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#7190423 - 12/16/12 Ice in attic
kk alaska Offline
Campfire Guide

Registered: 02/19/01
Posts: 3664
Loc: Eagle River Alaska
Had a energy audit and found ice in attic where I did not have soffit vents. Spent a miserable day putting in soffit vents and
insulation baffles in the attic. In one day most of the ice was gone.

Have soffit vents and gable vents with ridge vent. Have
heard where having both soffit and gable vents creates short ciruiting. So closed off gable vents. What are others doing
in AK to prevent roof issues?
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kk alaska

Alaska 7 months of winter then 5 months of tourists

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#7190503 - 12/16/12 Re: Ice in attic [Re: kk alaska]
Unalakleet_Yooper Offline
Member

Registered: 12/20/11
Posts: 148
Loc: Alaska
The house I am in did not have any venting last year and there were moisture problems. Gable vents were put in this summer and so far things are good. The reason given out here for no venting was the constant winds. I do believe a house has to breath somehow or problems will devolop.

The house I have back in northen Michigan has both soffit, gable, and ridge venting and I had no moisture problems

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#7190757 - 12/16/12 Re: Ice in attic [Re: Unalakleet_Yooper]
bobmn Offline
Campfire Regular

Registered: 01/25/08
Posts: 337
Another source of ice in the attic is caused by attic bypasses. This is where hot air is allowed to escape the conditioned air envelope of your heated space. The large amount of air cannot be dipersed by the attic venting. Examples of attic bypasses include gaps in the vapor barrier around electricle boxes for ceiling fixtures, gaps around plumbing vents and soffits over cabinets or showers. I had a huge bypass over the soffit in a bathroom shower. The dumbazzes that sheetrocked did not put any rock over the top of the soffit. Then the dumbazzes that insulated merely stretched vapor barrier over the top of the soffit and blew in insulation. Staples and plastic did not support the weight of the insulation. I had an impressive pillar of ice that stretched from bathroom ceiling to the roof. Also, make sure your exhaust fans are vented through the roof and the piping is air tight.


Edited by bobmn (12/16/12)
Edit Reason: spelling

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#7190807 - 12/16/12 Re: Ice in attic [Re: bobmn]
Take_a_knee Offline
Campfire 'Bwana

Registered: 09/10/09
Posts: 13799
Originally Posted By: bobmn
Another source of ice in the attic is caused by attic bypasses. This is where hot air is allowed to escape the conditioned air envelope of your heated space. The large amount of air cannot be dipersed by the attic venting. Examples of attic bypasses include gaps in the vapor barrier around electricle boxes for ceiling fixtures, gaps around plumbing vents and soffits over cabinets or showers. I had a huge bypass over the soffit in a bathroom shower. The dumbazzes that sheetrocked did not put any rock over the top of the soffit. Then the dumbazzes that insulated merely stretched vapor barrier over the top of the soffit and blew in insulation. Staples and plastic did not support the weight of the insulation. I had an impressive pillar of ice that stretched from bathroom ceiling to the roof. Also, make sure your exhaust fans are vented through the roof and the piping is air tight.


Yes, this is the most current building science, in my opinion. I'd reccommend stapling 6mil plastic sheeting to all ceilings of new construction, then nailing 1x4's over the sheeting to have something to screw the drywall to. Nail the ceiling boxes to horizontal 2x4 blocking and seal the hole for the wire with expanding foam. This helps minimize the "stack effect" in a home.

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#7196390 - 12/18/12 Re: Ice in attic [Re: Take_a_knee]
colorado Offline
Campfire Ranger

Registered: 10/27/07
Posts: 1841
Loc: Colorado Springs, Colorado
Down here in Colorado we have this dehumidifier called the sun ...

smile


Edited by colorado (12/18/12)
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#7196967 - 12/18/12 Re: Ice in attic [Re: colorado]
ChipM Offline
Campfire Ranger

Registered: 12/10/04
Posts: 2292
Loc: Southern New England
Another cause of improper ventilation is covering the soffit vents with insullation. Many believe the more the better but you need the attic to "breath". Between the siffit, ridge and gable vent you should have more then enough ventilation in the attic.

