The most popular material for constructing walls and ceilings is drywall. Interior walls can be finished with its huge, hard sheets. Drywall is long-lasting and relatively simple to install. As a result, it is found in many houses nowadays.
Conversely, OSB is a multipurpose engineered wood panel that can be utilized as I-joists, floor underlayment, roof covering, and wall sheathing.
One can question whether drywall can be installed over OSB given that these two materials are used in the same location.
Our conversation will center on this, and we’ll go over all you need to know about plasterboard installation over OSB.
Can Drywall Be Installed Over OSB?
Over OSB, drywall can be installed. Both DIY builders and professional contractors use it frequently. OSB at the back will provide stronger support for hanging drywall.
Installing drywall over OSB is possible, but there are significant dangers and issues involved. Let’s first discuss some reasons why you would want to install drywall over OSB before we examine these risks.
The following are some reasons why you might choose to install drywall over OSB:
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1. You like a drywall finish
The most frequent justification for putting drywall over OSB is to preserve the original material’s finish. We can all agree that the finish left by drywall is smooth and attractive. Consequently, you can hang drywall to alter the finish if you recently moved into a house with an OSB floor.
It’s far simpler to hang drywall over OSB than to take the OSB off and then screw the drywall to the joists.
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2. You Desire a Sturdier Wall
These days, hanging drywall straight to joists is a common procedure among builders. Because the walls don’t provide enough stability, some builders call these kinds of buildings doll houses. The OSB material is far more durable than drywall when it comes to toughness.
Your walls will be more sturdy and rigid if OSB is placed behind your drywall. You can lay drywall over OSB if you want to strengthen the walls’ or ceilings’ structural integrity. Additionally, OSB behind drywall facilitates drywall repair.
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3. You Want to Take Advantage of OSB’s Insulating Properties
OSB is a great insulator in addition to strengthening the structural integrity of your walls. When built correctly in a wall, OSB provides unparalleled airtightness and insulation.
As a result, your room will be significantly warmer and your energy costs will be lower. Installing drywall over OSB is something you should think about if you live in a chilly climate.
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4. You wish to raise your walls’ load-bearing capacity.
Increasing the load-bearing capacity of your walls is another reason to install drywall over OSB. Garages and commercial structures are primarily affected by this. Will you be putting heavy fixtures or hanging tools on the wall?
Certain tools or mounts may weigh too much for drywall to support. For this reason, adding an OSB board behind your wall will strengthen its ability to withstand structural loads. In this instance, the mounted items will be fastened to the studs behind the OSB by screwing them through the drywall.
You can gain all of these advantages by covering OSB with drywall. But there are a few danger factors you should be aware of.
What Dangers Come With Placing Drywall Over OSB?
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1. When exposed to moisture, OSB expands and contracts.
Compared to other wood products, OSB is not all that different. When utilized in high-moisture environments, it is nevertheless prone to expansion and contraction.
assuming that in a high-moisture area, like a kitchen or bathroom, drywall is installed over OSB. As the OSB expands, there’s a good possibility it will harm the drywall. Consequently, drywall failure occurs.
When installing drywall over OSB, you must be careful where you do it. The ideal location is a room with little to no moisture.
As an alternative, you might use water-resistant drywall rather than ordinary drywall. Green drywall is a prime example. Additionally, it is not a good idea to butt the drywall closely against the OSB. You should allow for some growth.
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2. OSB May Make Your Walls More Fire Hazardous
More materials will burn when OSB is added to your walls, increasing the risk of a fire. Similar to other wood materials, OSB is combustible.
There is no way to prevent this or find a way around it. It’s just something you have to remember.
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3. The OSB may develop mold.
Sandwiching OSB with drywall could make the ideal environment for mold growth if there is a lot of moisture seeping through the walls.
For this reason, I stress how crucial it is to use drywall instead of OSB in places with low moisture levels. You might not notice the mold developing on the OSB for years since the drywall will hide it.
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4. It Will Make Your Jambs Longer
Your window and door trim will be impacted, which is another disadvantage of covering OSB with drywall. The additional drywall sheet will increase the walls’ thickness. Consequently, you could need to take action regarding the door jambs.
Which Drywall Type Is Ideal for OSB Installation?
The conditions in that specific space will determine that. You are probably aware that drywall comes in a variety of forms.
You must assess the room’s moisture content if you intend to install it over OSB. For instance, take a shower.
You must use moisture-resistant drywall, like the green variety, if you wish to install drywall over OSB in an area with such high moisture levels. Investing in a waterproofing product like RedGard is also advised.
On the other hand, ordinary drywall will work perfectly if you are putting it on OSB in the bedroom or living room. You must choose the best type of drywall before starting this project.
Can Damaged OSB Be Covered by Drywall?
No, you shouldn’t. Only structurally sound surfaces should be used for drywall installation. The screws won’t hold, and the drywall may come off at any time, if the OSB you intend to lay it over is damp, spongy, or broken. It is extremely dangerous for homeowners and their families to install drywall over damaged OSB.
Replace the OSB with a new one if it is damaged. Or remove it and put the drywall without any OSB on the back, straight to the studs.
When installing drywall over OSB, which screws should I use?
The task can be completed with standard drywall screws. However, I would suggest using longer drywall screws to allow them to penetrate the OSB, studs, and drywall.
When you screw all three of these materials together, the surface will be more structurally sound. You can indicate the location of the studs for simpler screwing after the OSB is installed.
As an alternative, you could screw the OSB first, followed by the drywall. Due to the brittle nature of drywall, you must use the proper screws. Ordinary screws run the danger of breaking the drywall.
Why Are OSB Installed Behind Drywall by Some Builders?
In certain cases, OSB may be hidden under the drywall when you move into a new house. Additionally, you might wonder why builders put OSB under drywall.
Any one of the four previously mentioned factors could be the cause. But in your situation, the builder might be trying to construct a shear wall.
By providing additional structural support, OSB can help the walls withstand side-to-side stresses.
