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How to Replace Fiberglass Siding On An RV

If there’s one thing experienced RV owners know, it’s that their RV’s siding can really take a beating. It is your first line of defence against all of the elements that being on the road can throw at you. It handles wind, rain, debris, sun, and everything in between. 

Most RV fiberglass sidings can last for quite some time. You’re likely to get many years of use out of your RV’s siding before it needs to be replaced. If it has sustained significant damage, or if you just need a refresh, the switch is possible. 

To replace fiberglass siding on an RV, you first need to remove the frames and the lights. Remove the old fiberglass siding in sections, and then identify the holes where the lights and frames were. Then you can install the new sheets of fiberglass. 

How To Replace Fiberglass Siding On An RV 

There are quite a few steps involved in replacing the siding on your RV. The first step is to remove the old siding to make way for the new one. 

Aluminum siding is much easier to remove than fiberglass. Because you are working with fiberglass, be sure to work carefully and not cut any corners in this process. You should also ensure that you are properly protected. Wear gloves, goggles, and a facemask. 

Step One: Measure 

You’ll need to be extra careful as you measure your RV. When you measure your RV to decipher the right amount of siding to buy, take the width of the frames into account. The frames need to be able to overlap on top of the siding itself. 

Measure the siding from frame to frame. To that measurement, add in 3 inches for every frame or S-lock that will cover the siding. If there’s no metal frame on top of the siding, use the S-locks as a waypoint for your measurements. 

To the S-lock measurements, you’ll only need to add 2 ½ inches. Once you’ve taken all of your measurements, you’re ready to move on to the next step. 

Step Two: Removing Frames And Lights 

First, remove all of the frames around the section you’re going to replace. You’ll see them outlining the body of your RV, and around windows. 

Next, if there are any lights in the area of your replacement, use a flathead screwdriver to carefully remove them. Set them aside somewhere they’ll be safe during the installation. With your screwdriver, pry out any staples that you find in the area as well. 

So that you can easily place everything back where it went, mark out the holes where the lights and hookups were. 

Step Three: Strip Old Siding 

Strip down the old siding. You’ll want to go all the way down to the 2 x 4 or 2 x 2 studs, depending on what your RV has. If any studs have sustained damage, either during the process or otherwise, replace them now. 

With sandpaper, either 60 or 80 grit, remove any old glue residue from the studs. If you have metal studs, roughing them up a bit will help you get a stronger ‘hold’. This will help a lot for the installation. 

If you have metal studs, wipe them down with an alcohol solvent. Then, give them another once-over with a glue primer or glue prep solution. Doing so will ensure a stronger, more reliable hold once you apply the fiberglass siding. 

Add your adhesive, and move forward to the next step. 

About Fiberglass Siding Glue

You cannot just use any industrial glue when you’re replacing the fiberglass siding in an RV. Remember that not only is fiberglass a finicky material, but it needs to be able to hold strong. The outside of your RV is susceptible to all of the outdoor elements. 

When choosing your adhesive, look for one that does not use any solvents or petroleum products. Those ingredients will decimate the foam insulation underneath the fiberglass. 

Before you begin the process, make sure your surface is extremely dry. Any moisture could mix with the adhesive and make it lose potency. 

Step Four: Begin Setting In Screws 

Lift the fiberglass sheets into place. You might need another set of hands to help you out with this and make sure everything is even. Begin inserting screws, starting at the center top and working outward. 

Pre-drill your holes when you place your screws. Because of this, it’s not advised to use self-tapping screws. Self tapping screws could lead to cracking in the body of your RV. 

About Screws For RV Siding 

The thing to be wary of when choosing screws for your RV siding is the depth of the frame. It needs to be able to reach deep enough into the frame to get a good hold. 

Thankfully, unlike staples, screws cannot work themselves out. Also unlike staples, if one pops out, you can easily put it back from whence it came. It will still have a nice, strong hold if you replace it. 

With many screws, you will have to pre-drill and countersink the heads. This will help the exterior of your RV have a nice, finished look.

Step Five: Apply Braces 

It is going to take some time for your fiberglass siding to fully adhere. So that you’re not holding it there for hours, you’ll want to apply braces to keep it in place. 

Working from top to bottom, apply braces every 2 feet. It will apply all of the pressure needed to keep the panels in place. These braces will also help the panels adhere. 

Let this sit overnight, or for at least 8 hours. 

Step Six: Shape The Windows 

Use a router to shape the fiberglass so that it fits around the windows. Pre-drill your holes and reinstall the screws to hold everything into place. Make sure all of the framing is overlapping correctly. 

Step Seven: Seal The Siding 

Sealing your fiberglass RV siding is crucial when you’re replacing it. You need to get a solid, waterproof seal to ensure that nothing is damaged. Water damage can lead to a massive repair bill, and is best avoided. 

Make sure the surface is clean so that the sealant bonds well with the RV. 

There are two different types of sealant that you’ll use when you replace fiberglass siding on your RV. One is made for roofs, while the other is for siding. Of course, you’ll want to have the latter. Make sure it is a brand that is non-leveling. 

To apply the sealant, you’ll need a decent caulking gun. Make sure it is one that does not clog easily, and that will evenly spread the sealant. 

While it’s possible to smooth the sealant out with your fingers, this is tricky. It’s true that your fingers can be extremely precise, you are risking getting cut on any edges. There are plenty of plastic scraper tools available that can save your fingers this fate. 

Step Eight: Wash And Final Sealant 

When you’re done with your sealant, wash the RV and let it dry. Make sure it’s entirely dry before you proceed. 

Apply one more thin bead of sealant to all of the seams. You’ll also want to apply sealant around the lights. This is especially important for protecting any electrical components that are nearby. 

How Much Does It Cost To Replace Fiberglass Siding On An RV? 

Aside from the costs of all of your materials, the price of replacing fiberglass siding on an RV can vary. The price of siding runs a wide gamut, but on average, fiberglass siding is about $15 USD per foot. 

However, this will also depend on how big your RV is. It will also be a matter of how much you’re replacing. If you’re only repairing a small section, you might just need $90 worth. 

But if you’re swapping out an entire side, that price will rise significantly. 


Replacing fiberglass siding on your RV is not a difficult process. It will take several hours, and is something you must undertake carefully. Measuring is extremely important in this project, as needing to stop and re-cut could cost you time and money. 

What really makes this project somewhat tricky is the finer details. Shaping the fiberglass to fit around the lights and other small details will take time. It will also require a careful hand. 

You’ll likely need another pair of hands to help you out with this. It’s always good to have help, especially when working with something as large as fiberglass siding. Be sure that you’re both well protected with goggles, gloves, and protective masks. 

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