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#7197502 - 12/18/12 Re: Ice in attic [Re: kk alaska]
1minute Offline
Campfire Kahuna

Registered: 01/28/01
Posts: 16707
Loc: Burns/Hines, Oregon, USA
A local motel here was built with the swimming pool space vented solely into the attic space. Can we say collapsed roof and ceiling the first winter.


Edited by 1minute (12/18/12)
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1Minute

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#7197512 - 12/18/12 Re: Ice in attic [Re: 1minute]
UncleJake Offline
Campfire Regular

Registered: 12/18/09
Posts: 918
Loc: Los Anchorage, AK
A lot of sub-par building goes on here in Alaska. I know, you are all surprised....

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#7197514 - 12/18/12 Re: Ice in attic [Re: kk alaska]
Take_a_knee Offline
Campfire 'Bwana

Registered: 09/10/09
Posts: 13799
Probably the best way to build for a cold climate is to eliminate the attic entirely and have a vented cold roof. IE, this can be done with 4-6in of polyiso or DOW board on top of a T&G board ceiling. Then nail sleepers with pole barn nails to the ceiling beams/purlins. This space only is vented from the soffit to the attic. Classic Post & Beam in NY used this method and it had held up well

A slightly more expensive, but less labor intensive method to achieve this would be to simply use stress-skin panels and install the sleepers on top of them and deck and shingle/roof.

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#7197577 - 12/18/12 Re: Ice in attic [Re: Take_a_knee]
UncleJake Offline
Campfire Regular

Registered: 12/18/09
Posts: 918
Loc: Los Anchorage, AK
Hot roofs and heat trace are all the rage here.... crazy


Edited by UncleJake (12/18/12)
Edit Reason: "and heat trace"

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#7198156 - 12/18/12 Re: Ice in attic [Re: UncleJake]
MuskegMan Online   content
Campfire Guide

Registered: 09/30/04
Posts: 3087
Loc: S.E. Alaska

You want your attic space cold and well ventilated in the winter. Ice shield and heat trace on the eaves is a good idea to prevent ice damming. Frost is caused by the heat going thru the upper ceiling and going thru the dew point in the attic space. Good insulation and ventilation keep the top of the ceiling surface at, or below, freezing.

Another issue that I'm having a hard time with (and seems to be the rage with energy auditors) is a sealed crawl space under the house. No foundation vents and then a air "conditioning" system. And I don't mean cooling, but a humidity control and/or air exchanger. Anyone run one of these and have an opinion?

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#7198357 - 12/18/12 Re: Ice in attic [Re: UncleJake]
Take_a_knee Offline
Campfire 'Bwana

Registered: 09/10/09
Posts: 13799
Originally Posted By: UncleJake
A lot of sub-par building goes on here in Alaska. I know, you are all surprised....


When I lived in AK as a young man I barely knew how to build a doghouse, after moving the the 48 and learning to build quality homes, and seeing pictures of stuff that gets built up there, I whole-heartedly agree.

An engineer buddy of mine told me about a house some knucklehead built north of Fairbanks. It was slab-on-grade, like they do in Florida. Everyone told him he was an idiot but he scoffed. The house literally broke in half. The students from U of A would come out to see the carnage.

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#7198512 - 12/18/12 Re: Ice in attic [Re: Take_a_knee]
AkMtnHntr Offline
Campfire Kahuna

Registered: 08/15/06
Posts: 17497
Loc: Alaska
Our house was built back in 1978 and they put in a big vent pipe with the rotating cap to vent the attic. 2 years ago we had our roof reshingled and we had them install proper roof ridge vents and got rid of that stupid pipe. Now the attic seems to breathes better.

