I agree with @Raimondi's comment except for the "60%" part. If you set your humidifier that high in winter, or really even above 40%, you will get condensation on your windows, which is destructive. Even the best windows in the world cannot stand up to chronic condensation coming from humidity levels set too high in winter. The frames will eventually deteriorate and rot. You can go on the Windows Forum where Windows Pros hang out, and they will back me up on this, as the issue comes up often.

Ideally, get a whole-house humidifier for when the heat is on in winter, and set it to about 35%. Note that depending on your climate, indoor humidity in winter without a humidifier can be as low as 20-25% which is what the Sahara Desert's humidity level is.

Won't a piece of quarter-round fix that?

What about the super elastic type o painters caulk that moves with the seasons, anyone know any specific products? I have some painting to do and would like to know myself! Ive used polyurethane caulk on the exterior and its held up beautifully but really difficult to apply so didnt want to attempt indoors where messy application would be more noticeable. OP, I would be inclined to just leave it! The line between ceiling and cab doesnt look very wide in the pic, and it's straight so I dont kno that I would consider it a problem.

I'd caulk it with flexible caulk. Dap Dynaflex 230 is great and available in lots of colors so you may not even need to paint (don't use silicon caulk; it's not paintable). Use a drip free caulk gun which prevents the caulk from continuing to flow when you release the trigger; Home Depot had them for less than $10.

We have that issue constantly because our kitchen isn't heated and our house is on clay soil in a climate with wet and dry seasons. We have caulked it once or twice in the years since we installed the cabinets (and our cabinetmaker caulked it well at the beginning) but mostly I just ignore it. It's a downside to running cabinets all the way to the ceiling in a house like ours, and the many upsides far outweigh it. And yes, if you caulk it, it will eventually separate again (but as suggested, using flexible caulk will help stretch that timeframe out).

When we had our kitchen renovated a few years ago, we had our cabinetry extended to the ceiling with simple classic molding. Our experienced carperter did not use any caulking at the top, where the molding meets the ceiling. He said caulking usually seperates in time.

Hello, I would suggest You put up a nice Moulding as suggested. before, but secure the Moulding to the ceiling not the cabinets, let the trim float on the cabinets. There will probably be a difference in movement between the ceiling and the wall so securing the trim to the ceiling will prevent the gap from reoccurring again.

Good Lusk Woodbutcher

I'd rather maintain a more modern appearance with some caulk rather than load the cabinets with ponderous moulding.

@wdccruise, thank you. I agree!

Thank you everyone! We had our one year punch list walk through today and decided to go with the caulk. I appreciate your thoughtful replies.