How to waterproof siding repair?

Question

I have replaced some windows and bad trims. The new windows have different sizes so now I ran into few challenges.

If I put small pieces of siding to patch that area in red circle, (1) how do I "seal" in between the siding, and best with nice cosmetic fix? Another option is to replace the entire right side of the new window (but then I need to buy more sidings).

There were lots of places like below photos where the siding does not meet the trim completely. Some are 1/4" wide. (2) Do I just caulk it? What type of caulk is best for such gap?

The original trims oddly placed on top of siding as below. I need to cut back the sidings a bit and put new trims. (3) But do I need to wrap the corner with waterproof wrap or something? There are some water damage visible inside.

Answer 1

You have to chose between cosmetics and functionality. Either way you're still going to need some more siding.

Functionally, you need like 2 pieces worth and you could remove and then stagger the existing. Cosmetically, you'll need most of a box.

There's supposed to be a metal shim and caulking in between butt joints. Without entirely removing or prying away (can of worms) the siding at the corner, there's no way to waterproof it.

Super awesome exterior caulk is made by Vulkem. Which obviously works pretty well because it's known to the state of California to cause cancer, birth defects or other reproductive harm.