I do have one question though, I just remodeled our master bath a few months ago and put in a nice quiet Panasonic vent which vents out of the side of the house, above the attic. The vent cover keeps freezing open whenever we use it and I have to close it manually. Is there something we can do to keep this from happening?
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#7198640 - 12/18/12 Re: Ice in attic [Re: UncleJake]
atvalaska Offline
Campfire Outfitter

Registered: 01/13/10
Posts: 7878
Loc: 907novacancy
Have soffit vents and (****gable vents****) with ridge vent. **** cant have both- the gable has to go ...a bit late with that info i am.
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#7198703 - 12/18/12 Re: Ice in attic [Re: Take_a_knee]
atvalaska Offline
Campfire Outfitter

Registered: 01/13/10
Posts: 7878
Loc: 907novacancy
They built crap everywhere...but alaska and canada are lite years ahead in proper building know now...the trouble is some folks don't have to follow them - and don't.....
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Outdoor Culinary Engineer

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#7199170 - 12/18/12 Re: Ice in attic [Re: AkMtnHntr]
Sitka deer Offline
Campfire Oracle

Registered: 02/02/01
Posts: 26320
Loc: Anchorage, AK USA
Originally Posted By: AkMtnHntr
Our house was built back in 1978 and they put in a big vent pipe with the rotating cap to vent the attic. 2 years ago we had our roof reshingled and we had them install proper roof ridge vents and got rid of that stupid pipe. Now the attic seems to breathes better.

I do have one question though, I just remodeled our master bath a few months ago and put in a nice quiet Panasonic vent which vents out of the side of the house, above the attic. The vent cover keeps freezing open whenever we use it and I have to close it manually. Is there something we can do to keep this from happening?


There are a lot of options for dampers on vents... I prefer the floating balls.

Insulating the pipe right to the vent will keep the vented air warmer and slow down the frosting at the vent.

If you have a louver style a counterweight (small machine screw should be close to right) can be run through a slat and adjusted to weigh just enough to close the damper when the fan goes off.
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#7199256 - 12/18/12 Re: Ice in attic [Re: MuskegMan]
Pointbock Offline
Campfire Regular

Registered: 11/04/09
Posts: 396
Loc: Chugiak, AK
Originally Posted By: MuskegMan

Another issue that I'm having a hard time with (and seems to be the rage with energy auditors) is a sealed crawl space under the house. No foundation vents and then a air "conditioning" system. And I don't mean cooling, but a humidity control and/or air exchanger. Anyone run one of these and have an opinion?



We haven't done it yet but are thinking about it. We currently have a crawlspace w/ batt insulation in the rim and poly over the dirt floor. We're considering spray foam in the rim and "industrial" batts on the walls with the poly tucked under the bottom (and probably taped at the seams/overlaps.) Basically you're continuing your conditioned space down about 4'. We do have a couple of finned sections of hotwater baseboard in the crawlspace already. We haven't had moisture issues here in Chugiak with the current set-up but we might need some sort of a vent/exchanger if we change.
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#7199496 - 12/18/12 Re: Ice in attic [Re: Sitka deer]
AkMtnHntr Offline
Campfire Kahuna

Registered: 08/15/06
Posts: 17497
Loc: Alaska
Originally Posted By: Sitka deer
Originally Posted By: AkMtnHntr
Our house was built back in 1978 and they put in a big vent pipe with the rotating cap to vent the attic. 2 years ago we had our roof reshingled and we had them install proper roof ridge vents and got rid of that stupid pipe. Now the attic seems to breathes better.

I do have one question though, I just remodeled our master bath a few months ago and put in a nice quiet Panasonic vent which vents out of the side of the house, above the attic. The vent cover keeps freezing open whenever we use it and I have to close it manually. Is there something we can do to keep this from happening?


There are a lot of options for dampers on vents... I prefer the floating balls.

Insulating the pipe right to the vent will keep the vented air warmer and slow down the frosting at the vent.

If you have a louver style a counterweight (small machine screw should be close to right) can be run through a slat and adjusted to weigh just enough to close the damper when the fan goes off.


We have one that has a single louver in it, but never heard of the vents with the floating balls (there's a joke in there somewhere) but that sounds like the ticket.

Going to make changes this coming spring which I think will illeviate this problem too.
_________________________
That's ok, I'll ass shoot a dink.

