How to Replace a Subfloor in Travel Trailer

How to Replace a Subfloor in Travel Trailer

Latest posts by Justin Caldwell (see all)

Replacing the subfloor in any camper can be a daunting task, but a step-by-step guide can make it a bit less overwhelming. This guide will explain how to replace a subfloor in travel trailer, so you don’t have to panic.

There’s not much worse than walking through your travel trailer, or any trailer for that matter, and feeling a soft spot on the floor. When your subfloor starts to give way like that, that typically means you have water damage, and it needs to be addressed soon.

What is a Subfloor?

A subfloor in any structure, whether it’s a trailer, a house, or a commercial building, is the layer of flooring that is under the floor you see. If you have vinyl, hardwood, laminate, tile, carpet, or some other type of flooring, there is a subfloor is under it.

It’s normally a layer of ¾-inch plywood and provides strength to support your weight. It’s a very strong layer unless it gets wet. Even with a small water leak, you can incur some serious damage if you don’t notice it soon enough.

Assessing the Damage

When you first discover you have a damaged subfloor, your initial instinct may be to take it to a repair shop. You’re more than welcome to have them give you a quote, but you’ll be looking at thousands of dollars to fix it. There’s no way around the high prices that these shops charge for repairs.

With a little time, work, and extra materials, you’ll be able to fix it yourself for a lot less. Don’t let the process intimidate you. It really isn’t hard.

The first and likely most important determination is whether it’s major or minor damage. It’s important to determine if you can simply repair a small section of the subfloor or if you need to replace the entire thing.

Minor Damage

Replace a Subfloor in Travel Trailer

Minor damage to a subfloor is caused by a small amount of water leaking onto the subfloor and catching it relatively soon. If you can catch it within a few months, your subfloor will still be firm enough to support weight, and the softness you feel is (hopefully) superficial.

A bigger leak could cause minor damage as well, as long as you catch it right away. If a pipe bursts and you turn the water supply off right away, it will likely only cause minor damage. You can dry this water up without further damage and may not even need to replace anything.

If your subfloor is weak but no longer wet, it may be that you had a leak at one time, it’s been fixed, and you never noticed the subfloor damage. If your floor hasn’t caved in on you yet, it’s probably minor damage.

Major Damage

Unfortunately, sometimes there’s major damage. This happens when water sits on the subfloor for a long time. If you don’t address it right away, it will begin to eat away at the plywood, make it mushy, and cause it to cave in. This is when major repairs or replacements are the only options.

Fixing Minor Damage

So you figured out that there is only minor damage, and now you need to fix it. Easy peasy, and I’m not lying. Just be sure to follow these steps carefully to ensure you do it right. It’ll take some time and elbow grease, but it’s not rocket science.

Find the Size of the Leak

You really can’t cut this part of the process short. Assess the damage thoroughly to ensure it really is minor. If the leak is under the dinette, couch, or bed, take everything apart and remove the flooring so you can get a good look.

Water always finds the path of least resistance, so it can creep into places like under cabinets, refrigerators, dressers, and just about everything else. You can’t assume that because the damage feels like it’s in the middle of the living room floor that it actually is only there.

Be sure you know exactly where the damage is so you can fix it right the first time. You don’t want to rip your flooring out more than once.

Stop the Leak

Hopefully, this is common sense. If you don’t stop the problem at the source, you can replace your subfloor all day long and still have a mushy subfloor a few months later. You have to find out where the water is coming from and stop it.

Fix the Floor

Fix the RV Floor

It really is as simple as that. Expose the subfloor and find a flooring putty to fix it. You don’t have to remove any of it because a flooring putty will re-level it, strengthen it, and waterproof it to a certain extent.

There are a lot of flooring putties on the market, but Donald Durham’s Rockhard Water Putty is excellent. It’s water-soluble, so it will work to seal the subfloor and prevent further damage. It’s easy to apply and should take care of most minor issues.

Even with major damage, you can still use this putty to fill in the gaps later and help to finish the repair job.

Fixing Major Damage

Major damage is a different animal. You have to completely remove what’s been damaged. There’s no way around it. It sounds scary, but you can do it if you have the right tools and the knowledge, which is to follow.

While you can replace small subfloor sections yourself, if more than 20% of your subfloor shows extensive damage, you need to consult a qualified repair person first. When your travel trailer has that much damage, the structural integrity of your rig is at risk.

Tools needed:

  • Circular saw
  • Jigsaw
  • Power drill
  • Tape measure
  • Pencil
  • Flooring screws
  • Flooring putty

Armed with these tools, you can begin to fix your subfloor. There’s always a chance you’ll need additional tools, but this is an excellent start.

Find the Joists

Once you assess the damage and how much of your subfloor you need to replace, you should find the joists that are closest to but outside of the area that’s been damaged. You need to fasten your new flooring to something, so find where the subfloor is secured by locating the existing screws.

You’ll have to cut a piece out of your floor that’s larger than you might expect to make sure you remove all of the damage and give the new flooring a place to grab.

Mark Off the Area

Mark the area where you want to remove the subfloor. It’s important to indicate a square area so you can screw in the new piece of the subfloor. Once you’ve marked it, measure it. You’ll need these measurements later when you cut a new piece to fit.

Unscrew the Subfloor

Unscrew the subfloor only in the area you’ll be cutting away. Even though your floor is damaged, It’s still attached to the joists, so you need to unscrew it to make it easier to remove once you cut it.

Use the Circular Saw

Set your circular saw to the depth of your subfloor. Subfloors can be of different thicknesses. Some are ½ inches deep, while others are ¾ inches. Start by setting the circular saw at ½ inch, and if that doesn’t quite sever the board, you can increase it later.

It’s easier to measure the depth of your subfloor if you have a section that’s already rotted through. If you don’t, you want to be cautious not to damage anything beneath the subfloor. You may encounter electrical components or ducting.

Clear Out the Subfloor

Fixing Major Damage

Cut the subfloor very carefully and then clear it out. If it has major damage, you may be pulling out handfuls of rotted wood, or it may all come out in one piece. Every situation is different.

Sometimes you can use a hammer to pry the subfloor up, but if you’re struggling to clear it, you can use a shop vac to tackle the small pieces that remain after removing the majority of it.

Replace Insulation

If your subfloor is damaged, it’s likely that the insulation underneath is as well. Insulation is easy to remove, and you can replace it with standard fiberglass insulation that you get from a local hardware store.

Cut a New Piece of the Subfloor

Use the measurements you took when you marked your damaged subfloor to remove it. If you forgot, you’ll need to measure the dimensions of the empty space now so you can cut a new piece to fit.

You can get plywood for your subfloor at any local home improvement or hardware store. You’ll need to get a new subfloor that’s the same thickness as your old subfloor, or your floor will be uneven. All you have to do is cut this new subfloor with the same dimensions as the piece you removed.

Secure the New Subfloor

Use your power drill and flooring screws to fasten the new subfloor to the floor joists. If you lay it in and it overlaps the subfloor that’s still intact, you’ll have to cut it down a bit further. If it’s too small, you’ll need to cut another new piece.

However, if there are a few gaps once you get it secured in place, don’t worry too much about it. You can fill those in later with flooring putty.

Seal the Subfloor

No matter how big the gap is between the old and the new subfloor, you’ll need to create a seam and seal it. Use your flooring putty to fill in these gaps. Donald Durham’s should level itself and make the seam watertight.

Preventing Further Damage

Preventing Further Damage

You can’t always prevent damage. It’s the nature of living in a travel trailer, whether part-time or full-time. However, you’ll soon realize that replacing your subfloor isn’t something you want to do all that often. There are several things you can do to prevent further damage.

Maintain Outer Door Seals

Rubber seals crack and break over time and in inclement weather. You always want to make sure that all of your outer doors, whether they’re the doors on the front of your trailer or basement doors, have fresh seals.

Check these seals every few months and replace them as needed to ensure that moisture can’t leak through. Your basement doors will have seals that lead inside, whether it looks like they do or not.

Check Sneaky Places

There are plenty of places that are hard to get to in a camper, but they’re the most likely to have leaks. Under the sink, shower, bed, refrigerator, and other hard-to-see areas are all culprits. Check these areas every 3-6 months and fix any issues promptly.

Test the Water Lines

You can find even the smallest water leak with a pressure test. Test the pressure in your water lines every 3-6 months as well, just to make sure there’s nothing of concern.


If you’re facing a subfloor replacement in a travel trailer, you may have some lingering concerns. These frequently asked questions will give you a better idea of whether it’s something you want to tackle on your own or not.

Question: What Can I Use for an RV Subfloor?

Answer: There are several different grades of plywood and OSB that you can use for RV applications. You’ll want to use APA-rated sheathing, but exposure 1 is generally well-suited for subfloors, walls, and roofs. Exterior sheathing is better suited for high moisture conditions.

Question: What is the Floor of a Travel Trailer Made Of?

Answer: Most travel trailers and RVs are made with particleboard subflooring. It’s sometimes called OSB, and you may also find plywood in your subfloor. The particleboard is made from wood chips and water-based glue. When these two components are pressed, they dry quickly and retain their shape.

Question: How Much Does it Cost to Replace a Camper Floor?

Answer: When you’re tasked with replacing your subfloor, the cost will vary based on what materials you need. If you rent all the tools and purchase new materials, it might cost a few hundred dollars.
However, if you already have all the tools on hand and you simply need to purchase putty, screws, and a piece of plywood, it could cost less than $100. It will cost quite a bit of your time either way.

Final Thoughts

Finding a damaged subfloor can be worrisome, but it doesn’t have to be intimidating. You can fix even major damage yourself, as long as it’s only in a small portion of your trailer. Just follow these simple steps to get it taken care of.

If you do it yourself, you’ll save a lot of money over taking it to a repair shop, but you can always consult a professional if necessary.

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