rusty screws

My wife and I are repainting some bedrooms and we took out the screws holding up the curtain rods. the screws were held in with plastic anchors and were in the outside wall. The screws came out with the tips rusted. The screws have been in the wall 26 years, since the house was new. I have heard that houses can breath and can carry moisture from the inside out. Could this have rusted the screws or do I have a different problem?

I would suspect the moisture is getting in around the window frame. Either where the frame caulks to the siding/brick, or getting in through the frame itself, where the tracks meet the sill, screw holes, hardware holes, etc.

Once inside the wall, condensation would carry it up. Probably be worth looking into.

I doubt if you have a moisture problem if that is the only evidence. Likely the gypsum in the drywall had some chemical reaction to the plating on the screws.

Long screws?
If so the steel will conduct heat and the tip will be in the cold=condensation
I wouldn't SWEAT it

I have seen this a lot, do not know if issue.

Carpenter probably held the screws in his mouth as he needed them? LOL

Are you in a cold climate? Does this wall have eaves over it? If so it may be ice dams.

The two most common causes of excessive moisture in a wall are leaks from the roof or siding, or leaking plumbing in the wall. Exterior walls under gutters on houses with box eaves (no roof overhang---back wall of gutter flush with exterior wall of house) are notoriously subject to leaks. Failed caulking around windows is another common cause of water getting into walls, particularly on the side of the house that faces wind driven rain the most.

Theoretically, you should be able to inspect the inside of a wall without opening it up. Cameras on flexible shafts are used for all kinds of such jobs. A person who did that for a living would have to be experienced enough to recognize visible clues which might be quite subtle. I've opened up hundreds of exterior walls and frequently not been able to tell that wood framing members were rotted until I tried pushing a screwdriver into them, or that fiberglass insulation was wet until I touched it. In some cases, if there were visible clues, they were too faint for me.

If the tips of all the screws are rusted, I'd be more inclined to view it as not a problem---especially if there are windows in several walls. The screws at the ends of each set of curtain rods are going into different stud channels, so if you have multiple windows, and/or windows in walls facing different directions, that's a lot of stud channels to be having the same moisture problem. It's still possibility, but less so than if only the tips of screws from one location are rusted.

Opening up walls and doing a physical inspection is fairly straightforward for someone who has done it a lot, but there's a fair amount of work involved. Cutting and removing drywall, for instance, can be done cleanly, but not the first time you do it. Well, maybe you can get good enough advice on YouTube to do it right the first time. In any case, if you decide you want to open a stud channel to see if there's a problem, you might as well wait until you're ready to repaint the bedroom, or at least until a time of year when it's convenient to do so. If it's been 26 years already, a little longer shouldn't make too much difference.

Stan

you may have a moisture condensation problem in your wall. the warmer air inside carries a higher water vapor content. A wall should be designed with a low permeability material on the warm side and progressively increased permeability of each material as the vapor travels thru the wall so as not to be trapped.A moisture barrier paint on the inside usually helps

OK, I couldn't, for some reason, get in to the board the last two days, but here I am.
Answer some questions.
I live in Missouri about 45 miles west of St.Louis.
When we took the curtain rod down, only one side's screws tips were rusty. The window is centered in the wall, so the conditions are pretty much the same for both sides.
The installer (me) did not put the screws in his mouth.
I have been busy helping a friend move and haven't checked the calking around the window. 5 years ago when we repainted the house, I renewed the calking around all the window and doors.
The screws are about 1 inch long, in a plastic anchor and only about 1/8 inch at the tip is rusted. I am thinking that the 1/8 inch that rusted is the part that is sticking out of the anchor or the insulation.
John