Hi Ho Folks
This is a bit long-winded, but I want to be complete with the details...
Near the end of August the local monsoons started and, about a week later, I discovered a heretofore unknown leak in my Trillium
. The dinette seat cushion (passenger side, relating to tow) was wet where it's curved back edge met the rear seat/wall junction. Closer inspection revealed water was coming from behind the ensolite wall material and pooling in the curve of the junction. I finally decided that since the rear window was a replacement job, it was the most likely culprit.
In the past the louvered window had been replaced by a single pane of glass. Once I pulled the plastic trim and started to remove screws (yesterday - the sun was out and it was nice again. An aside: Here in the Vancouver area, once the rain starts in late August - usually coincident with the local "fair", the Pacific National Exhibition, many of us expect not to see the sun until the coming July. Some years - and I'm hoping this is one of them - the weather unexpectedly clears giving hope that time remains to still do some "summer" things.) it was obvious from the rusty screws that water infiltration had taken place, especially at the lower corner of the window nearest where I'd found the inside water.
With the window our I was able to determine the plywood window "frame" was essentially solid with only that one corner showing very minor signs of water. (maybe it's a "new" leak - PO kept trailer under cover.) I elected to not replace the plywood - time will tell whether that was smart or not. (By the way, there were 44 screws in the frame of five different types, three different lengths, and two different head styles. Included were a couple of long ones that ran right through into the trailer interior.)
I replaced the window with the butyl putty tape (wow is it gooey stuff!) and the 44 screws (now stainless steel, and all the same). I got a reasonable "squish out" all the way around and all the screws gripped nicely one the loose fitting ones had their loose holes dealt with. I will follow up with an overlaying perimeter seam of butyl caulking compound for peace of mind.
Now the conundrum and where I need the benefit of this group's experience. As the two accompanying photos show, the PO had added 16 screws, through the aluminum pieces that form the outside restraints for the replacement glass. These screws project radially through the edges of the window frame into the edges of the plywood. Some of the screws actually did make it into the plywood, but in a few cases, they missed the plywood altogether and were sticking into the ensolite foam itself. None were actually visible from the inside of the trailer though.
I am not actually sure why these screws are even there in the first place. Surely the 44 perimeter frame screws hold the window frame in place securely. Perhaps the PO was worried about the strength of the "putty" actually holding the new pane in place against possible pressure differentials - the only guess I could come up with.
I do have 16 open holes into the interior of the trailer now. My first plan was to just stuff them with caulking and ignore the screws. I now think I will replace some or all of the screws (using brass because I couldn't find SS ones of the appropriate size and I don't think the strength difference is an issue in this application) and then place a "blob" of butyl caulking over their heads to prevent water ingress.
So here are the big questions: (finally!)
1. Will a decent blob of butyl over these screw heads do a better sealing job than the original skin of silicone sealer?
2. After adding the screws, would it be a good idea to fill the gaps between the aluminum window frame and the plywood reinforcing frame with one of the low expansion foam insulations (from the interior)? (will this actually seal well against water?)
3. Any better ideas on how to deal with these difficult to reliably seal holes to the interior of my trailer?
Images follow: (yea, I caught it... silicone, not silicon, not same/same)
P.S. I was even able to buy new plastic moulding (to cover the outside frame screws) at Meridian RV in PoCo despite being told by another local RV shop that such a thing was out of date and likely unavailable. I will likely shop at Meridian again.