LY Front Cap to Side Joint

[cruzaire]

Hello all,
I joined the forum recently and have gained much information by searching.
Our Land Yacht is 30 foot 1995 year model we have had for about 9 years now.
I have been chasing water leaks and found leakage at the front cap roof to side above passenger side window.
Also along roof rain gutter caulking had pulled away above awning mount.
Removed trim as shown in photo 1 and found screws holding top of roof cap to some interior wood backing.
But they were spinning in place, obvious wood damage inside.
There were only a couple screws placed in between the the side and the roof cap in an apparent attempt
to hold the side to the wood backing photo 2.
Opened up interior and found significant damage to wood backing, totally deteriorated and flaking apart, photo 3.
This leak had been around a long time.
I made a new wood backing using the old pieces as template, photo 5.
The original wood backing was not connected to the aluminum framework above passenger side window, not even caulked.
It was glued to the inside of the outside wall (and yes, some ply came off with the remaining backing pieces, unavoidable).
I apologize for this long narrative, but wanted to bring the project details (whew).
Now for my questions.
I'm thinking to caulk the wood backing to the lower inside aluminum frame member but worry about flexibility when driving.
Any advice on this?
I think the outside side wall should be screwed thru the wall into the wood backing, common sense says this, but I worry about what the

original intent was by placing those screws in between the side wall and the top cap.
Any comments from those who have been there and done this?
What is the grey rubber caulking or sealant airstream used?
This stuff seems to really stick and flex.
Thanks in advance for any advice.
Photos are below.
Tim
P.S. Not sure if photos got into the post.
I'm new to posting on forums and will keep checking.

[92landyacht]

My 92 LY had similar damage so I understand where you're coming from. Personally I see no reason to do the interior calk to the frame but I don't see any issue with it either. I would bond the new boards directly to the outside fiberglass using your glue of choice (I used Gorilla Glue). Make sure that the surface is clean and clear of any deteriorated material.

As for the screws, you can screw through the fiberglass, but the big thing is to give that metal striping a sold material to bite into. It's that striping that covers the sealant and clamps the top end cap to the sides. I wouldn't use any screw locations that would penetrate the sides but not go through the calking material.

The material used to seal the seam is a butyl rubber tape. It looks like this:


Usually comes in 20 or 50' rolls and is pretty cheap. It comes in gray and black. Get it wide enough to cover the seam behind the metal strip and overlap each side by a little. Usually 3/4 or 1" wide is what I get. This stuff is great for around windows too. Just about anyplace that needs to be sealed and is clamped in place. Don't be too worried about any material that squishes out. Just use a X-acto knife or razor blade and cut the excess off once the metal strip screwed down.

The stuff is cheap and you can buy it online or any RV place. Camping world carries it and it's on sale: Butyl Tape 3/4"x30' - Dicor BT-1834-1 - Installation Tools & Supplies - Camping World

Here's a another place I've used:Butyl Rubber Tape - Flexible tacky adhesive Sealing Tape - PPL Motor Homes

[cruzaire]

Thanks for your advice, sorry I took so long, I work slow.
I did repairs per your advice, worked out well so far.
Now waiting to install new carpet and we can take a trip.
Regards,
Tim

[92landyacht]

Glad it worked out. Most leak repairs on these MHs are pretty straight forward as long as you can get it done before the damage gets too extensive.

Have a great trip.