weird home question

so every winter in the master bedroom water spots start appering in the corner on the ceiling, both walls are exterior walls, anyone have any idea whay this happens, i can get pics of it helps.

Check the insulation in the attic in those corners, could be condensation building up. Also, is this happening with snow on the roof, could be ice damns leaking into the corners

I'll bet a dollar that the insulation in those spots is insufficient (got wet, squirrel or mouse nest, bunched up away from that spot, etc.) compared to the other areas and the drywall is very cold so that when the warm coal heated air hits it the moisture condenses on the drywall. Do you also see "ghosting" of the ceiling joists or drywall nail heads shadowing through on the drywall?

didnt noticed if i have the "ghosting", ill go and check the insulation now. doesnt matter if theres snow or not on the roof

It is probably insulation (or lack thereof) and the warm moist air inside the house it getting up to the roof and condensing back down thru the ceiling. You also need good ventilation from the eves up to the roof rafters, make sure the channels are clear or put those Styrofoam panels to keep the insulation out of the eves.

Do you have a bathroom near that room? Is the exhaust fan working properly or been cleaned lately, if not, check that. it could be working, but not moving the moisture outside.

Yes, the snow could melt and then freeze in that area, cause some ice, then another melt and it could back up under the shingles and start dripping down.

I know now with new roofs, they have to put at least 3-6' of "Ice Shield" a sticky membrane under the shingles to prevent this. It seals up anything that could back up under the shingles on the roof.

the weird thing is its so dry in the house, the stove dries everything out, even with a pot of water on it. so there should be no insulation in the eves?

Do you have insulation in the exterior walls? Maybe it has settled created a cold spot on the walls for the warm air to condense.?

Is the floor in the attic insulated (basically ceiling of the second floor)?

Any snow or ice on the roof when this happens? Is it raining? could be just a bad spot in the roof.

"Normally" There should be some type of airflow from the overhangs (eves) into the attic and up to the either Ridge venting, Turbines, or gable vents of some sort. Not always true in some cases.

Check to make sure there is insulation covering the area in the attic where you see the moisture in the room.

Any water pipes, a/c units or anything in the Attic area where the moisture is below?

This sounds like a classic condensation issue. Inside the room, it's warm from the coal stove and there is humidity from your pot of water. The ceiling is cold on the attic side, (probably insulation out of place) and warm on the living space side. Just like a single pane window, water condenses there. You either don't have insulation there or alot of times I see where wind has blown in the soffit and moved all of the insulation from areas near the eave.

I agree with the others....for one reason or another that part of the wall/ceiling is staying cooler than it might. It drops below the dew point and voila, water.

A perfect roof needs no ice and water shield, but a perfect roof is a tricky thing. The idea of proper insulation and venting is two fold: Keep heat in the house, keep the roof cold. Any heat that escapes from the house should be vented away before it warms the roof. That's when the problems start, the roof get's heated, snow melts & runs down until it hits the cold roof near the edge, then it freezes. The ice will get thicker and thicker, eventually making a dam. Once the dam gets high enough the water leaks though the shingles. This is where ice & water shield does it's job. So, good insulation, soffits vented, roof ridge vented is the answer. They make stuff called "proper vent" that goes between the roof rafters. It's stiff styrofoam zig-zag stuff & it's job is to keep insulation from touching the roof and to maintain a 1 1/2" vent space so air can move from the soffit to the attic area. If you have a cathedral ceiling, the proper vent should run the entire distance from soffit to roof vent.

If the wet spots are sweet, I'd say bees.

Good point, we had the same problem, could hear weird sounds and a weird stain on the ceiling. almost like a mouse or bat scratching every now and then....I banged on the ceiling and all of sudden it started humming..then I accidentally poke my finger thru the ceiling tile while tapping and bunch of honey bees fell out!! Yikes!! Quickly killed a few and tried to figure out how to get the bee spray up in there without disturbing too much, first attempt was in the eyes (ouch) after it came raining down on me, then I put a tube on it and shoved it up thru a tiny hole....got it! Put some clear packing tape on the hole....

Outside, Found the little crack in the roof line/siding and sealed it up the next day....boy were they pissed!!

Freddy and his dog are absolutely correct about proper eave and roof ridge vent. The small amount of warm air that is permeating thru the ceiling insulation rises and pulls cold air from the eave, this starts a cycle with the warmer air rising out of the roof ridge vent/wall end vents. There is only a couple degrees difference in air temp but that is enuf for the air to rise.

I have eave vents with the "proper vent" and roof ridge vents for the past 20 years and no north side ice dams. My neighbors on the other hand, water in wall.ceiling, etc.

I've had that happen twice, both times it was the bathroom plumbing vent. Once it was water getting in around the rubber seal on the roof then following the PVC and dropping on a non bathroom ceiling. The other was last week, water running down the other bathroom vent (inside the pipe) and exiting through an unglued joint and dripping on the bedroom ceiling. A stucco ceiling friend said it was a dead rat so we were pleased with the vent problem