Ice / Frost inside attic - How to remedy?

Reply

  #1  
Old 02-22-14, 02:49 PM
Member
Thread Starter
Join Date: Feb 2014
Location: Canada
Posts: 6
Received 0 Votes on 0 Posts
Ice / Frost inside attic - How to remedy?

Hello, I am going to go into a great amount of detail with pictures as to what my problem is. I know helping people without all the information can be difficult, and I want to resolve this before things get worse.

I live just outside of Thunder Bay Ontario, so it does get very cold here. This winter has been one of the coldest. We hit a low of -55C and have been hit with an excessive amount of snow this year. The reason I am explaining this is because this frost build up under the roof inside the attic was not an issue for the last 3 years we have lived here.

In 2012 I installed a bathroom ventilation fan for the bathroom as it did not have one. This did not seem to have any effect on the attic last year what-so-ever. What first caught my attention was when I was in the back yard (south side) this winter and noticed 3 brown syrup looking stains coming from underneath the vinyl siding by the oil furnace. They pretty much started from around the left and right sides of the bathroom window and went all the way down. Thinking it had something to do with the exhaust coming from the furnace to the outside I thought nothing more of it.

About a month later I went outside (east side) of my house and noticed a very large amount of these same brown syrup stains, plus it had also settled in to brown gobs in some areas where it looked like it had just stopped dripping. Now being very concerned I decided I had better check the attic after reading about Ice Damming - NOTE: I did not have any signs of ice damming from the outside such as icicles.

Once I went into the attic I was horrified to discover the amount of frost that had built up specifically on the north side of the attic. There was some frost on the south side (barely) but nothing compared to the north side. I noted while I was up there that the insulation (which was R50 at the time of installation) was not wet or damp; maybe a small spot here and there but nothing major.

I then went back down from the attic and turned the bathroom fan on to see if I could find any leaks coming from the insulated flexi hose that was being vented through the attic and out the roof. I did not find any leaks and all the connects were tight. I do however believe this is still the cause of my problems as it has been so cold this winter. Not finding any leaks in the connection or hose I then realized a huge mistake on my part. When I pulled back some insulation I noticed that there was the small gaps around the drywall where by ceiling ventilation fan was installed. So any moisture being pulled up from the fan also had the chance to escape from the sides. I will be purchasing some spray foam to completely seal this tomorrow morning.

At this point I wondered why I didn't have this issue last year as this spot was not sealed last year either. I should state that we have received about double the snow we did in the prior past few years so I normally only rake the roof of snow once every winter. As I climbed the roof I thought of another issue - The vents on the top my roof (attic ventilation on the south side) were completely blocked by snow. After clearing the snow off the roof I noticed that the snow above and around the vents was a sheet of ice which I had to break apart and lift off. All 4 vents had this same ice build up on top of them. underneath these sheets of ice there was no snow clogging the vents (they were pretty much in an igloo where no more moisture could escape.

Now on the south side of the house where the vents are it was pretty much regular snow that I removed. In the attic on the south side of the house there was very little frost on the underside of the roof. However on the north side of the roof, there was very little snow. What there was a lot of however was crystalized snow / ice. Inside the attic on the north side of the house was all the frost build up.

Going back to the above I should note that these brown leaks started happening as soon as it went from really cold to very warm the next day (-37C to -6C). I should also note I have not noticed any mold inside the attic or on the exterior / interior of the house. In fact nothing is noticeable inside the house until you go into the attic. On a final note I should also state that in the north side picture you can see a wood burning stove vent coming through the roof. This was professionally installed in 2011 and I inspected it while in the attic, everything was properly sealed so I have pretty much narrowed it down to my humidity leak coming from the bathroom ventilation unit.

My big question is what can I do to prevent all this frost from melting and leaking into the insulation as I do not want to lose any "R" value. Also, what can I / should I do to prevent mold growth from this once it gets really warm out. Both the East and west side vents on the sides of the attic were not clogged but did have frost on them from inside the attic.

I have attached all pictures.

Thank you for any help or advice that you can give and sorry for the long description.
 
Attached Images           
Sponsored Links
  #2  
Old 02-22-14, 04:19 PM
Member
Join Date: Oct 2013
Posts: 149
Received 0 Votes on 0 Posts
Can't tell, but do you have any soffit vents?

Has any air sealing within the attic ever been performed? (not just around the bathroom)
 
  #3  
Old 02-22-14, 04:24 PM
Member
Join Date: Oct 2008
Location: New England
Posts: 10,406
Received 23 Votes on 21 Posts
Far too long of a post for the simple solution. Sorry, but the answer is eliminating the source of moisture, usually air leaks, from entering the attic. Sometimes it is a bath or kitchen vent open in the attic. Very high humidity levels in the house can make conditions worse.

