I just finished replacing the Neo angle skylight on our 2004 Monaco Signature. Our original skylight had a few cracks and at some point dust and moisture had gotten in between the two panels.
Our skylight is two separate panels, an inner garnish with a clear rough texture and an outer tinted colored panel. I ordered replacement skylight panels from both Amazon and Camping World trying to find the correct panel combination. Most Monaco diesel coaches use a “Neo Angle” 30x13 skylight panel over the shower. The cutout measures 30” x 13”, but the panel itself is several inches larger with the flange. Specialty Recreation in southern CA makes many of these panels. Their smoke Neo Angle 30x13 panel runs about $200 from most places. Specialty Recreation also makes a white neo angle skylight inner garnish. I also found a much thicker/heavier clear Neo angle NSL30X13 panel made in Canada from Camping World (see first picture). I ended up not using the Specialty Recreation white inner garnish because combined with the tinted outer panel it allowed very little light into the coach. By chance the Specialty Recreation outer tinted panel had a 6” “bubble rise” and the heavier clear panel from Canada has a 4” bubble rise. These two panels fit together very well leaving a dead air gap between.
The next problem is removing the old sealant. At some point our panels had leaked on one corner and the previous owner cured it with lots of Dicor sealant. I used a chisel and small hammer to remove the old sealant. I placed the old sealant into a bag and all together there were several pounds of Dicor. Now you have access to the screws holding the panels onto the fiberglass roof. The old screws are #8 x 1” long hex head self-drilling stainless steel screws. For new screws, a friend pointed me to Allen’s Fasteners. They have these screws for 7 cents each (vs .50 cents each locally) and they ship USPS very reasonably.
With the old panels off, I now had to scrape and clean the fiberglass roof again so the new sealant has a clean surface to bond to. I used a spray can of Brake Clean (do not get any brake clean on your new Lexan panels!) and a rag along with a razor blade scraper to remove the sealant and butyl tape from the roof. This can be time consuming.
My original panels were installed with gray butyl tape, but it leaked on one corner so I did not want to use that again. At first I was going to use Eternabond to seal the panels to the roof, but after speaking to the folks at Specialty Recreation they recommended Surebond SB140. The solvents used in most of the other sealants attack the polycarbonate and they eventually crack. SB140 is safe for skylights.
I did a trial fit of the various panels and decided to combine the clear panel from Canada with the tinted panel from Specialty Recreation. I predrilled a few of the corner screw holes to make it easier to install the two panels later. (The original panel screw holes did not line up with either of the two new panel screw holes.) I first applied a wide bead of SB140 sealant to the fiberglass roof along the line of the screw holes making sure to fill the original holes also. I then installed the clear inner panel and lined it up with the previously drilled corner screw holes using a piece of thick wire. This is your last chance to clean the underside of the tinted panel and the upper side of the clear panel. I used liquid car wax to clean the panels. I then applied a thick bead of SB140 to the upper flange of the clear panel and installed the tinted outer panel. I then lined it up with the corner holes using a thick wire and began installing the screws. You know you are sealing it well when the sealant bulges out of the edges and also comes up through the screw holes. I added additional sealant to each screw head. It's not necessary to add more sealant to the edge of the panels.
Some tips I discovered:
Do not get any cleaning solvents on your skylight panels. Clean them with plastic cleaner or liquid car wax.
Make sure you use stainless steel screws.
Pre-drilling the corner holes really helps when you are doing the final install with sealant covering up the holes and trying to line everything up.
It would be nice to be able to use both panels from the Canadian company. They are much thicker and stronger. The challenge will be to make a gasket/spacer to go between the two in order to form an air gap.
Surebond SB140 sealant. I ordered 2 tubes but 1 was enough.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Specialty Recreation tinted skylight (I would order this from Camping World as it's less expensive)
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
#8 x 1” stainless steel hex head washer Tek screws
#8 STAINLESS STEEL HEX WASHER HEAD TEC SCREW