# Is there any rule of thumb for attic temps compared to outside temp?



## jkfox624 (Jun 20, 2009)

My house is a 1979 basic ranch style house and ive always had bad ice problems. After the worst winter we've had in a long time and the ice ripping the gutter and fascia board off my house i'd had enough. I only had R-19 up there added another 30 on top of it and noticed the old insulation was crammed right tight to the sheathing. I always saw that nice big 2 foot vented soffit out front thought it was doin something, guess not. Pulled gutter fascia down just to find the siding guys that did this before i moved in put the vented soffit over the solid wood soffit. Ripped the wood down, slid durovent up the rafter bays.

Question is it seems a ton cooler up there now, is there a temp difference thats needed? I would think anymore than say 10 degree difference would mean i still have to much heat loss and not enough air flow. I know i got enough coming up the rafters but 35' ridge length i just have gable vent on each end. I guess i should just ride it out another year to see how much it helped but its become a mission of mine to never have ice again.


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## WarnerConstInc. (Jan 30, 2008)

Basically, attic temp should be close to the outside temp.


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## PA woodbutcher (Mar 29, 2007)

Gable and soffit/ridge vent shouldn't be used together. The theory in this is that the gable vents interrupt the way the air flows from the soffits.

Warner is right that the attic should be close to the outside temp. Your insulating and heating/cooling the house, not the attic.

A good sign is when you open your attic in the winter and you don't see any "frost" on the nails poking through. The frost is frozen condensation from the warm air meeting the cold air and not ventilating if that makes sense. Before changing anything on a roof vent system I always inspect the attic and look at those protruding nails. During the summer you can usually see where the plywood/OSB is black around the nails.


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## jkfox624 (Jun 20, 2009)

I always thought it was your not supposed to use gable and ridge vent together because it can cause negative pressure and suck rain into the attic. Either way im trying to make the best with what i have atm. And yeah the nails are pretty rusty on the bottom, especially down near the eaves.


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## WNYcarpenter (Mar 2, 2007)

jkfox624 said:


> I always thought it was your not supposed to use gable and ridge vent together because it can cause negative pressure and suck rain into the attic. Either way im trying to make the best with what i have atm. And yeah the nails are pretty rusty on the bottom, especially down near the eaves.


The way I understand it, you and PAwoodbutcher are both right. I re-read your OP and it doesn't sound like you have ridge vents....just gable vents.

Everything you did this summer is gonna help tremendously....you know that already....IMO, for the best results, I would cut in a continuos ridge vent and seal off the gable vents.

I just did my folks' roof. They were having the same exact problems (same style house etc...). I did everything you you mentioned short of adding insulation....we cut in the ridge vent and sealed the gables....went from light gray to black shingles, with the thought that the dark shingles will melt the ice better on those 'thaw' days we get once or twice a winter!

Like you, I am very curious to see what will happen this winter!! I still have a couple more options if there isn't a sign of significant improvement.

It's also my belief that where are, there's always going to be ice on the roof.

You won't have long to wait!!....2nd week of November last year we got snow and it lasted 'till March:sad:


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## jkfox624 (Jun 20, 2009)

WNYcarpenter said:


> The way I understand it, you and PAwoodbutcher are both right. I re-read your OP and it doesn't sound like you have ridge vents....just gable vents.
> 
> Everything you did this summer is gonna help tremendously....you know that already....IMO, for the best results, I would cut in a continuos ridge vent and seal off the gable vents.
> 
> ...



Yeah i def agree at some point theres always gonna be ice around here, especially if you have gutters. I notice alot of houses with the southern exposure on those 32+ degree days get ice on one side and not on the other. I always figured it the was the sun heat snow melt, water runs down hits the cold gutter, freezes and the cycle just gets worse. Regardless of whether i can mix soffit and gable vents, i had to do something, the bottom 3 feet of plywood was starting to show signs from underneath that its life span is being shortened considerable. Hoping the increase air flow will dry it out.

In my 5 year plan i have a major reno i wanna do with a 600 sq ft addition off the one end with garage underneath. Hoping i could wait til then to cut ridge vent in main house when i redo the whole roof.


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## Morning Wood (Jan 12, 2008)

Another major problem you probably have is heat loss from your conditioned space (the living area) into the attic. You are leaking heat from your house into the attic. Now that you have better ventilation you are going to leak even more heat because of the increased air flow in the attic. Good ventilation in the attic is a good thing. Heat loss into the attic is not. Suck it up and get a blower door test. I bet you find quite a few air leaks that could be stopped up with spray foam. That will help keep your heat loss down and your heating expenses down too.


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## jkfox624 (Jun 20, 2009)

Morning Wood said:


> Another major problem you probably have is heat loss from your conditioned space (the living area) into the attic. You are leaking heat from your house into the attic. Now that you have better ventilation you are going to leak even more heat because of the increased air flow in the attic. Good ventilation in the attic is a good thing. Heat loss into the attic is not. Suck it up and get a blower door test. I bet you find quite a few air leaks that could be stopped up with spray foam. That will help keep your heat loss down and your heating expenses down too.



I dont think i have a huge amount of heat loss. I could have a 2 foot snow pack on my roof all winter. It was just the bottom 2 feet would all dam up in the gutter and get about 8 inches thick, then it would hang over the gutter. Plus before i added the extra R-30 overtop gas company readjusted my budget to $80 a month. To be able to heat 1k sq ft with finished basement, heat my water with 3 kids and a wife and cook on the stove for $960 year. So i cant have to awful much heat loss.


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## monkey (Jan 25, 2009)

No real answer for you're OP but what about opening up to the roof and adding a few skylights....
If collar ties need to stay wrap them in something that matches the rest of the house.....
insulate between bays and nothing to vent.
I like to dream big and am looking at my post and beam as I type...


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