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Old 01-07-2009, 12:35 PM   #16
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


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Originally Posted by AllanJ View Post
Louver -- The semi-attractive grillwork that covers a fan opening or vent opening. For whole house attic fans it usually has movable parts to close off the opening but usually not good enough to prevent warm air from going up in winter.

Often the attic floor insulation, especially blown insulation, fills the eave soffit area and may even block existing soffit vents. Cutting new soffit vents therefore becomes a project. You need to clear away insulation and in most cases install (usually) styrofoam sheet baffles in the rafters to let air in and resist clogging as the insulation resettles.

These things?

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Old 01-07-2009, 12:42 PM   #17
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


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Originally Posted by Andrew Whitehead View Post
if you are getting that much condensation in your attic, did you make sure that you had a proper vapour barrier down before you had the insulation blown in? If not, the insulation maybe slowing the heat loss, but he moisture is still going through the same as before, if not faster since the inside of your house is warmer.

The plastic you put on your attic entries is pretty much useless, you need 6mm for a proper vapour barrier. I would also put a strip of rubber down where board lies. Since that piece isn't insulated, you might also think about buying some regular insulation so you can have a piece sitting on top of the board to insulate it.

As others have said, make sure your bathroom vent, as well as the vent over your stove both blow right outside, and not just into the attic.

An option for the stove fan is to replace it, and put in a new one that has a carbon filter and have it blow into the house so you don't have to do even more roof work, and it is one less area for warm air inside the house to leak out.
Should there be a vapour barrier placed on the floorspace of the entire attic? I know there is some underneath those whole house fan vents because when I removed it to put some pillow stuffing stuff in there, I can feel the plastic, but I do not know if it covers the entire attic space...

Example:
layer 1 : Attic floor.
layer 2: vapour barrier
layer 3: Pink insulation
layer 4: Blown insulation

If not, how on earth would I go about putting some now?


There is a piece of vapour barrier and some regular insulation sitting on top of the board. I have also stuffed a towel underneath where the board sits on the frame, then sealed it with stickey strips and plastic.

When he came to blow in the insulation, he attached the hose that goes from the bathroom fan directly to the gable end, though I do not think that hose is insulated. Would I need to buy another hose? or simply wrap a type of hose insulation around it?

Last edited by earthad1; 01-07-2009 at 12:44 PM.
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Old 01-07-2009, 12:51 PM   #18
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Drop by HD or Lowes . In the gutter/ soffit vent isle you will find the spec sheets on soffit to rooftop ratios for venting. Also try a few web sites for soffit ventilation info. I believe your square footage and pitch are part of the formula. No qusetion the soffits need to breath up through baffles now to vent the damp air trapped up there. As mentuioned check what`s venting into the attic from the bath fans, etc or you`ll be in nasty shape by spring. Don`t wait. If necessary reach out your bedroom windows to cut into the soffits, but investigate the baffles as well. One every other space is the norm in most new construction I have seen, at least one every 3rd.
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Old 01-07-2009, 01:04 PM   #19
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


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Originally Posted by Chemist1961 View Post
Drop by HD or Lowes . In the gutter/ soffit vent isle you will find the spec sheets on soffit to rooftop ratios for venting. Also try a few web sites for soffit ventilation info. I believe your square footage and pitch are part of the formula. No qusetion the soffits need to breath up through baffles now to vent the damp air trapped up there. As mentuioned check what`s venting into the attic from the bath fans, etc or you`ll be in nasty shape by spring. Don`t wait. If necessary reach out your bedroom windows to cut into the soffits, but investigate the baffles as well. One every other space is the norm in most new construction I have seen, at least one every 3rd.
Thanks...

So, based on all the responses and the online reading I have done. This is what it seems I need to do.

1. Ensure any leaks or warm air that may be making its way up from the living space to the attic needs to be sealed off.

2. Ensure that air is able to enter the soffit vents from the outside in order to have proper ventilation.



3.Install a ridge vent on both roof tops in order because this is needed alongside soffit vents for this ventilation system to work.



4.Block off both gable ends as these do not work with soffit vents, and are, therefore, creating a short circuit effect on my soffit/ridge vent combo.




So I guess my question would be: why do I have gable ends and soffit vents to begin with if they are proven not to work properly togther... Seems a real genius built this house. I've only owned it since early 2006. It will be 3 years next month.

Last edited by earthad1; 01-07-2009 at 01:10 PM.
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Old 01-07-2009, 01:12 PM   #20
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


got any website that shows gable ends ruin soffit ridge vent systems?
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Old 01-07-2009, 03:27 PM   #21
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


alot of this type talk in the roofing page,,,right here. Lots of roofers and experts on how and why's of doing what.

MOST say to take your soffit material(whether it is vinyl or alluminum material OFF and take off ALL soffit plywood "completely"and reinstall continous vented soffits AFTER making sure rafter bays are open and air flowing with aid of styrofoam baffles,,,then your ridge vents work right AND block off any gable vents!! Most guys there say the mushroom style or turbine style vents dont really work worth a hoot.
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Old 01-07-2009, 03:49 PM   #22
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Here's a good article about ventilation! Very informative!

http://www.cmhc-schl.gc.ca/en/co/mah...gemare_001.cfm

Consumers > Maintaining a Home > General Maintenance and Repair > Attic Venting, Attic Moisture and Ice Dams
The following fact sheet is part of the About Your House — General Series




Attic Venting, Attic Moisture and Ice Dams

It is rare for Canadians to visit their attics. For many years building codes have required high levels of attic insulation, making attics less-than-hospitable places. People usually go into their attics for one of two reasons: animal intruders, such as bats or squirrels, or water leaking through the top floor ceiling. This guide deals with water entry, such as roof leaks, ice dams, and attic condensation. Consult your local pest control expert to rid the attic of creatures.


Where to look for leaks

  • around plumbing stacks or plumbing walls
  • chimneys through the attic
  • any light fixtures from the ceiling below
  • electric wiring
  • ducting for fans or heating systems
  • perimeter walls
  • partition walls
  • party walls
  • above pocket doors
  • above lowered ceilings
  • where the side of a cathedral ceiling meets an open attic
  • split level discontinuities
  • where additions meet an older section of the house
  • above rounded corners or staircases
  • balloon frame walls

Figure 2: Leakage areas on split level houses
Attic Venting

If you have properly sealed the attic you should not need more attic ventilation. Attic ventilation is overrated.

Recent research shows that identical attics, with one unvented and the other vented to code, have much the same humidity and temperature. Attic computer models show that attics in damp coastal climates may actually be drier with less ventilation.
Building codes require attic ventilation. Ventilation may make a difference in a borderline situation. Attic ventilation is driven primarily by wind. To ensure thorough venting, have openings at the soffits and then higher on the roof at the ridge, gable end, or high on the roof surface. The requirement for attic vent sizing is nominally 1:300

Last edited by Wildie; 01-07-2009 at 04:07 PM.
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Old 01-07-2009, 04:59 PM   #23
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Don't forget, attic ventilation is also for summer, to keep the heat down in the attic, which keeps the house cooler as well as prolongs the life of your shingles.
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Old 01-07-2009, 07:00 PM   #24
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


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Originally Posted by Wildie View Post
Here's a good article about ventilation! Very informative!

http://www.cmhc-schl.gc.ca/en/co/mah...gemare_001.cfm


Attic Venting

If you have properly sealed the attic you should not need more attic ventilation. Attic ventilation is overrated.

Recent research shows that identical attics, with one unvented and the other vented to code, have much the same humidity and temperature. Attic computer models show that attics in damp coastal climates may actually be drier with less ventilation.
Building codes require attic ventilation. Ventilation may make a difference in a borderline situation. Attic ventilation is driven primarily by wind. To ensure thorough venting, have openings at the soffits and then higher on the roof at the ridge, gable end, or high on the roof surface. The requirement for attic vent sizing is nominally 1:300
This is a crazy article. Not sure I buy that you don't need any ventilation. or as they said: "with one unvented and the other vented to code, have much the same humidity and temperature." crazy.
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Old 01-07-2009, 08:15 PM   #25
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


There are OTHERS who say inadequate attic vents lead to 'cooking ' the shingles from below,,alot like frying a egg on it, they claim much reduced shingle life.
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Old 01-07-2009, 09:36 PM   #26
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


I live in Canada, but haven't read this info.

We currently have federal and provincial rebates for increasing attic insulation to a max of R50. The ECOENERGY website and others I have been to discuss the house as a system, as in attic ventilation as a system.
I have lived here in -55 F winters and + 100 F summers and I am now nestled between the Great Lakes. My shingles baked on the west side of my house within 12 years with only 3 roof top vents and underspec soffit ventilation for my 700 foot attic. In addition my top floor was an oven in the summer, cool in the winter. Although I don't visit there much but I can assure you on a hot summer day prior to improving the rooftop venting it hit 130 degrees. Because we ahve basements we don't inhabit most of our attics nor put much HVAC stuff up there
Ice dams continued to form on my East facing valleys until I upgraded insulation and increased soffit ventilation in my plywood soffits and added baffles between the rafterslast month. We have had in excess of 24 inches of snow since Dec 24th and NO ICE DAMS.

BTW over the December billing period my gas consumption in cubic feet has dropped by 25% over last year same period with SAME AVERAGE temp, Same programable T stat , same settings with same MID E furnace. So IMHO this stuff works.

I am offering several remaining well baked shingles found on my last visit to the atticfree to any doubters, you pay the shipping.
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Old 01-07-2009, 09:38 PM   #27
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Forgot to mention, the roofers said an under ventilated attic would fail to qualify for any warranty claims on the new 40 year shingles....
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Old 01-07-2009, 09:49 PM   #28
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Quote:
Originally Posted by Andrew Whitehead View Post
if you are getting that much condensation in your attic, did you make sure that you had a proper vapour barrier down before you had the insulation blown in? If not, the insulation maybe slowing the heat loss, but he moisture is still going through the same as before, if not faster since the inside of your house is warmer.
It is not wise to put any vapor barrier in an attic. Moisture rises and it is supposed to be allowed to leave the house as being contained it will cause problems. The basement under the slab and on the walls is the only place to install a vapor barrier. Proper venting will carry the moisture away. Gable vents aren't as good as ridge venting because they can't remove enough air in a constant flow across the underside of the roof sheathing to really do the job that is needed.
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Old 01-07-2009, 09:54 PM   #29
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


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Originally Posted by Baron View Post
It is not wise to put any vapor barrier in an attic. Moisture rises and it is supposed to be allowed to leave the house as being contained it will cause problems. The basement under the slab and on the walls is the only place to install a vapor barrier. Proper venting will carry the moisture away. Gable vents aren't as good as ridge venting because they can't remove enough air in a constant flow across the underside of the roof sheathing to really do the job that is needed.
I've read the same information about vapour barriers in attics somewhere, and it makes sense to me not to have them. but I've also read where you can have them, so its conflicting information I guess.
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Old 01-07-2009, 09:55 PM   #30
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oops, double posted

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