How To A Waterproof RV Slide Out [Explained]

RVs with slide outs are a great way to optimize the space inside, and once you stay in one you’ll never look back. But, how do you waterproof RV slide outs?

The only problem with slide outs is that they can easily leak and the seals are the most common areas for water to get in. This is because the seals are moved a lot when the slide out is extended and retracted, they can get warped and twisted out of shape and will eventually let water in.

If you own an RV with slide outs then you will need to know how to waterproof an RV slide out, so I have put together this article to help you.

Types of RV Slide Out Seals

The seals will be the area where the water is coming in from, so keeping them in a good condition will help to prevent leaks. I’ll discuss how to properly maintain your RV slide out seals later in the article.

The first thing you will need to figure out is what type of seals you have on your slide out. The type of seal will largely depend on the manufacturer, so it should be in the RV manual.

The two main types of fixings for slide out seals are push on, adhesive backing or glued on.

You are most likely going to have a combination of wiper and bulb seals. The wiper seals extend in and out over the seams of the slide out to stop the water getting in. Bulb seals prevent water getting in when the slide is closed by compressing against the slide when it’s closed.

How To Waterproof An RV Slide Out

Now that you are aware that there are different types of RV slide out seals, we can look at how to make them waterproof.

How to Waterproof an Existing RV Slide Out Seal

If your seals are in a fairly good condition and you don’t need to replace your RV slide out seals then you can reseal them.

Remove the seal and clean behind the area. Replace any fixings like screws if they need replacing. Give the seal a good clean whilst it’s un-attached.

Place a line of non-leveling sealant on the back of the seal and reattach it to the original position. 

Finish the seal off by using the sealant to fill in any gaps to get a completely watertight seal. If you are struggling to find the right sealant to use this guide on RV caulk will point you in the right direction.

Hopefully this goes without saying but do this on a dry day 🙂 

How to Replace Your RV Slide Out Seals

If your seals are not in a good condition then it’s best to replace them to get a waterproof RV slide out. It’s not a difficult task and not too expensive either if you do it yourself. Before you get started you will need:

  • Adhesive remover
  • Scraper
  • Tape Measure
  • Screwdriver
  • Glue (if new seals are glued on)
  • Sop and water
  • Cloths to clean the area
  • New seal (I will detail this below)

1. Get the right replacement seal

The easiest way to identify the seals that you have on your slide out is to look at them closely, from underneath if possible. The important part of the seal is the profile or cross section of it. 

The profile of the seal will ensure that the fit is watertight, you should be able to find a match for the profile from this catalog page, to make it easier you can enter your RV make and model for suggested seals.

Don’t forget about the bulb seal as this can be less visible than the wiper seal but it’s just as important.

Before you order the replacement seal you will need to know what length to get, use a tape measure to get the footage of the seal needed. Get an extra few inches just in case.

Make sure that you also measure the length of the wiper seal to ensure it will be long enough to seal the slide out.

2. Remove the existing seal

Your next step will be to remove the seal that you want to replace. The first thing you want to do is to lay masking tape along the edge of the old seals. The masking tape will be a guide to install the new seals and will also protect your RVs paint.

You can now carefully remove the old damaged seals, you might need to use an adhesive remover to help. The new seal doesn’t have to be attached the same way that the old one is.

To remove a wiper seal use a screwdriver to remove any screws holding it down, these are usually at the top and bottom of the seal. You should be able to carefully pull it off the RV.

To remove a bulb seal use a screwdriver to remove any screws, they will likely be in the top corner of the slide out. When the screws are removed you should be able to thread the seal out through the hole at the bottom or side.

3. Clean the surfaces

Next you want to clean the surface where the new seals are going. Always make sure that you brush the top of the slide out first as there is always debris up there that will get in the way. 

Clean all the crevices to get all the debris that has got in over the years. 

Then use an adhesive cleaner and scraper to remove all the old adhesive. When you’ve removed as much of the old adhesive as possible, clean the area and the new seal with an alcohol wipe. It’s important to get the surface smooth and clean for the new seal to fix properly.

4. Install the new seals

RV slideout seals come with a variety of fixings like glue on, push on and adhesive back. The new seal doesn’t have to be fitted in the same way as the old one. 

Push on and adhesive back seals are self explanatory, just push into place, or peel the backing off and push into place. Remember to bear down hard on the seal so it stays put.

If you are glueing the new seal on, then spread a small bead and flatten it out with a scraper or popsicle stick so it covers the whole surface area. A thin bead goes a long way so don’t overdo it with the glue. Do the same on the back of the new seal.

When the glue has become tacky, spread another thin bead along one of the surfaces, either the RV or the seal.

Using the masking tape as a guide, apply the new seal to the RV, make sure that you leave an overlap at the ends so you can cut it to the right length.

How to Maintain Your RV Slide Out Seals

Now you should have a waterproof RV slide out, you’ll need to know how to maintain it to get the longest life possible from your seals.

Maintaining your rubber seals is difficult because a lot of products can break down the rubber over time. You want to keep your slide out seals lubricated for easy and flexible movement, but most products will not be good for your rubber seals. 

It turns out that it’s not the lubricant itself that breaks down the rubber, but the additives it contains. Unfortunately most lubricants will have the additives for a longer shelf life.

Luckily for you, I’ve been researching and found that you can lubricate and protect the rubber with … baby powder. All you need is some baby powder and a dry cloth. You can also use a lubricant that has a pump action rather than a spray as they have less additives.

Wash and clean your seals thoroughly before you start application. Then use the cloth to coat your seals with a thick layer of baby powder twice a year and this will help to keep them lubricated and protected against extreme weather.

Check there are no gaps in the seals whilst doing this, if there are any small ones you can use a dab of RV caulk to seal them up.

Common Slide Out Seal Problems and Solutions

There are a couple of common causes for RV slide outs to start leaking here are the problems and simple solutions for them.

  1. Debris

Parking under trees, or just camping in general will mean that leaves, twigs, dirt and debris can collect on the top of your RV slide out. When you retract and expand the slide out this debris can distort and snag the seals.

The easy solution for this is to sweep the roof of your slide out before retracting it. It will only take a couple of minutes to sweep all the debris off the roof and it’s well worth it.

  1. Drying out

After a year or so your seals will start to dry out, if they are not taken care of they can crack and tear.

Keep your seals well lubricated, do this twice a year for the best results. Make sure to check them carefully when doing this, for any damage.

  1. Weather damage

Your slide out seals are out facing the weather 24/7, unless you have indoor storage. The weather will expose them to extreme temperatures and UV damage, both of which will cause the seals to turn gray and eventually become brittle and crack.

Unfortunately this is only a matter of time before this happens, but you can make your seals last longer with regular cleaning and lubrication.

Waterproof RV Slide Out – Final Thoughts

Waterproofing RV slide outs isn’t as difficult as you think, it will only take half a day to replace your seals and a few hours to maintain them. 

It’s important to do regular maintenance on your slide out seals to keep them in good condition and your rig waterproof. It also helps to keep insects, mice and debris from sneaking in through the gaps.

Your RVs slide out seals get a lot of hammer so make sure that you give them some love back.

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