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Old 02-07-2011, 10:14 AM   #61
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Quote:
Originally Posted by Wildie View Post
It appears to me that water is coming through the roof above the gables.
Is the roof in good shape above this, or perhaps the ridge vent is short of the fascia and isn't sealed in a way that prevents water from entering?
You haven't shown the soffit venting in these pics.
I would think that you need to have some method of keeping the insulation blocking the flow from the soffits.
Frost forming on the underside of the roof sheeting is a sign of warm, moist air infiltrating from inside the house.
It may be coming into the attic by way of electrical boxes in the ceilings below.
Thanks for the reply Wildie.

The roof seems to be in good shape, and that's what I'm hoping is not happening, but I agree that it does look like water seepage then turning to frost. But its on both sides.

There is a gap between the ridge vent and the end of the roof. (I'd say about 1 1/2 feet on each side)

I've sealed off the attic hatch quite well (if you look at the older pics, you'll see frost above the hatch, now there is none) the frost used to extend all the way up to the ridge vent. Now, it seems prevalent near the soffit openings. There is none near the top of the attic but the wood did feel damp (though I don't know if that's the cold making it feel damp to my touch or that its actually damp)

I had the contractor who blew in the extra insulation add insulation to block off the soffits and placed those foam true vents in an attempt to guide the cold air from the soffits up sheeting and out the ridge vent. He checked and confirmed the soffits are not being blocked by insulation. Even though this has been installed, it still doesn't seem to be working.

So I'm going to need to lift the batten to looks for these electrical boxes. I don't have recessed lights. I have 3 bedroom lights, and hallway light the bathroom light it mounted to the wall, not the ceiling. There is a metal pipe in my son's room that used to feed duct work that ran into the attic when my air exchanger was up there... All that has been removed. I'm going to remove that pipe and seal/insulate the hole going into the attic as this may be a source of heat loss into the attic.

Being that the frost is so low, near the soffits, to me, it appears like the air is just not flowing properly.

I have a lower attic, but I haven't checked it yet. Its never given me as many problems as this one has. The lower attic consists of the kitchen and the living room. The upper attic consists of 3 bedrooms and a bathroom.

My bathroom fan venting out to the sealed gable in an insulated duct.



Another shot of the truevents



What do you suggest to use to seal off air leaks? Expanding foam insulation? I have a full can of "Great Stuff" kicking around somewhere.

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Old 02-07-2011, 12:35 PM   #62
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Where does the condensed water from the exhaust fan go? It's my understanding (and I admit I'm no expert) that you want to have the initial upward travel of the vent to go high enough that any water that condenses will trickle down and out of the house rather than sitting in the pipe or dripped back down into the house or attic? That looks like a direct path upwards and then curving to the vent. I suppose if it is short enough to stay warm you might not have a water problem from condensation, I'm sure that insulation helps a lot?
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Old 02-07-2011, 12:40 PM   #63
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


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Where does the condensed water from the exhaust fan go? It's my understanding (and I admit I'm no expert) that you want to have the initial upward travel of the vent to go high enough that any water that condenses will trickle down and out of the house rather than sitting in the pipe or dripped back down into the house or attic? That looks like a direct path upwards and then curving to the vent. I suppose if it is short enough to stay warm you might not have a water problem from condensation, I'm sure that insulation helps a lot?
no you're right, I need to figure out a way to mount it so it travels down... currently it runs alongside the attic floor and then goes up to vent... not the right way.

I just called a roofer and he said my frost is being caused by my ridge vent being blocked off by snow and its not breathing.... I'm thinking this is not the problem... though we've had HUGE amounts of snowfall this year... I guess it would not hurt to go up and remove it all? My issue with this is that he's pretty much saying a little frost is normal when I know for a fact that its not!


EDIT: In regards to the duct, how would I do this? if the duct enters the attic at a lower point than the exhaust, what's the best configuration to have it trickle out the gable end?

Last edited by earthad1; 02-07-2011 at 12:45 PM.
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Old 02-07-2011, 01:00 PM   #64
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


EDIT: In regards to the duct, how would I do this? if the duct enters the attic at a lower point than the exhaust, what's the best configuration to have it trickle out the gable end?[/QUOTE]

Attaching a very simple picture. Someone correct me if I'm wrong, but I understand the best way is to use rigid duct work with a straight run up and a sloping straight run slightly downward to the exhaust port. Install it, put in supports as needed, tape the joints and then get that insulated sleeve back overtop of it.

Regardless of the exact shape, I gather the core principals are a) Keep resistance to a minimum (use rigid pipe not flexible), b) As few turns as possible (each one dramatically reduces drag, although not as much as using flex duct) c) make sure you're sloping downward with as few turns as possible before it is going to start to condence.
Attached Thumbnails
Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation-vent-config.jpg  

Last edited by wilsonstark; 02-07-2011 at 01:03 PM.
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Old 02-07-2011, 01:20 PM   #65
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


This is how I have it currently



Needs to be the opposite. Use wire and give it a slow grade up, then back down into the exit?

EDIT: I'd be worried water would run back down into the bathroom fan

Last edited by earthad1; 02-07-2011 at 01:28 PM.
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Old 02-07-2011, 01:33 PM   #66
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


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Originally Posted by earthad1 View Post
This is how I have it currently



Needs to be the opposite. Use wire and give it a slow grade up, then back down into the exit?

EDIT: I'd be worried water would run back down into the bathroom fan
The air is warmest the closest to the fan, and the pipe will be warmest as well. As long as your horizontal run is downward sloping I can't imagine any water coming down the fairly short vertical run from the fan. Much more importantly none will be sitting in the horizontal run, growing icky stuff.
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Old 02-07-2011, 02:04 PM   #67
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Like this?

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Old 02-07-2011, 03:28 PM   #68
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Steepest possible up slope that still allows just one elbow and a gradual slope downwards. I don't have a paint program on my phone might try to do it later.
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Old 02-07-2011, 03:50 PM   #69
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Quote:
Originally Posted by earthad1 View Post
Like this?

The optimum way to run the bath ductwork is to run it verticly as possible from the fan, to a point slightly higher than the gable vent. Then, run it downhill to the vent.
The idea being that any moisture from the bathroom that condenses, will run out the gable vent, rather than back into the fan.
In my home the fan is vented verticly, all the way out through the roof and I have never experienced a problem with it.
Its a only a 4 foot run, so I assume that the moisture laden air is vented before it condenses.

As for the frost that is still forming, perhaps the ridge venting isn't adequate and you may require a couple of mushroom vents to suppliment it.
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Old 02-07-2011, 07:45 PM   #70
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Looks to me that your true vents are not done properly. The insulation on either side of them is blocking potential ventilation air from your soffit vents, apparently by as much as 50%! The true vents should be installed across the full width of the rafter bays to ensure maximum draw from your soffits.

Also make sure your soffit vents are adequately sized. Around here it needs to be a minimum of nine square inches per foot of net free vent area. Exceeding the minimum here will do no harm. The idea is to make the soffit vents the easiest place for air to enter the attic to replace that which escapes out the ridge. That guy with the drill in the one photo is just wasting time. Your ridge vent needs to be spec'd at slightly less that twice what the soffit vents are spec'd as the ridge vent services soffits on both sides of the house. The space seen in your sheathing for the ridge vent looks rather small for this. Keep in mind the material used for the filter in the ridge vent also takes away from net free vent area as well. If the soffit vents are constricted, as your are, make up air will be drawn in through the ceiling from your living spaces. This is also why the soffit vents should be slightly larger than the ridge vent.

A vapor barrier is essential, IMO, to prevent moisture from traveling up through the insulation. The top few inches of insulation are as cold as the rest of the attic and water vapor can condense on insulation as easily as on wood framing members. Damp or wet insulation severely reduces the R factor and takes forever to dry out, especially with inadequate ventilation. Ideally, the vapor barrier should be six mil poly sheeting installed directly behind the finished ceiling.
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Old 02-07-2011, 10:51 PM   #71
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


I agree with mem except on the vapor barrier. Find your location on page 26, read page 28; http://www.nuwool.com/pdf/VaporBarrierJournalPaper.pdf

Your ridge vent is only Ĺ cut, as mentioned. The baffle is too small, compare to this 25 sq.in.; http://www.bergerbuildingproducts.co...Attic_Vent.pdf from HD.
Or Lowe’s at 19- sq.in.- cut for 16”o.c. would be 9sq.in., the recommended minimum. http://www.adoproducts.com/duro.html Someone cut yours to the 16" size when they should have used them full width for 24"o.c.


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Old 02-08-2011, 01:22 AM   #72
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Quote:
Originally Posted by Wildie View Post
The optimum way to run the bath ductwork is to run it verticly as possible from the fan, to a point slightly higher than the gable vent. Then, run it downhill to the vent.
The idea being that any moisture from the bathroom that condenses, will run out the gable vent, rather than back into the fan.
In my home the fan is vented verticly, all the way out through the roof and I have never experienced a problem with it.
Its a only a 4 foot run, so I assume that the moisture laden air is vented before it condenses.

As for the frost that is still forming, perhaps the ridge venting isn't adequate and you may require a couple of mushroom vents to suppliment it.
Agreed about going out through roof, at least in theory, but that has to be done REALLY correctly or frost is the least of your worries. For a DIYer I'd say at least temporarily avoiding more holes in your roof might be wise.

I've tried to illustrate the point for the OP. Again, go as straight up as you can while still leaving the horizontal pipe with enough fall for condensed moisture to drain out of the house.
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Old 02-08-2011, 06:22 AM   #73
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Wow, thanks for all the help on this guys!!! Your feedback is excellent and very much appreciated.

Quote:
Originally Posted by Wildie View Post
The optimum way to run the bath ductwork is to run it vertically as possible from the fan, to a point slightly higher than the gable vent. Then, run it downhill to the vent.


Yea, I can get a vertical run by using the attic floor, but the gable is higher than the attic floor, that’s the hard part…so if I do as low as a slope as I possibly can, get it higher than the opening in the gable, then direct it downward out to the gable, it should work?

What if I run it vertically on the attic floor, cut out a circle in the soffit, and vent it out that way?

Quote:
Originally Posted by mem View Post
Looks to me that your true vents are not done properly. The insulation on either side of them is blocking potential ventilation air from your soffit vents, apparently by as much as 50%!


I though you needed to block that off for those vents to work properly. Should I just remove that yellow insulation he put there?

Quote:
Originally Posted by mem View Post
The true vents should be installed across the full width of the rafter bays to ensure maximum draw from your soffits.

Those were the widest ones we could find…lol so you’re saying maybe double them up?

Quote:
Originally Posted by mem View Post
Also make sure your soffit vents are adequately sized. Around here it needs to be a minimum of nine square inches per foot of net free vent area. Exceeding the minimum here will do no harm. The idea is to make the soffit vents the easiest place for air to enter the attic to replace that which escapes out the ridge.
My soffits are open all around the house. I’m going to replace these ones this summer when I replace the ridge vent with a higher quality one. I have the old machine punched aluminum soffits which don’t seem to be as effective as the straight hole punch ones (though would that not allow water to enter?)

Quote:
Originally Posted by mem View Post
That guy with the drill in the one photo is just wasting time. Your ridge vent needs to be spec'd at slightly less that twice what the soffit vents are spec'd as the ridge vent services soffits on both sides of the house. The space seen in your sheathing for the ridge vent looks rather small for this. Keep in mind the material used for the filter in the ridge vent also takes away from net free vent area as well. If the soffit vents are constricted, as yours are, make up air will be drawn in through the ceiling from your living spaces. This is also why the soffit vents should be slightly larger than the ridge vent.
I get it, so because my soffits are not working properly in drawing in the air from outside, my ridge vent is essentially sucking warm air from wherever it can from inside the house? Yea, now that you guys mention it, after looks at videos of people installing ridge vents, it seems that my openings are pretty small compared to what I’ve seen done.

Quote:
Originally Posted by mem View Post
A vapor barrier is essential, IMO, to prevent moisture from traveling up through the insulation. The top few inches of insulation are as cold as the rest of the attic and water vapor can condense on insulation as easily as on wood framing members. Damp or wet insulation severely reduces the R factor and takes forever to dry out, especially with inadequate ventilation. Ideally, the vapor barrier should be six mil poly sheeting installed directly behind the finished ceiling.
I’ve been told that a vapor barrier between the attic floor and the home’s ceiling is a huge no no in my area.

Thanks for the links GBR in WA, I’m reading them now!

http://www.bergerbuildingproducts.co...Attic_Vent.pdf

Definitely want these!!!!! So the idea is that they fit the entire width of the baffle and bend at the bottom eh? Cool! Wish I would have known about there. Would have saved me some $$$ in having this guy installed the wrong ones!!!!


Last edited by earthad1; 02-08-2011 at 07:14 AM.
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Old 02-08-2011, 10:03 AM   #74
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Quote:
Originally Posted by earthad1 View Post
Wow, thanks for all the help on this guys!!! Your feedback is excellent and very much appreciated.



Yea, I can get a vertical run by using the attic floor, but the gable is higher than the attic floor, thatís the hard partÖso if I do as low as a slope as I possibly can, get it higher than the opening in the gable, then direct it downward out to the gable, it should work?

What if I run it vertically on the attic floor, cut out a circle in the soffit, and vent it out that way?
I think you mean horizontally on the attic floor. And yes you can. Actually, this method might possibly be your best alternative. Just put a short straight section of duct vertically, tall enough so you can get a downward horizontal slope to the exhaust port. Keep the exhaust port in the gable end though, i.e cut a new hole. If you exhaust the vent near the soffits you run the risk of sucking that moisture right back into your attic through the soffit vents.

Quote:
Originally Posted by earthad1 View Post
Quote:
Originally Posted by mem
Looks to me that your true vents are not done properly. The insulation on either side of them is blocking potential ventilation air from your soffit vents, apparently by as much as 50%!


I though you needed to block that off for those vents to work properly. Should I just remove that yellow insulation he put there?

Quote:
Originally Posted by mem
The true vents should be installed across the full width of the rafter bays to ensure maximum draw from your soffits.

Those were the widest ones we could findÖlol so youíre saying maybe double them up?

Quote:
Originally Posted by mem
Also make sure your soffit vents are adequately sized. Around here it needs to be a minimum of nine square inches per foot of net free vent area. Exceeding the minimum here will do no harm. The idea is to make the soffit vents the easiest place for air to enter the attic to replace that which escapes out the ridge.


My soffits are open all around the house. Iím going to replace these ones this summer when I replace the ridge vent with a higher quality one. I have the old machine punched aluminum soffits which donít seem to be as effective as the straight hole punch ones (though would that not allow water to enter?)
As GBR notes it looks like those baffles were cut in half to, unbelievably, save material costs. Get the plastic ones you like from the berger link he posted (and maybe a new installer?). They are easier to work with in a retrofit when the nails are protruding from the underside of the deck. And the downward flap on them will prevent your blown in insulation from falling back into the soffit and plugging them up in the future.

When you replace the soffit vents, opt for a continuous type vent. They ensure balanced venting along the entire soffit run and are regarded as the most effective.

Quote:
Originally Posted by earthad1 View Post



Quote:
Originally Posted by mem
A vapor barrier is essential, IMO, to prevent moisture from traveling up through the insulation. The top few inches of insulation are as cold as the rest of the attic and water vapor can condense on insulation as easily as on wood framing members. Damp or wet insulation severely reduces the R factor and takes forever to dry out, especially with inadequate ventilation. Ideally, the vapor barrier should be six mil poly sheeting installed directly behind the finished ceiling.


Iíve been told that a vapor barrier between the attic floor and the homeís ceiling is a huge no no in my area.

Thanks for the links GBR in WA, Iím reading them now!
Normally I would be reluctant to disagree with GBR on anything as his advice is typically spot on. In regard to the vapor barrier though, I don't understand why he is not on board. The link he supplied clearly states the need for a vapor barrier in your neck of the woods. See page 27, points 5 and 6, and the chart on page 28 as well.
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Old 02-08-2011, 10:54 AM   #75
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Quote:
Originally Posted by mem View Post
I think you mean horizontally on the attic floor. And yes you can. Actually, this method might possibly be your best alternative. Just put a short straight section of duct vertically, tall enough so you can get a downward horizontal slope to the exhaust port. Keep the exhaust port in the gable end though, i.e cut a new hole. If you exhaust the vent near the soffits you run the risk of sucking that moisture right back into your attic through the soffit vents.
Sorry, that's what I meant...

Quote:
Originally Posted by mem View Post
As GBR notes it looks like those baffles were cut in half to, unbelievably, save material costs. Get the plastic ones you like from the berger link he posted (and maybe a new installer?). They are easier to work with in a retrofit when the nails are protruding from the underside of the deck. And the downward flap on them will prevent your blown in insulation from falling back into the soffit and plugging them up in the future.
Yup that's exactly what he did... Not knowing any better, I thought he did it properly.. They are just stapled in. Is that ok when I redo them? Just use staples ?

Quote:
Originally Posted by mem View Post
When you replace the soffit vents, opt for a continuous type vent. They ensure balanced venting along the entire soffit run and are regarded as the most effective.
I will thank you!

Quote:
Originally Posted by mem View Post
Normally I would be reluctant to disagree with GBR on anything as his advice is typically spot on. In regard to the vapor barrier though, I don't understand why he is not on board. The link he supplied clearly states the need for a vapor barrier in your neck of the woods. See page 27, points 5 and 6, and the chart on page 28 as well.
I'm in New-Brunswick, Canada, right above Maine (the border is about 2-3 hours) and I've never seen any newer homes used vapor barrier between the attic and the ceiling. I'll have to have a look and see though I'm like 90% sure this is nothing there. I was under the impression if you had one, if any moisture were to make its way up into the attic and his this vapor barrier, water vapor could then be deposited on the ceiling and cause damage to it.

Now, is a "Vapor Barrier" and a "Vapor Retarder" the same thing??


Last edited by earthad1; 02-08-2011 at 10:59 AM.
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