Plywood is one of the most often used construction materials. It is durable and can be used for a wide variety of purposes. Is it okay to put plywood over OBS?
Generally speaking, there isn’t a problem with applying plywood directly over OBS. It can be attached in place with nails or screws. There are a few potential problems since you are dealing with two different types of wood but for the most part, this double layer of wood will not be a problem.
One of the good points about installing plywood over OBS is the fact that you are doubling up on a material that is already strong. OBS, or oriented strand board, is a very strong type of material. It is made by compressing wood strands in layers with adhesives.
As we will discuss in this article, some of the problems that you may run into can dictate if you would want to do this under certain circumstances. It’s a good thing to consider this because it can make a difference in your choice.
Can You Put Plywood Over OSB? (How To)
One important factor to keep in mind when applying plywood over OBS is if you would use screws or nails. There are differences between the two, and it extends beyond just the tensile strength.
Since nails have a flush shaft without threads, they don’t tend to be as brittle. Screws may break and can even lose their grip but nails tend to hold in place for the long term.
Then again, there are some times when you may be screwing down through the OBS and into a floor joist or something else of a different type of material. In some construction scenarios, it may be better to use strong screws for this purpose and predrilled holes.
Regardless of whether you decide to use nails or screws, the fact that you are using plywood is of benefit. It’s a very strong material that can be used as an excellent subfloor for almost any other type of flooring. It can also be used in other areas of the home, including the roof deck, the attic, or even on the walls.
One other thing that we will consider at this time is safety. Regardless of whether you are talking about insulation, glass, or working with any other type of construction material, safety needs to be a priority.
Look at the project you are doing and see how it will be possible to apply the plywood over OBS and to do so as safely as possible. Consider every aspect of the project, from bringing the wood on-site to attaching it using screws or nails.
Some of the safety is going to fall on the personal protective equipment (PPE) that you are wearing. Safety glasses are always a good idea, but gloves and a face shield may be necessary under certain circumstances.
Let’s take a look at some of the potential problems associated with putting plywood over OBS. We will then take a look at the process so that you can do it properly.
Should You Put Plywood Over OSB?
Under most conditions, it is possible to attach plywood over OSB and you will not experience any problems. In fact, it is usually a good idea because it helps add strength to an already strong platform.
There are some instances, however, when you may experience problems applying plywood over OSB. These can cause difficulties over time and can even weaken the entire structure if you’re not careful. Consider these factors:
Moisture – When it comes to moisture absorption, plywood will absorb it much more quickly. It also tends to dry quickly. As a result, you may have different moisture levels in two sheets of wood that are above and below each other.
The problem with this is that you can have an issue with the shape of the wood and shifting. One may expand faster than the other, causing the screws and nails that are holding it together to lose their grip.
Rotting – Since OSB tends to hold on to moisture a lot longer than plywood, it may end up rotting underneath the plywood. This can be an issue because you may not recognize the fact that it is getting damaged over time.
This can be seen in any part of the home where moisture is present. It could be the subfloor of the bathroom or perhaps the subfloor in the basement. It is also commonly seen when plywood is put over OSB on the roof.
Of course, this isn’t always going to be a problem but if it is an issue, it is one that should be addressed as quickly as possible.
What Tools Do You Need To Put Plywood Over OSB?
Gather the following tools to put plywood over OSB. Once you have them ready, you can proceed with the project.
Buckets
Rags
Broom and Dust Pan
Shop Vac
Hammers
Nail Gun
Drill
Screws
Level
Straight Edge
Circular Saw
Sawhorses
Copyright protected content owner: ReadyToDIY.com and was initially posted on December 9, 2022.
Clamps
Chalk Line and Chalk
Safety Glasses
Kneepads
Dust Mask
What Preparations Do You Need To Put Plywood Over OSB?
When doing any type of construction project, it’s always good to get the preparation out of the way and to spend sufficient time doing so. The same is also true when applying plywood over OSB and after you prepare, you can be satisfied knowing that the job will last a lot longer.
The following are some of the considerations for preparing to put plywood over OSB:
Cleaning – Before you apply these two pieces of wood together, it’s important to clean the OSB. If the OSB has been down for quite some time, it may have gathered grease and grime that will need to be washed away.
In addition, any sawdust or other type of debris will have to be cleaned from the OSB before you put the plywood in place. It is important to consider this because the sawdust and other debris will have an impact on how well they stick together.
A broom and dustpan will be a good place to start but you may want to use a shop vac as well. In that way, you will actually be lifting the dirt and dust off of the OSB rather than just moving it around the floor.
Acclimate – This is a vital step that is often skipped. Before you apply plywood over OSB, it should be acclimated to the conditions in that environment.
As an example, if the plywood is being put over OSB in a room, you should bring the plywood into that room at least 3 days before the installation takes place. That will give the plywood plenty of time to acclimate to the room along with its temperature and moisture content.
You should also avoid doing any cuts until the acclamation process takes place. The plywood may contract or expand during this time, so you need to wait until it is reached its final shape before you make the cuts.
The same is also true if you are applying the plywood over OSB in an outdoor environment, such as on a roof.
How To Put Plywood Over OSB
Now that you have everything prepared, it’s time to actually put the plywood over OSB and attach it properly. Fortunately, this is a relatively easy process.
The easiest way to put plywood over OSB is to lay the first piece in position dry and then build around it. Make sure that you are not allowing the joints to line up with each other because that would weaken the structure.
Don’t use glue to attach the plywood to the OSB. You want to allow a little bit of shifting because, as we discussed, plywood and OSB handle moisture in different ways. Since OSB will expand further, you don’t want it to break the bond of glue.
The biggest decision you will have to make is if you are going to use screws or nails to hold things together. If you are simply attaching one to the other without going into the joists or studs, then screws may be a good choice. Otherwise, you can use a nail gun to nail down through both pieces and into the structure.
Putting plywood over OSB is a great way to hide some of the imperfections that may exist in the deck. These imperfections should be considered in advance, however, because any large problem should be addressed and cleaned up before the plywood goes in place.
Once the plywood has been attached to the OSB, you can immediately put the finished surface in place, regardless of whether it is a floor, wall, or roof. There is no need to wait for any additional time to pass before you finish the project.
Copyright article owner is ReadyToDiy.com for this article. This post was first published on December 9, 2022.
It is possible to put plywood over OSB as it will add to the strength of the structure. As long as it is put in place properly and attached with either nails or screws, it will help to make everything stronger.
Related Articles
Can You Put Plywood Over Insulation? (How To)
Can You Put Plywood Over Old Hardwood? (How To)
Can You Put Plywood Over Particle Board?
Can You Put Plywood Over Plank Subfloor? (How To)
ReadyToDIY is the owner of this article. This post was published on December 9, 2022.