Best Sealant for Polycarbonate Skylights

Question

Question:

Is the alphathane 5121 compatible with polycarbonate skylights ?

asked by: Mike C

0

Expert Reply:

Hey Mike, thanks for reaching out!

The Alpha Systems AlphaThane 5121 Self-Leveling Sealant # AL35KV is designed for wood, metal, and glass materials. Since your skylights are polycarbonate I recommend using the Specialty Recreation Skylight Sealant # SR86RR instead because it is designed for polycarbonate skylights.

How many skylights are you needing to seal up?

expert reply by: Jon G

0

Jon G.

10/27/2025

Hey Mike, how did things go with the Specialty Recreation skylight sealant on your polycarbonate skylights? Your update could make it easier for the next person sealing similar skylights.

Reply

Mike C.

10/27/2025

@JonG oops sorry on last reply it showed up weird on my phone. I took it to a RV repair facility and had it fixed, I ran out of time. the people at Forest River told me i should use the alpha thane stuff which i knew had to be wrong since it didn't stick to the first sky light. Pretty Sad your year old travel trailer needs skylights replaced due to poor workmanship. Thanks for confirming, i have three tubes of the stuff you suggested that i will use for other reseal jobs in the future.

Reply

Jon G.

10/28/2025

@MikeC Glad to hear you were able to get it all working with the sealant we talked about! That is really frustrating though that your skylights started to act up after only a year.

Reply

Answer 1

Hey Shawn, the Curt Spyder adapter part #C35HR that you referenced has a 30k towing capacity. That's more than most gooseneck hitches as well as most fifth wheel hitches so I would say it has more capacity than you would end up needing.

view full answer...

Answer 2

To replace a skylight, you will follow the same installation as you would for a standard RV vent like #V2092SP-28. We do not have any skylight replacements available, but you will install a replacement using the Roof Vent Installation Kit - Sealant,…

view full answer...

Answer 3

The seal will push right on, but I would recommend using a few dots of adhesive to secure the seal in place. I would not recommend using a super glue, as it can melt plastics and weld things together. A few small dabs of silicone sealant would be…

view full answer...

Answer 4

Since your old trailer light only utilized one wire that means the one wire was used for power and the old light got it's ground through the mounting hardware. Since the new light like #MCL44AB has two wires, one for power and one for ground,…

view full answer...

Answer 5

Hey Ron! The etrailer Solar Expansion Kit #e72PR will work just as well as the #34282182 on your Jayco. There are a few differences in the specs but they're close enough it doesn't make a difference for this kind of setup. It is ok to mix…

view full answer...

Answer 6

If the camera is only getting 8.5 volts then you're dealing with a voltage drop issue. Furrion camera systems #FOS43TASF require 12 volts to properly operate and since you're having issues when towing the camera is most likely tied into a…

view full answer...

Answer 7

Hey Bob! Yes, the etrailer Solar Expansion Kit #e72PR can be used to add another solar panel to your Go Power Overlander #34282181 setup. You will also need the etrailer MC4 Expansion Branches #e92PR to hook up both panels. Are you installing this…

view full answer...

Answer 8

Hey Timothy, I reached out to my contact at Thetford and they said you need one of the following parts: - 42067 KIT, PEDAL HIGH WHITE STYLE II - 42078 KIT PEDAL LOW WHITE STYLE II These are made to order so you'll have to get it through them…

view full answer...

Answer 9

A good water heater to replace your Atwood GC6AA/10E 6-gallon heater is the Dometic RV Water Heater - Gas and Electric - Automatic Pilot #DMC74FR. Like your Atwood, this is a 6-gallon heater and requires a 12-3/4" tall x 12-3/4" wide x…

view full answer...

Answer 10

The Replacement Fan Motor Assembly Kit for Fan-Tastic Vent Roof Vent Fans #FVK8017-00 has the same hole spacing as the fan on your 6500 model so it will work. The diameter of the fan is a different than the original but it is the correct replacement.…

view full answer...

Answer 11

Hey Philip, yes the Specialty Recreation Low Profile Skylight w/ Inner Garnish and Sealant #SR56RR that you referenced will work great for you as it has a minimum roof thickness it can work with of 1-1/2 inch. This comes with the inner and outer…

view full answer...

Answer 12

Both the Alpha Systems 1021 Self-Leveling Sealant for RVs - White - 10.3oz - Qty 1 #AL98KV and the Alpha Systems AlphaThane 5121 Self-Leveling Sealant for RVs - Gray - 9.8oz - Qty 1 #AL45KV are good for use on TPO roofing and will allow you to…

view full answer...