It's not necessarily that the mitered joints of the FJ molding will open up more than non-FJ molding. Mitered joints for FJ and non-FJ will act the same for same-species woods. It's that the actual finger joints themselves can swell a bit, causing some or all of the glue lines to telegraph through the paint. You can end up with little vertical lines every 12-18" or so along the run of molding. FJ molding has gotten better over the years. But the humidity swings in a bathroom could certainly challenge any FJ trim. Coping really isn't time consuming. I have to preface that I never use caulk on any molding. My mitered joints are tight, no caulk needed. When attacking an inside corner, coping is actually faster than mitering, especially if the joint is not a perfect 90-degrees. Coped corners will not open up with seasonal movement like a mitered joint will. So the sort of funny thing is that coping can be faster, and more durable. I will say some folk are intimidated by coping. MDF can be coped too, but the pointy end can be fragile. But it's ridiculously easy and coping can eliminate a lot of joint problems caused by wood movement and mitered corners. Mitered corners? I think mitered MDF can give a more stable inside corner joint than mitered softwood. Softwood (most any wood) has unequal rates of movement along it's length versus its width. When lumber shrinks more across its width than length, that's when mitered joints can open up, the "V" gap is very typical. MDF has a lesser rate of movement than wood like pine, plus it moves equally in both dimensions. So an MDF joint could open up, but it's less likely to do so, because it moves less to begin with, plus because its equal movement in both dimensions puts less stress on the joint than the unequal movement in a species wood. I hope that makes sense. If your guy uses MDF, then that's fine. You can get tight joints with MDF and with glue, they can be durable. An advantage of MDF is that it is a uniform material, there is no unequal expansion on one dimension when compared to another. So miters are not stresses as much with MDF as they might be with a true wood like pine. FWIW, when mitering inside corners for crown, I cut the piece of crown slightly long. Maybe 1/8" +/-, depending on the length of the stick. Then I bow the middle part out away from the wall to get the two ends in place. With the corners set, I then "snap" it in place by pushing the bowed middle against the wall. That compresses the mitered corner joints, making them less likely to open. The not understanding of "the backing part", it's fairly simple. I've already written a thousand words, so hopefully these photos will allow for brevity: A glued butt joint on a 1" by 4" piece of crown will have a glued surface of maybe a little over 1 square inch. And that glued surface will be end grain, which is a weak glue joint. Now add a glued backing block behind that same butt joint. If the block is 2-1/2" by 6", it adds another 15 square inches of glued area to the joint. Much stronger. Here's a backer block on the back side of a couple of pieces of crown simply butted together: What the side view would look like: And another:

super jealous of your old apartment!!! now, along the lines of lowering the opening in my family room, here is a photo of that opening taken from the foyer. this picture also shows what will be the cased opening in the hallway. the hallway cased openings should probably remain 9 ft even if the family room and dining room openings get lowered a foot, right? any thoughts on how i can do this so it doesn't look terrible? is it ok for hallway cased openings to be taller than door-less entrances to rooms? by the way, the other doorway you're seeing in the hallway is a closet and then, beyond that, is the opening to the butler's pantry.

Wow, I would be pleasantly surprised to see that, not disappointed. I think that shows an excellent builder who has the wherewithal to give that type of attention to a small room. I have crown in two of my bathrooms (master bath not yet) and the smallest being 5x8 and we deliberately added it years after it was built. I think after it's all done you will see how moulding adds to the finished look of any room.

Well, our kitchen cabinets are being made as we speak so I'm talking about what's on paper .... However, our house at present has no crown moulding, so the crown which will be installed throughout the house will also be installed in the kitchen. (I know, not helpful so far.) The kitchen is going to be a fairly bright white -- I mean, the kitchen cabinets and wainscoting. The trim in the rest of the house is almost a pale yellow -- it's a deep, deep cream (Benjamin Moore Calming Cream). We'll have all the kitchen crown and other trim (windowsill, baseboard, door casing) painted to match the fairly bright white. We'll have to have plinths where the kitchen meets the family room, though, as it will be in the Calming Cream and would just look plain goofy (I think) to have white meet yellow. Our colors are noticeably different. I'm having a hard time envisioning your two colors (the white with charcoal glaze and Navajo White) and if they'd fight or if there's a subtle enough difference so that it would be okay to have both in the same room. I like the idea of continuity, either whole-house continuity or room continuity. I think for a kitchen, which will have so much of the painted finish (cabinets, trim), I'd vote for the crown in your kitchen matching the color of your cabinetry (doing all in the white with charcoal glaze). Sorry I don't have anything to show you nor can I give you more help .... Good luck!