How To Replace an RV Skylight

TheRVgeeks Maintenance, Repair, Replacement 7 Comments

If your RV’s skylight is cracked or broken, or just old and cloudy, we’ll show you how easy it is to replace it with a brand new one. Access to your roof and a few tools are all it takes to get the job done.

April 11th marks exactly a decade of full-time RVing for us! We drove away from our “stick house” for the last time on April 11, 2003 and never looked back. Since just about any type of motorhome, 5th wheel or travel trailer might have a skylight, we’re celebrating our anniversary with a video that just about any RVer can use.

You’ll need a putty knife or two, a can of mineral spirits, a caulk gun loaded with SureBond SB140 butyl sealant, a screw gun, an old rag and a pair of nitrile gloves (mostly to protect your hands from the mineral spirits). Of course you’ll need a brand-new replacement skylight too. Also be sure to have some extra self-drilling screws on hand just in case, since there may be more screw holes in the new skylight than in the old one.

After using your putty knife to scrape away enough sealant to expose the screw heads, remove them all with your screw gun (you could do this by hand, but there are an awful lots of screws to remove and re-install). Then use your putty knife to cut the sealant holding the old skylight onto the roof. If you have a rubber roof (or “EPDM”), be extra careful not to accidentally cut it.

Once you’ve broken the old sealant all the way around the perimeter, the old skylight will lift right off. Then use your putty knife again to scrape up any excess sealant. Now use the mineral spirits on your old rag to clean off the remaining sealant. If you have a “catwalk” roughened roof surface like we do in some areas, you probably won’t be able to get all the old sealant off. As long as you remove the excess, don’t worry about getting it all. Also be sure to be very sparing with minerals spirits if you have a rubber roof, being careful not to soak the material.

Now apply a nice thick bead of SureBond SB-140 on top of the old screw holes all the way around, and place your new skylight down, wiggling it slightly to spread the new sealant into place. Install all of the screws, keeping in mind that it is unlikely that many (or any) of them will go back into the original holes. No worries… the old holes will be sealed and the self-drilling screws will make new ones. To avoid cracking the plastic, don’t over-tighten them.

The final step is a nice bead of sealant around the perimeter and over the screw heads, and voila: you have a brand new crystal clear skylight.

To remove the inside liner of your skylight, follow the steps in our video here:

Access the Inside of an RV Skylight


Featured & Related Products & Services:



We're handy RVers, not professional technicians. We're happy with the techniques and products we use, but be sure to confirm that all methods and materials you use are compatible with your equipment and abilities. Regardless of what we recommend, consult a professional if you're unsure about working on your RV. Any task you perform or product you purchase based on any information we provide is strictly at your own risk.

We sometimes receive products for evaluation at no cost, and The RVgeeks are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites. But our opinions are our own, you won’t pay an extra penny, and we only link to products we personally use, love and can recommend to friends with complete confidence.


Comments 7

  1. My existing sealant is cracked, otherwise everything is fine. Can I apply Specialty Recreation SR140 over the top of the existing like you do with the Dicor Lap Sealant? or do I have to remove all existing sealant around skylight and re-seal?

    1. Post
      Author

      Hi Randy! Assuming that your existing sealant is SB140, how bad is the cracking? Is it just small surface cracks? Or do they look deeper… and/or does it look like the sealant has pulled up from the roofing/skylight at all? If it’s just surface cracks, we’d probably leave it… or use some mineral spirits to (carefully) clean just the sealant, so you can get a better feel for its condition. But if it looks like the cracks are deeper than that, we’d remove, clean, and re-apply… since SB140 doesn’t flow like Dicor does, it likely won’t will the cracks very well, if at all. You could also consider sealing over it all with Eternabond tape… which will thoroughly seal the area, but will make any future repair or replacement more difficult, since the Eternabond is VERY hard to remove (you’d have to cut it and then install more over it). Hope this helps.

      1. it does, thanks. I’ll clean it and look at them more closely but I’m thinking the cracks are more surface. Can I use denatured alcohol as opposed to Mineral Spirits? Also, another question, but related,…..is there any difference between the Surebond SB140 and the Specialty Recreation SB140. The SR product says right on it that its provided to SR by Surebond. it has the same labeling indicating its butyl sealant for skylights. I can’t seem to find any info on the web or on the SR website about this.

        thanks again.

        1. Post
          Author

          Hi Randy. We think the Surebond SB140 and the Specialty Recreation SR140 are the same product… especially given the fact that the SR140 says it’s made by Surebond! From Surebond’s Technical Data Sheet for SB140 (http://surebond.com/tech_data_sheets/SB-140TDS.pdf), they only mention using mineral spirits to clean up when using the product, so we’re not sure if using denatured alcohol would be a problem. If you’re concerned, we’d recommend contacting the (or one of the) manufacturers to ask. It’s probably not a problem… but would hate to have you use it only to find out it degrades the sealant and makes the problem worse, not better.

  2. This is my next project. You made it look too easy. I do have a couple of questions. Did you need more than one tube of sealant? What length of self tapping screws did you use? The last thing I’m comfortable doing to my Mountaire is poking holes in the roof. Hence the question about the amount of sealant needed for this job.

    1. Post
      Author

      Hi Bob! We’d suggest having two tubes of skylights sealant on hand, as we recall having only one, and also recall having JUST enough! As far as screw length, we used the same screws that came out of the skylight, which were surprisingly long. Since you also have a Mountain Aire, we’re guessing your situation will be the same. If we were to be installing something in the roof where are no screws had been before, we would definitely skewed toward shorter. We think our roof structure is three-quarter inch plywood along with other layers, so it’s pretty thick. Obviously it can support the weight of a person walking on it, so it’s pretty robust. Those self drilling screws don’t have threads out of the very tip, which makes them longer, and also the threads need to reach through the fiberglass down into the wood, so expecting them to be about an inch to an inch and a quarter long should not be considered unusual. It’s all about sealing correctly, and checking in maintaining that sealant over the years to prevents water penetration.

We'd Love To Hear From You... Leave A Comment!

This site uses Akismet to reduce spam. Learn how your comment data is processed.