Steelhead


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#7199527 - 12/18/12 Re: Ice in attic [Re: AkMtnHntr]
Dan_H Offline
Campfire Regular

Registered: 08/11/11
Posts: 610
Loc: Ak
There is a book about building practices in the arctic - I believe it is called "Northern Exposure". Spenard builders used to have them up by the registers. Great insight into venting, vapor barriers, cold vs hot roof designs, etc.

Not sure who I loaned my copy out to last, but haven't seen it for a few years.

It was well worth the $40 or so it cost!!!

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#7199950 - 12/18/12 Re: Ice in attic [Re: kk alaska]
kk alaska Offline
Campfire Guide

Registered: 02/19/01
Posts: 3664
Loc: Eagle River Alaska
Found biggest air leak in garage where forced air furnace exhaust vents outside. Tough to seal as it goes out at an angle and not create a fire hazard. Local fireplace store had a fireproof insulation.

Using a fabric cover over 4" foam block to seal heat loss through skylight no light in winter any way. Stupid skylights those that leak and those that have not leaked yet are the 2 common types here in AK! Have a drop roof between 2 roof lines
with a skylight. Heat loss in winter melts snow that drips on
deck, house entrance, a real pain in the winter. Insulating skylight keeps snow on roof and ice off stairs.

Lots of heat loss on outside wall plugs and switches which are easy to deal with and find in cold temps. Now trying to tighten heat loss on any ceiling penetrations, light fixtures.


Edited by kk alaska (12/18/12)
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kk alaska

Alaska 7 months of winter then 5 months of tourists

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#7199971 - 12/18/12 Re: Ice in attic [Re: kk alaska]
Take_a_knee Offline
Campfire 'Bwana

Registered: 09/10/09
Posts: 13799
Originally Posted By: kk alaska


Using a fabric cover over 4" foam block to seal heat loss through skylight no light in winter any way. Stupid skylights those that leak and those that have not leaked yet are the 2 common types here in AK!


I've installed over 30 Velux skylights, a few in upstate NY and the rest in the SE. I've had exactly one leak, and only in 50+mph winds.

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#7200763 - 12/19/12 Re: Ice in attic [Re: Take_a_knee]
UncleJake Offline
Campfire Regular

Registered: 12/18/09
Posts: 918
Loc: Los Anchorage, AK
The problem with skylights leaking in AK is that people up here love to have flat/low pitch roofs with poor insulating qualities. The snow sits on it, melts, and the weight of the ice/snow pushes the water through any crack and crevice, no matter how well sealed.

I live in Anchorage, and I see new houses going up that have no wind barrier, no vapor barrier, and 1/2" gaps in the T111 siding that are filled in with caulk. All this for $325k. You start throwing in other things like no drip edge on the roof, 2x4 walls, and inadequate ventilation, and then people act all surprised when their house starts falling apart in 10 years. "Oh, that's just the way it is up here, because our weather is so extreme!" has been told to me DOZENS of times.

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#7200768 - 12/19/12 Re: Ice in attic [Re: UncleJake]
UncleJake Offline
Campfire Regular

Registered: 12/18/09
Posts: 918
Loc: Los Anchorage, AK
Oh, and you gotta love the 6" soffits!

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#7200895 - 12/19/12 Re: Ice in attic [Re: atvalaska]
pak Offline
Campfire Ranger

Registered: 01/27/01
Posts: 1520
Loc: alaska
ATV, I'm not sure I agree with your soffet/gable or soffet/ridge. You might have to explain this to me. In my house I have gable, soffet, ridge vents and fans. Since we use and want the heat only while it is contained within the house, after it leaves the insulation I want it out of the attic ASAP. The reason I have all 3 vent types is snow can cover the ridge vents compromising the convective air flow. This is where the gable vents are a back up. The type of insulation can also be a factor. Blown in type can be moved around within the attic durning high winds. It is not uncommon to have a big pile in the center of the attic and bare areas around the edges.

I'm not real fond of the tyvex type house wrap, but prefer tarpaper. This is another topic.
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