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Old 09-03-2011, 12:36 PM   #1
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Attic Insulation

Hello All,

I have a few questions regarding attic insulation I am hoping can be answered here. I am having my whole roof redone at the end of October which includes the soffit, soffit vents and the wood behind the soffit installed. I am also having my attic insulated to code. I've had 2 contractors come and give me an estimate. I've asked them both about installing baffles so no insulation will get on top of the soffit vents.

The first contractor said they can install the baffles but I had another one come today and they told me they can't install them because the roof is too steep and they won't be able to get down to the area where the soffit is. Instead they want to dense pack insulation where the soffit vents are. I'm questioning this because doesn't this defeat the purpose of the soffit vents and then I won't have proper air flow in my attic?

Another question I have. When I do have the insulation done in my attic, I have an old attic fan vent. When the roof gets done, that is going to be taken out. When that is taken out, the wire that is left behind from the fan, do I need to completely take that out of the attic, or can I cap the wires off to prevent them from causing a fire?

Here are some pics of the fan vent and attic/insulation.

Here is the slope with the insulation over to the roof.

Another picture of the slope:

This is the wall with the gable vent and behind the wall is where the soffit vents are for the front of the house. The back of the attic has the same thing for the back of the house.

Here are 2 pictures of the attic fan wires.

I should also add that the plywood in the attic is being replaced as well.

Thank you to everyone who reads my thread.



Last edited by tim1218; 09-03-2011 at 12:38 PM. Reason: Grammar
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Old 09-03-2011, 08:55 PM   #2
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Thats pretty bad there. If you have soffit vents, no air is getting through them. The guy who said the baffles could not be installed, I would cross him off the list. I expect its going to be a real pain to do it. Because not only does he have to put the baffles in, he has to clean out the area too. The guy is going to be crawling on his belly, in a hot dustly attic, trying to clean out the area and put the baffles in. But the way I figure it, if you are in the insulation business, its part of the job.
A professional might have a vacuum that can remove the insulation from the soffits.
Actually, the slope doesn't look too bad from those photos anyways.


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Old 09-03-2011, 09:08 PM   #3
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Slope is not bad at all and the vents have to clear for proper air flow. Your attic looks very similar to mine.
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Old 09-03-2011, 09:46 PM   #4
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Another question is why are you taking out the attic fan? Your profile doesn't show where you live but if you have AC, removing excess heat from the attic with the fan (air coming in from the soffit vents) will help reduce the load on it! If you do end up removing it you can just mount a box and terminate the wires in it (be sure to put the cover on when you're done).
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Old 09-07-2011, 10:18 AM   #5
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You need to correct the ventilation. All the make up air that is getting out of the attic is largely coming from the home which = bad.

As far as the attic fan goes, they are not ideal.

Here is a report from Dominion Power on the subject.

Increased attic ventilation has long been promoted by roofing material and attic ventilator
manufacturers as a way to increase shingle life, decrease attic temperatures and lower cooling
costs. Unfortunately, there is no scientific data to validate any of these points and mounting
evidence and research to the contrary.
Attic ventilation was added to the nationwide building codes to prevent/eliminate roof damage
caused by trapped, moisture-laden air migrating into the attic during winter. This code change
followed the widespread introduction of indoor plumbing and central heating systems. As the
use of attic insulation increased, ventilation proved valuable in controlling another problem, ice
damming. Ice damming occurs when certain areas of the roof become warmer than others,
causing a thaw- freeze cycle that allows accumulated snow to melt, then re-freeze on colder
portions of the roof. This re-freezing creates an ice dam that works its way under shingles only
to later melt and create roofing leaks. Ventilation ensures the roof deck temperature remains
consistently cold so ice damming cannot start.
At some point, the original purpose for attic ventilation was forgotten and/or replaced, in cooling
climates, with the belief that it was to reduce roof and attic temperatures, thus lowering cooling
expenses and increasing shingle life. This was further compounded by the leap of faith that
increased or powered ventilation would be even better. While sounding logical, there is simply
no research to validate it. In fact, scientific testing has shown that attic ventilation has almost no
effect on roof surface/ shingle temperatures and very little effect on attic temperatures.
There is however, a growing list of research, computer modeling and field data that indicates
powered attic ventilation can be a detriment to health and safety and actually increase cooling
costs. The latest and most compelling findings by Natural Florida Retrofit and the AEC Applied
Building Science Center found that in all the homes they studied, powered attic ventilators
(PAVs) offered no benefits and sometimes caused serious health and safety problems. The
attached diagram shows just how PAVs unintentionally effect the house during operation. Their
research found three reasons why PAVs are not a good energy investment:
1. PAVs can create negative pressures in combustion appliances causing the back-
drafting of flue gases such as carbon monoxide in the living space. These same
negative pressures can also draw increased levels of moisture and soil gases, such
as radon, from the crawlspace.
2. PAVs can draw conditioned air out of the house and into the attic, causing the air
conditioning to run more. Conditioned air is then replaced with moisture laden outside
air, creating increased humidity levels inside the living space.
3. PAVs can increase utility costs substantially because of the increased energy
necessary to run the fan and cool/dehumidify the outside air being drawn into the
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