NEED HELP. The north side of the house roof is wet inside.

[Part_Timer]

OK I know that this is going to sound dumb and I'm sure someone here is going to state the obvious but I'm freeking out.

We're working on the upstairs and we noticed some mold on the OSB on the north side of the roof this summer.  Well I watched all summer long and the roof was not leaking anywhere.  I was not sure what was going on.  Well now I know.

We went up there today and the whole inside on the north roof face is soaking wet 25' x 50'.  The South side is dry.  I went out side and there is a bit of snow on the north side but I can see the shingles through it.  There is no snow on the South side.  The pitch is 12/12 so there should be no water laying on it.

Is it as simple as the humidity up there is high enough and the North face is cold enough to make it condence?  The North side of the roof never sees any sunshine in the winter. Perhaps maybe not enough ventilation in general?

I'm open to suggestions.

[Coon]

I would say that you have a major air leak that the heat is escaping from thus condensing when the hot and cold air mix.  How much venting is there in the roof system?  I have seen this in the past with a couple of different houses that didn't have sufficient venting to take the heat away. 

[Furby]

What are your ceiling materials?
How much insulation is up there?
If there is no type of vapor barrier, then you for sure have a transfer problem.
There will be some condesation even with proper air flow from the eves to the peak,but better air flow should reduce it a little.
Unless we are talking about a leaking exahust fan from a bathroom or something.

[beenthere]

As Coon mentioned, sounds like a venting problem (meaning lack of enough air moving from the eaves up over the insulation and out the peak of the roof. Insulation can also be contributing to the problem, in that it isn't out over the top plate and between the rafters. Nowadays, thin foam vents are  used to keep the insulation from closing off the gap between the rafters, roof sheathing, and the top plate.

Some ice daming along that roof edge under the snow may also be causing some water inflitration, but sounds like you know there isn't an ice dam there.

How much venting do you have from the eaves up to the ridge? And, as Furby mentioned, the vapor barrier that limits the moisture from reaching this cold space.

[farmerdoug]

Sounds like condensation problem since the whole north roof is wet.  How do you have the attic ventilated?  At the rate you are going you will be do a roof job in a few years.  Most condensation problems are either caused by not enough ventilation or someone deciding that the trapped heat will help insulate the house so ventilation. :

Farmerdoug

[Don P]

Along with the above, I'm going to go with a vapor barrier problem. Crawl around and look for dirty insulation. If there is a mass air leak, say around a pipe or can light, the fiberglass will have acted as a filter, trapping dirt as the air rushes through it. Seal it if found. Above a moisture producing room is the most likely. And make sure any vents, bath fans, plumbing vents, exhaust outside not in the soffit.

[Captain]

If the inside of your sheathing is warmer than the outside roof, you are going to get condensation.

Is this area in the attic or your new living space?? How is the area insulated and ventilated??  Any ventilation fans such as bathroom or kitchen fans dumping in this space??

Captain

[Faron]

What kind of attic ventilation do you have?  Also, is there a bathroom vent terminating in the attic in that area?  I really think it must be condensation from somewhere.  My guess is you don't have vented soffits and a ridge vent.  Probably vents in the gables?  

Well, looks like these guys have my points covered, so I'll just post mine for emphasis. ;D

[Furby]

Don's posted reminded me of something.
If you have soffit vents and through the wall exhust fo something like a waterheater, furnace, fireplace and such, if it's too close to the soffit it can feed through it into the attic space.

Another REALLY bad air leak, is the actual attic access door.
I always make sure to seal them as good as possible.

[Part_Timer]

You guys are great.  I'm gona be able to sleep tonight because now i know there is nothing to do about it but work harder and faster.

Y'all hit it right on the nose.  We're still working on the upstairs.  The stairwell opening is 4' wide and about 10' long.  I have it covered with 2" foam insulation but it is not sealed off super well.  We're up there a couple of times a week working so there is only so air tite I can make it and still be able to get up there.  the ceiling is not in yet so there is no insulation up there between what is going to be the second floor and the roof sheathing. 

If I increase my ventilation would that help or just make the temp differance worse?  I could open one of the dormer windows a bit to help move some air.  I have a couple of dehumidifiers I could put up there for the time being if that would help as well.  We have gable vents and a couple of roof vents  WHat I realy need is a roof cap vent system.  Before we seal the ceiling completly I'm going to install a fan in one of the gables so I can make a good draw up there.  Maybe I better make that next on my list of things to do.   : : : : : :

There is no way to finish in the near future so any ideas on what may help would be greatly appreciated.  I should have know what it was but seeing the whole roof dripping and dropping small pieces of ice made me freak out. : : :

Thanks guys I knew I could count on ya.

[Don P]

We moved into our place with plastic on the window holes and no insulation. It took about 2 barrels full per night, the heat was going right thru the roof ply. We woke up one snowy morning and my wife said "look at the pretty icicles hanging out of the soffit vents  :"

Soffit and ridge vent is considered to be about the best usually. Gable vents work fine most places. Don't mix the 2 styles or the air "short circuits" and doesn't flush the space evenly.
DH won't do anything this time of year. You can try to live dryer downstairs, vent when you're doing something that really produces moisture. Exhausting up there will help if you're not pulling more interior air upstairs.

[Captain]

Since insulation is in the future, I beleive I would step up the plan.

First Ventilate with soffit and ridge vents.

Second, insulate leaving an air path above the insulation if you are doing your rafter bays.  Be sure not to block your soffits off with insulation.

Third, a good vapor barrier on the inside of the insulaton.

Captain

[farmerdoug]

PT,  Opening a couple of windows would help vent the place better.  Maybe you should get that gable vent fan sooner too.

Farmerdoug

[Furby]

There is this plasic with zippers in it used to cover doorways while doing hazardous waste removal.
Not sure where to get it, but might help you seal the air flow through your door and still allow use.
It may just be a stick on zipper and you slit the plastic after it's on, not sure.
I have plastic across my stairway to try and slow my heat loss in the house.
It may not solve your problem, but it should reduce it and I know it'll keep a bit more heat in the house.
You can use double sided tape or just staple it up. I also use some wood strapping tstaple through.

[mike_van]

I saw a house once that had the dryer vent just blowing into the attic - What a mess - Ice hanging like stalactites.