Well, I haven't tried it, but I imagine it might be sufficient to evaporate the water as it condenses on the windows.

But... it feels to me like it's just as likely to make the problem worse, by increasing the potential humidity of the room (as warm air holds more moisture).

Maybe in a place like Chicago, where it doesn't get very cold, it might work? Up where I live, I cannot see this being a tenable solution at all.

This happens because the warm and humid air holds more moisture than cold air. When the air touches the window, it cools down and the excess moisture collects on the glass, eventually enough collects to drip down.

I'm guessing you don't have some sort of AC/central air which would help reduce the air humidity.

Better insulated windows would help, but likely isn't an option.

So you'll want to try to dehumidify your warmer air. Most likely with a dehumidifier.

But the fittings are sold specifically stating PEX compatibility. I personally use them for repairs.

Don't trim it, move it out a little bit. If you trim it, you might chip the finish or end up with an uneven edge that will bug you for years. But if you pull out the dishwasher to see how the side panel is attached to the countertop then you may be able to unscrew a couple of brackets, move the top just 1/8" and screw it back. There's a good chance this will be enough and you won't have to also move the bottom. But if you need to, then pull out the quarter rounds, try to gently tap the bottom to move that out as well; it might just move enough to give you the clearance you need.

Heat pump won't help here. During winter heat pump transfers heat into the desired space for warmth. This drives the air inside to be of conditions that cause a cold single pane window to condensate. Think of a cold can of beer on a hot day; it sweats. Same thing here.

Dehumidify or insulate windows using a secondary pane or other product are only solutions.

Exactly. OP can unscrew the fixture and will probably see hot black to fixture, white to white, and black coming back from the switch to the fixture. It's an easy fix. Hot black to switch-leg white, returning switch-leg black to brass screw on fixture, chrome screw on fixture to neutral.

Dehumidifier will work but only if you drop the humidity level far enough in the house which is miserable yo live in. But like you said that completely goes against the whole point of adding humidity in the house for comfort. Even high end windows can suffer from this when temps drop. Generally double hung windows get it worse than casement windows.

One thing that can help is to get air movement against the windows. If you have curtains keep them closed at night but open them for a while during the day and see if it helps clear it up. Otherwise a quick wipe with a towel is the quick solution.

I'd cut it. But if you're worried about it, build a support box the length of the tunnel by cutting 4 pieces from an appropriate size board, then use some wood glue and some brads to make a 4 sided box. Place it in the tunnel making sure it fits firmly by using a hammer to knock it in. All you need to do then is affix the cat flap.

ADDITIONAL: I just want to add that if your cat is anything like a cat I had a few years ago, she'll look at the door flap at first with suspicion, then with trepidation as she'd go over and hit it with her paw a few times like she was testing it. After testing it she'd walk away, sticking her tail, and head into the air ignoring the flap from then on. Coming home from work one night we did find her stretched partially through the flap yowling her head off like she was singing holding a catnip mouse, completely high. She only did it once. At least that we caught her at. So good luck with your door flap.

You use Gutter seal. you can buy it at home depot.

that is one way to do it. another is to make an I with short pieces so you can nail in to the cross piece from top and bottom then nail/screw the short pieces to the stringers.

the good news is that with easy access to the under side, even if your fix doesn’t work, you have access to try something else easily.

The colder it is outside, the lower the humidity needs to be inside to stay above the dew point and avoid condensation. Basic whole house humidifiers just have a % humidity setting which can cause problems when temperatures fall as you mentioned. There are nicer controllers that also measure outside air temperature and automatically reduce humidity when it gets colder outside. Talk to your HVAC professional about this.

The plastic wraps may help. Found in any home improvement store

Ya brock is right. Just make sure the upper cabinet is screwed to the wall good as it really holds a lot of the weight. Use butterfly anchors where you can't hit studs on the back bracket. But if you feel better putting a piece of blocking from the back side for sure is easy and won't hurt. If it was me and I could add blocking easily I would but hung many of these on single stud and anchors without issue

Your switch was wired "backwards". Easy mistake to make and to fix. Singe pole single throw switches work both ways, so there really is no backwards. If it were a different kind of switch you might be in trouble. This not a danger to you unless you have wild OCD.

I had this problem with our first house. I bought plastic film window kits. It uses double faced tape that you stick on the window frame and then stick the plastic film to. Not only did it keep the condensation at bay, it blocked out drafts.

Condensation on windows is caused from your house being too humid during the winter when your windows are cold.

Dual pane/insulated windows will be much less likely to have this problem than old single pane windows. Upgrading the windows will probably solve the issue.

If you are stuck with old, single pane windows, and replacing them is not an option, then the other option is to try and reduce the humidity in the house. You could run a dehumidifier, but a better option would be to evacuate the humidity via ventilation to the outdoors. Humidity typically comes from your bathrooms, stovetop ranges, and washer and dryer. Ideally, each of those rooms or appliances should be properly ventilated to the outside.

A plane or a sanding machine

All of this sounds wrong. What kind of insulation is that heavy?

I did something similar to what you’re describing- a pass through box. So I can run a small generator & leave the doors & windows shut.

What would a heat pump do?

A lot of garage doors are insulated with styrofoam panels which are just glued on to the door so they are very lightweight and can easily be replaced by homeowners.

Styrofoam panels are available at nearly any hardware store and the job would probably cost less than $500 - $800 and a weekend depending on the size of your doors(s.) You’d just need a few simple tools and adhesive and you could do it yourself. I’m sure there’s a YouTube video on how to do it.

Do you have any actual construction experience?

Sink a lag bolt into a stud and let it stick out a few inches. Stand on it. bounce on it. Really give it hell. Then mount the microwave with one stud per the instructions. It's more common than not and will be absolutely fine.

This doesn't soundproof as much as it reduces echos inside a room, giving the sense that things are quieter without actually preventing noises from entering or exiting the room very much. If you want to sound proof you need denser material. A new threshold and weather stripping on the door is inexpensive and would make a big difference. If you don't want to remove the door then screwing the thickest piece of sheet rock to both sides of the door would help as well.

It’s worth noting that some states have set code for air gaps I.e WA. I still removed mine and the inspector didn’t say anything. Go for it!