Roof baffles/cellulose insulation

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burin

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First post, need advise on an insulation question.

My house has only 6-8" of cellulose in the attic, truss roof. I want to put an additional 6" of blow in insulation up there. My question is do I need to buy those foam thingies that go at the bottom of the roofline between the trusses to keep insulation off of the roof sheathing, or not. I don't have a soffit/ridge vent, attic is vented through the gable ends.

thanx in advance
 

Jadnashua

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Those channels are designed to keep soffit vents open. If you don't have any, they don't buy you anything.

Depending on where you live, another thing to consider is adding a radiant barrier to the underside of the roof trusses. this is basically a foil faced piece of craft paper. It reflects heat back through the roof in the summer, and back into the house in the winter...doesn't cost much, easy to install, and works. Doesn't matter if it is single or double sided foil, or perferated, either in most applications. Having reinforcement filaments in it helps keep you from tearing it while installing, and is useful.
 

burin

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Sweet. that's what i thought, but wasn't sure... I live in aurora, co. So, yea the radiant would probably help in the summer. I've figgured that I can add 6" for around 200$, so hopefully I can recoup the cost in 2-3 years on heating. Don't much run the central air in the summer (have a swamper) . too $$$
 

LiamM

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even though you don't have soffit vents now, it might be worth the cost and effort to install the baffles now. that way, if/when you decide to switch over to soffit and ridge vent, it'll be easier since you won't have to dig through 12" of insulation.

just my $0.02...
 

Leejosepho

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econguy said:
even though you don't have soffit vents now, it might be worth the cost and effort to install the baffles now ...

Yes, and now would also be a good time to add some soffit venting. A roof needs ventilation both in hot weather and cold.

Here is some info you should consider from a link someone recently posted for me:

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Winter Nemesis: Ice Dams

Ice dams are a common cold weather problem caused by snow melting over heated portions of a building and refreezing at colder portions of the roof, creating a dam. Water produced by subsequent melting then backs up under the shingles, eventually causing damage to insulation, interior finishes, and more. The snow melts due to heat loss into the attic from inadequate insulation, air leakage, and/or inadequate ventilation.

Suggested Remedies:
Install continuous soffit-and-ridge vent systems and baffles at lower side of the roof, providing at least a 2-inch space between insulation and sheathing.

http://www.toolbase.org/Design-Construction-Guides/Roofs/ice-dams
---
 
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burin

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I do understand that proper soffit/ridge venting is much better than the gable end vents I have now. Would installing soffit venting without doing a ridge vent have a noticeable effect? The gable vents are about 18" square, about 18" below the apex there are two of them, roof is 28x40, 4 pitch.
 

Leejosepho

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burin said:
Would installing soffit venting without doing a ridge vent have a noticeable effect?

That could depend upon what you mean by "noticeable", but adding venting in your soffit would certainly be an improvement. Our old house has gable vents similar to yours and no venting even possible in the soffit area without removing some of the 3-1/2†of insulation we have over the walls, and just yesterday we found mold under our shingles. Gable vents regularly compete for air from each other while roofs need a regular supply of air passing underneath them and on out. We ran out of time and money this year, but next year we will completely re-frame our roof.
 

Livin4Real

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another option is installing a power vent in one of the end gables. Some people put one on both ends then have one sucking air in and the other end blowing it out but this can be too much ventilation in the winter and have a negative effect on heating if your in a cold climate.
 

Jadnashua

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Solatube has some neat solar powered vents that can be used either as gable or roof. The solar panel can be remoted, if the desired location doesn't get good sun.
 

LiamM

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If you're springing for the soffits, any reason why you wouldn't do the ridge vent at the same time?
 

burin

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Yea, wouldn't do the ridge right away because house will need a new roof in 5-7 years. Would do it then. After thinking about this more, though, and looking at the house
_________
| H |
|________|
| G |
|____|

The attached (and uninsulated garage) gets rid of 1/4 of my available soffit venting area. So to properly do this, power venting might be the best solution. Roof has gable ends on left, right and over front (bottom) of garage.
 

Livin4Real

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It's nice if you can run a switch down to a hallway/closet for the power vent instead of in the attic, that way you don't have to worry about climbing in/out of the attic to turn it on/off.
 
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