...and two reinstall 2 vents...$850...?????

Get someone else to look at it.

There is one large vent in the roof. The two bath vents are very close to each other and are attached together hanging just below the opening to the roof vent. It was this way for 20+ years.

Before I have them 'properly' re-installed, is there any way the mositure from here that does not travel 6" or so to the roof vent and out of the house, can work its way down the roof, thru the insulation and condense on my bathroom ceiling....AND ALSO ...travel across to the bedroom opposite the bathroom, again work its way thru the insulation and condense on that bedroom ceiling....again on that fatefull day ( it only happened twice) the temp outside was zero and we had the heat cranked up to 75 in the house...

I hate to have these moved if it won't prevent this from happening again under similar situations.

Warm, moist should be going through ductwork that is continuously connected to the outside. When the ductwork stops short, that warm, moist air runs into the cold of the attic area and the water immediately condenses out. it's not surprising you have a problem, but the fix should be easy...connect the ductwork to the vent and insulate the whole run.

I'll try to get a picture. I get what you are saying however I find it difficult to believe the mositure is flying to otherside of the attic, fighting its way thru a foot or more of blown fg insulation (or lowering its R value as I was told might be happening) , then getting thru the drywall and condensing on the ceiling.

It feels to me more likely that more insulation is needed in that area. I feel it was so cold up there that week last year and room below so warm that the condensation occured on the celing from the inside. In fact, if it was from the bath fans, why would I know have had this issue in every room?

I guess I need another insulator's opinion.

The preferred configuration for bath van ducting is to exit the bath ceiling and then go horizontally (fully supported and sealed) over to a side wall with a slight slope downward toward the outside. As the humid air cools and condenses, this allows moisture to drip down the inside of the pipe toward the exterior vent and not back toward the fan or ceiling. Running the vent straight up to the roof will work, but in cool weather the condensation in a long vent has to run somewhere, and it may be back into the fan housing or onto the ceiling.

One reason it may be so expensive to fix the venting is that to do it correctly includes putting one or more holes in your roof. If you have a two story house this is not a simple inside HVAC or insulation job, since someone must be both inside and on top of the roof cutting holes and installing the vent and flashing. $850 may still be too high, but its hard to say without knowing the full scope of the work.

Bruce

Do you have a clear understanding of how well all ductwork in that attic is sealed at all connections and seams, and how it is insulated? That ductwork is poorly installed and, as you've furnished more details it has become clear that there could be a variety of reasons for the moisture problems. There could even be an issue with something else in the attic. The cold exacerbates whatever is not right up there. I'd be up there myself looking for issues. And if it happens again this winter, that would be a good time to further inspect since you might actually see what is going on.

Yup, ductwork done right, and insulated. Otherwise spray foam all ceiling penetrations (light and fan boxes, bath fans, plumbing vents, electrical runs). I completely spray foamed over my bath fan that was in the attic. There are plenty of holes in the housing for air leaks. Anywhere air leaks into the attic will allow moisture up there to condensate and possibly show up. Also make sure your attic access is nice and tight. My access is caulked and when I need to go up there I just cut the caulk and put another light bead on when done.

Also I prefer a roof bath vent rather than a soffit vent. The air coming out of a soffit bath vent is warmer and will just rise into the roof through the soffit if the soffit has holes for attic venting, or it will condensate on your soffit if its solid and mess up the paint job or rot it.

ditto what kudzu said.

ill get you all some pics over the weekend. Spayfoam etc is beyond my abilities in there...there is a foot or more of blown fg insulation...I'll get pics though...

I asked if he saw a lack of insulation in the areas where I saw moisture...he did not say. I should have popped my head in to see exactly what he did up in there. For all I know he just zoomed in on the venting and snapped a picture.

Move the insulation and get spray foam cans. ^^

Vith, I completely agree with you about not wanting to vent through the soffit - but one can also vent horizontally through a gable.

Ahh true that, I actually like wall vents because you can use the vent that has a positive closure when not in use. A bit unsightly, but they work great. I always forget about the gable, my house has a hip roof.

And they should be wrapped in insulation.