jambe, can you see if there's any evidence of filled-in nail holes in the trim piece?

I'm wondering if the trim piece had been taken down earlier, the nails pulled out, the nail holes filled in, the piece repainted, and then they just set it atop the vertical pieces where you found it.

As long as you can get the peice to stay where it looks aesthetically correct while the construction glue is drying theres no reason you can't glue, unless you plan on doing pull-ups on it lol.

la_koala, you're right. There are filled holes. Why the heck the nuts bothered to pull the original fasteners and fill the holes before driving their huge stud nails into it I have no idea...

I'll just use some finish nails to reattach it! Thanks!

Glue is fine but if you can find the studs, mark them on the molding and drill a small pilot hole where you want the nails to be. This will avoid splitting the trim.

We've had to do the same thing with our trim issues, like around the windows in our upstairs bathroom. We had very little sash to nail to so we drilled pilot holes and then nailed the trim so we wouldn't split the exposed sash or the trim with the nail being at the edge. We wanted a relief to give the windows period character, with no damage.

I'm posting a link to our project. You will have to scroll through the photos because I'm being lazy. Good luck! It's very doable.

Here is a link that might be useful: Bathroom photos

"...drill a small pilot hole where you want the nails to be. This will avoid splitting the trim."

Using a nail gun will also eliminate almost all splitting.

I use a Paslode 16 gauge angle finish nailer for trim work.

The 'nails' are t-head style and range from 1 inch to 2.5 inches.

The single stroke of the nail gun with thinner nails is less likely to split wood.

I can nail even 1 inch pieces of 3/4 inch oak quarter round without any pre-drilling.