How do you remove glued moldings

Secure two sections of the "floating" molding to each other and to the wall

I've added some comments for clarity on the solution. So I'll answer with some general options that you can combine or use individually depending on your solution. These are roughly sorted "from best to worst" for my preference for the best finished look.

  1. Remove and discard the piece on the left. If the wall behind it isn't flat, replace it with a flexible molding (i.e. flexible polyurethane molding). Secure it to the wall with construction glue and nails until the glue hardens.
  2. If the gap is too short, replace it with a piece of the correct size.
  3. If you can remove both pieces but also don't want to replace them, or if the options above don't sound ideal, remove both pieces. Assuming it's wood or some other material that holds screws in place, use a pocket screw or two on the back of the pieces to hold that seam tightly together. Reinstall it as if it were a single piece of molding.
  4. The simplest, but the ugliest: leave it as it is. Use paintable latex sealant to hide the seam. Then paint.

Edited to add based on your edit above: If you don't want to remove the pieces, there is not much you can do. Construction glue (common brand: Liquid Nails) can hold it in place, but it will be difficult to get in there without removing the part from the wall. With that part removed, you could build a drywall anchor into the wall and then hold the piece in place with a trim screw. You mentioned that the trim is mdf which doesn't hold the fasteners well. Hence, the idea of ​​the pocket screw is not known (although it would also require the pieces to be removed from the wall.)

In short, without removing or replacing the pieces, there might not be much to do other than try your best to hide them with painter's caulk.

Bill Bell

As is often the case on these websites, the OP does not think to mention what is obvious to him. So now I've marked it as "most important".

Bill Bell

Also, belated thanks for helping me clear up my question.

Dwizum

The clarifications were useful - I'm curious to see if there are any other creative ideas. It seems like battling with siding (and other square / straight materials) is a constant battle in older homes where nothing stays true / flat / square.

Bill Bell

I used drywall anchors. Thanks for that. As I pulled on the longer part of the panel, it began to fall off. So much for my worries about breaking it. :) The two anchors could now be the most solid part of the house.