Damp insulation in attic

Reply

  #1  
Old 01-27-08, 05:45 PM
e40
e40 is offline
Member
Thread Starter
Join Date: Oct 2005
Posts: 12
Damp insulation in attic

Hello -

We came home today to find a leak on our ground level, creeping out of the casing above a doorway.

I went upstairs, and entered the attic and noticed a couple things. First, the north end of the attic (which is still very snow covered, and doesn't get much sun) was damp everywhere. On the insulation, on the trusses, and on the roof sheathing itself.

On the south section of the attic where it's nice and sunny, the roof sheathing was nice and dry, and the insulation wasn't damp.

The only thing that comes to mind is poor drainage on the north side of the house. The gutters were all full of ice, and there was considerable ice build up in the valleys leading to them. The gutter that services the section that's currently damp is not flowing either. There isn't a considerable ice dam, like you see on some houses, but the gutters definately don't hold water anymore.

This is a newer home - and we've had more snow than usual this year. Should keeping the north gutters flowing solve this problem?

TIA
 
Sponsored Links
  #2  
Old 01-27-08, 06:25 PM
Member
Join Date: Sep 2005
Location: ohio
Posts: 195
Keeping the gutters flowing will help..some. But if you actually have ice dams then its really only a band-aid, The way to solve ice dam problems is having both proper amounts of insulation/airsealing and ventilation in your attic space. The dampness you see is probably the result of moisture laden warm air coming from below and condensing in the cold attic. Can you describe the size of the attic and what kind of ventilation set up you have? How thick and what kind of insulation do you have? Do you see any gaps in the insulation and are all penetrations of the attic caulked or foam sealed? Are any soffit vents blocked if you have them?
 
  #3  
Old 01-27-08, 07:15 PM
e40
e40 is offline
Member
Thread Starter
Join Date: Oct 2005
Posts: 12
Hello -

I don't believe I have any heat penetration to the attic.

This attic space is about 30x30 and is over the upstairs bedrooms, bathrooms. There is a ridge vent along the entire length, and there is blown insulation. (Evenly blown, I cannot recall the depth). No other attic vents are present. If I slide the insulation over to see the drywall beneath, there's a poly vapor barrier, then the drywall. There are those foam inserts to allow venting to the soffit. The soffit vent isn't obstructed.

My IR temperature gun was reading about 25F evenly all around, with the outside pretty close to that. Inside the home is currently 70F.

This has been an interesting winter. We had record snowfall, and the first snowfall was really wet and heavy, then it RAINED on top of that, making a really hard shell of snow. (Half of my driveway is un-plowed to this day because of it.)
Anyhow, I believe all the gutters filled up and froze, and never thawed out.

Today, it got really warm, in the mid 30's, and the south side of the roof melted really quickly, where the north side didn't budge as much. Although it must have been melting, cause of the wet sheathing.

Anyhow, it still puzzles me how the damp sheathing was split exactly North/South. (North is wet, south is dry, the ridge vent runs east/west).

Looking at the wet (north) side:



Here's looking straight up, the dry side is the top half, the wet side is the lower half on the other side of the ridge vent.

 
  #4  
Old 01-28-08, 06:50 AM
badeyeben's Avatar
Member
Join Date: Dec 2006
Location: Southern ILLINOIS
Posts: 944
Does the vent from the bathroom go outside or into the attic? The vent fan from the bathroom must vent outside or it causes just what you are seeing. The sheathing, where the snow is still on it, is cold so it is therefore drawing moisture. If the vent is vented outside, then check the pipe to be sure it does not have holes in it. Tape any joint in the pipe. Check to see if there is any uncaulked or unfoamed openings around the bath vent or ceiling light boxes in bath and bedrooms. I say bedrooms too as you may be running a humidifier in the bedrooms.My guess is warm moist air is coming in from below causing the problem. Anywhere something penetrates the plastic vapor barrier is a place that needs to be caulked or foamed to stop leaking air.
 
  #5  
Old 01-28-08, 07:39 AM
e40
e40 is offline
Member
Thread Starter
Join Date: Oct 2005
Posts: 12
Heh, now I need to slap myself with a Clue-by-four.

For the past couple days, we've been running a warm air misting machine thingy in the baby's room because he has a cold. Sometimes it's like a sauna in there. The only penetrations through the barrier would be the outlet boxes for the light fixture, and the smoke detector. A small air leak from one of those is all it takes, even with the deep insulation? I could use my IR gun on those spots, too, to see if there's a drop in temperature around them. I'll check it out when I get home.

Thanks for the reponses so far.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes