I have read of the need to re-seal windows due to eventual deterioration of the foam seal that Jayco uses. I re-sealed one window today, and learned a lot. I was pleased that there was no sign of a water leak, but my trailer is only about 6 months old. Here's what the hole looks like without the window installed:
The outside edge of the window flange had left a slight mark on the side of the trailer. Note the distance from that mark to the edge of the hole on this side (the left side) - about 1/2 inch; the corner of the putty knife is on that mark.
Note the distance from the flange mark on this side (the right side)- about 1/8 of an inch. So we have only 1/8 inch of surface contact using a seal that does not last to keep out water.
I wanted to get the window better centered in the hole than Jayco did to provide the maximum sealing surface all around the window. I marked the outside of the trailer with electrical tape placed 1/2 inch from the edge of the hole, like this:
I removed the old sealing foam and used 3/4" wide by 1/8" inch butyl rubber on the flange. I then centered the window inside the marks made by the electrical tape. Note the difference in the installation location when the window is centered:
After the butyl has set for a while and quits oozing, I'll put a cap on the top of the window of clear geocel caulking. I think that the vacuum bonded luan and foam sandwich that Jayco uses is a good way to construct a light, strong, somewhat insulated wall. But with this type of construction, if the windows leak there will be big, expensive problems. And using the sealing methods and installation carelessness that Jayco uses, eventually there will be a leak. Therefore, I'll be re-sealing all my windows soon.
There's lots of advice and information in forums... sometimes it is correct. For example, all of my posts are made by a political appointee who got the job as a reward for contributions to my diesel bill.
2011 Jayco 28.5RLS; 2008 Chevy Duramax; Pullrite Superglide Hitch