the interior will remain the same while the outside temperature falls. 

Moreover, if you use thick OSB in high-temperature regions, then the room temperature will rise and stuck in. In an air-conditioned room, you can use thick OSBs.


Humidity or water is a great concern. If the OSBs are not made using water-resistant or waterproof material then there is a high chance of the OSB to suck humidity and expand in size. That will eventually cause the structure of the OSB to fall. 

So, it is important where you are placing the OSB.

How thick should OSB be for exterior walls? Is 7/16 OSB good?

An exterior wall is required to have 5/16 inches to 7/16 inches OSB. 5/16 inches is used to cover mainly the interior portion. The exterior portion should be covered with 7/16 inches of OSB.  These are the minimum requirements to cover the exterior walls. 

One can use a thicker OSB to cover the exterior section.

Thicker boards are better, as they can insulate more than thin boards. During the winter season, thick OSB boards can stop most of the cold. Plywood boards can be used as an alternative to OSB boards. OSB and plywood can be used interchangeably.

On the other hand, OSB boards are quite waterproof. If you can buy the better OSB then, it will highly likely be more waterproof and insulate more. In OSB, 90% to 95% is the shredded woods and 5% to 10% of them are strong adhesives. 

The adhesive here strongly attaches the woods together and makes the board lighter. For that reason, these boards are standard to use in the interior or exterior, and they are US APA standards as well.

Final Thoughts

OSB or Oriented Strand Board is made from wooden parts and is cheap as well. You can use them to make walls of any kind and you will get OSB of different thicknesses. The proper thickness for making walls is 5/16 inches to 7/16 inches. These boards have 95% of wood material and 5% adhesive.