This topic has been discussed many times so a little searching may be beneficial. If there is something different, make it short.

Bud
 
  #4  
Old 02-22-14, 05:47 PM
Member
Thread Starter
Join Date: Feb 2014
Location: Canada
Posts: 6
Received 0 Votes on 0 Posts
To my knowledge, no there has not been any air sealing aside from the bathroom. Yes, I do have soffit vents.
 
  #5  
Old 02-22-14, 05:52 PM
Member
Thread Starter
Join Date: Feb 2014
Location: Canada
Posts: 6
Received 0 Votes on 0 Posts
I know what the solution is, and that is as you stated to fix the source of moisture - which I am doing. I have searched this and that is how I came to the source of my troubles in the attic. My concern was what to do with the moisture / ice that is already up there after the fact.

Thank you for your quick reply and sorry for the abundance of detail.
 
  #6  
Old 02-22-14, 09:29 PM
Member
Join Date: Oct 2008
Location: New England
Posts: 10,406
Received 23 Votes on 21 Posts
If the ventilation is working and the source of moisture has been eliminated, the current frost and moisture will evaporate, hopefully before it melts and drips. Frost and ice can go straight from a solid state to a vapor and cold outside air is frequently very dry.

Bud
 
  #7  
Old 02-23-14, 07:51 AM
Member
Join Date: Oct 2013
Posts: 149
Received 0 Votes on 0 Posts
darrylmiller, have you ever had an energy audit to determine how much air leakage the envelope may suffer from? Bathroom & kitchens can be a big source of moisture, but the rest of the house shouldn't be neglected from proper air sealing. Cellulose insulation is air permeable & vapor permeable; it won't block moist air from moving through it.
You seem to have a good amount of insulation, and if your attic is ventilated sufficiently, reducing the amount of air exfiltration from the living space into the attic is the last piece of the equation. Do you measure the relative humidity within the house to make sure they are in-line based on the season?

The only thing your initial post lacks is a "tl;dr" summary...I know how you feel with wanting to include relevant info, but realize that on the net, and especially an online forum, too much info could be detrimental in getting responses. FWIW, I read the whole thing Good luck.
 
  #8  
Old 02-24-14, 06:45 PM
Member
Join Date: Jan 2014
Location: usa
Posts: 466
Received 1 Vote on 1 Post
darrylmiller, First of all, about 10 years ago I purchased a piece of machinery from ThunderBay and when I called the seller he went into great detail to explain just how bad winter can be there....sorry for you!!!

After reading your query and looking at the pictures, I must admit, that is some of the worst frost accumulation I have seen.

I wish there was an easy way to deal with the question of minimizing potential wetting and damage to the insulation when the frost starts melting. As Bud stated you may have sublimation of the frost directly to a gaseous state but I really don't think ALL of it will occur that way. It will depend on how quickly a thaw takes place. Probably solar gain will have as large an impact on the melt as heat loss from the house.

I have a few comments regarding your observations. I get the impression that you are identifying the perimeter of the bath fan as a point of major air leakage and perhaps a dominant factor regarding your frost issue. If you do as others have suggested and research this topic a little on these forums you will find that air leakage paths in any dwelling are quite numerous and that water vapor will migrate throughout the structure despite being generated perhaps in only a few areas. As it migrates and "equalizes, it can be easily transported by air movement through literally any little crack in the framing to enter the attic space and accumulate in some form on the back of the sheathing.

To adequately seal air leakage paths is a tedious undertaking and when there is existing insulation it can be almost impractical to consider because of the task of moving all of that material around. Since your material appears to be light density fiberglass it cannot be disturbed without causing a loss in loft and when you change the loft you will change the R-value. Additionally, blown-in insulation typically has no separate vapor retarder other than the paint on the drywall so you are also getting the added effects of vapor transmission through the ceiling.

My other observation deals with your wood burner and your foundation. Do you happen to store wood inside the house? The moisture associated with drying wood can be considerable. How hot do you get it in the house? The warmth of the house is an attraction to moisture and unless your foundation has been dealt with to minimize vapor transmission...the warmer the house is, the greater the attraction to the moisture in the soil outside of your foundation and under your basement floor. This vapor will migrate and eventually make it to the attic to contribute to the situation you have.

I would also check the amount of ventilation you have and how it is divided. Regardless of the typical references to how much ventilation you should have, I would max out every possible vent opening you could provide. I would also get a device to measure relative humidity and perhaps check your local building office to see what might be a suitable measurement for the super cold conditions you have.
 
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
 
Ask a Question
Question Title:
Description:
Your question will be posted in: