I have a cathedral ceiling, 16 foot run, northern exposure, 4 years old. I am having moisture leakage problems. Under the plywood, in this order, it has styrofoam baffles, R30 faced insulation, 1 inch high R sheathing, 1/2 sheetrock. It has 3 cross beam coller ties. Soffet and roof vents run the lenghth of the ceiling. I live in CT.
This has been going on for over a year. When I opened a section of the ceiling up this week, everything was dry, but the paper lining, not the insulation itself, showed water stains across its width, so the water is running down from above the 1/3 high mark, between the high r sheathing and the insulation facing, and finding an outlet around the 3 cross beams.
Anyone have any ideas how I can fix this?
Thanks
Replies
I'm a total amateur but I've learned a lot hanging out here and I'll try to parrot it back to you. Sounds like you're missing a vapour barrier in there! Dunno what your "1 inch high-R sheathing" is exactly, but could it be an ineffective vapour barrier? That, combined with air infiltration through any penetrations in this layer which may permit infiltration of warm, moist air through your batts to the cold sheathing above, might be the source of your problem.
Seal any penetrations with spray foam, and paint your drywall ceiling with something less moisture permable. This "drying to the inside" business is all well and good, but if you don't stop moisture migration you're going to have moisture problems period. Better to keep the water out than to attempt to "dry" it out in areas where you're naturally trying to minimize the very thing that promotes drying- i.e. air movement!
sounds like you have a flat attic up high ?
if so , i'd cut my way in and look around..
you may have a poorly installed ridge vent with windblown snow melt
it sounds more like a leak than it does condensation.. although it's hard to say
if the insulation is wet in only one or two areas , i'd say leak..
if it's more universal, i'd lean towards condensation..
if it's the second ( condensation).. you may be able to apply a paint /vapor barrier
AND.. figure out where all the moisture is comming from ( shower, dryer vent, crawl space ?)
Got any pot lights?
yes, 2 high hats.
Is there snow on the roof? Both sides?
J.
A lot of ridge vents admit wind blown rain and snow. That could be the problem...but a bigger concern for me is the "faced insulation".
A cathedral ceiling needs a near-bulletproof vapor barrier, and faced insulation doesn't even come close. I'd much prefer to see a visqueen barrier, or some other type of mono-film. There are just too many leaks with faced insulation.
My next question would be when do you see the drips? Or the evidence of water?
Is it after precipitation? Likely a leak. With the limited info available, my first guess would be the ridge vent. Do you know what kind of ridge vent is installed?
Is it during the winter/spring cold weather? Then I'm more inclined to say condensation. Moist/humid air from the living space is making its way into the rafter bays, coming into contact wiht a portion of the roof structure that is below dew point, and the condensate runs down the ceiling.
As csnow asked, any can lights or other penetrations through the face of the vathedral ceiling? Bad. Same with ceiling fan boxes, etc.
Were the crossbeam penetrations through the face of the ceiling properly detailed, vapor barrier wise?
During recent snows, have you looked at the layer of snow on your roof? Notice any melt patterns? ie, does the snow first melt near the ridge, or over the rafters, or over can lights, or where the cross beams intersect, etc, etc?
There you're looking at thermal telegraphing via the framing or heat leaks via inadequate insulation.
Just some ideas.
Where abouts in CT are you?