Quote:
Originally Posted by fjmiller275
Update... have removed the skylight and the fantastic fan units from the top of the roof. After removing years of built up dicor self leveling sealant from each was able to lift them both off. I expected to find a curb under the skylight and I did but was surprised it was a one piece plastic molded/formed piece. As expected, there was no sealant or buytl tape under the flange of the curb that was fastened with screws to fiberglass roof with only 8 screws. My leak occurred because water was able to come under the flange and run down the side of the wood framed opening. I started removing the rotten frame that ran about 8 inches from the left side of the RV and about 6 inches of the left side starting at the front corner. The plywood backing to the interior fabric was rotten at least 3 to 9 inches back and I also had rotten plywood at the top of the styrofoam insulation just under the fiberglass roof. I have cut the styrofoam back and chisled and raked the rotted plywood. I can cut plywood shapes to replace most of the rotten plywood and will glue them to the styrofoam. I will replace the wood frame but it only serves to attach the interior plastic garnish since I have found that the screws on skyligjht frame are 2 1/8" away from the rough opening and the 3/4" thick frame is not part of making a securely fastened assembly. This is the main reason the curb get loose, especially if water gets under the curb frame and rots the plywood/luan roof deck.
I also will add at least 8 more screws to the original 8 used to fasten the curb.
On the fantastic vent, I will go back with a 2x4" wood frame and cut back the styrofoam to maintain the interior rough opening size. This small vent was attached with at least 14 screws but like the shower skylight, they did not penetrate the 3/4" frame since these screws were placed 7/8" from the rough opening which made them miss the wood by 1/8".
Missing butyl tape and inadequate wood blocking/backing for the frame were the root cause of my problem.
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I had the same problem with 2003 Dolphin LX. I was lucky not to have to replace rotten wood but after reinstalling the skylight I added EternaBond around the whole frame. Still leakproof after almost 4 years.
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