Home>Discussions>INSULATION & HVAC>Do I need a roof vent? Should I have one with no insulation in attic?
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chaz7979
Do I need a roof vent? Should I have one with no insulation in attic?

I live in a 100+ year old home, that by all accounts, has never had any kind of ventilation in the attic. The problem now is we have a modern roof with modern airtight materials and the attic is hotter than the blazes of hell in the summer. Adding to the confusion, we have no insulation in this very large attic but we do have barnboard floors and some old knob and tube in the ceilings below so we can't just blow in some insulation (at this point).

So my question is... if we do install a ridge vent to save on cooling and extend the life of our roof, will we be significantly adding to our heating costs in the winter? Is there a better venting system that allows for seasonal use? For instance, open in the summer but, closed in the winter? BTW, we have never had issues with ice dams, rot, or mildew.

Thanks in advance for the advice.

junkout
Re: Do I need a roof vent? Should I have one with no insulation in attic?

a ridge vent alone will do nothing you need ridge and soffit vents and insulation. or you can insulate the bottom of the roof deck and seal the attic making it a conditioned space. but this will not help the life of your roof any.

dj1
Re: Do I need a roof vent? Should I have one with no insulation in attic?

junkout is right, you need an air flow in the attic.

chaz7979
Re: Do I need a roof vent? Should I have one with no insulation in attic?

Soffit vents are a given, I didnt think I had to be that explicit. The original questions still stand.

junkout
Re: Do I need a roof vent? Should I have one with no insulation in attic?

ok but the fact is that ventilation is as important in the winter as it is in the summer your attic either needs to be conditioned space with the roof insulated or you need attic insulation and ventilation just gable vents might even be enough. but if you seal it up in the winter with no insulation the snow will melt at the top where the warm air is run down till it reached the cold edge of the roof and freeze again causing an ice dam.

Dobbs
Re: Do I need a roof vent? Should I have one with no insulation in attic?

Chaz,

I agree with junkout and dj1; your eventual goal before the snow flies is to update the knob & tube wiring & get some insulation blown into the floor of the attic; this will allow you to keep the attic space cold so no ice dams will form on the lower outside roof.

To alleviate the heat now, you can install a ridge vent to complement the soffit vents, or you can install gable vents on either or both gables; you'll spend a ton of money for AC if you don't.

Google "How to calculate and install attic ventilation part 1 Youtube" for a video by Iris Communications to get a rundown on how to calculate how much ventilation you need for your particular roof; also check out http://www.thisoldhouse.com/toh/video/0,,20047003,00.html for a nice solar fan install by Tom Silva.

chaz7979
Re: Do I need a roof vent? Should I have one with no insulation in attic?
junkout wrote:

but if you seal it up in the winter with no insulation the snow will melt at the top where the warm air is run down till it reached the cold edge of the roof and freeze again causing an ice dam.

Except no it wont because there haven't been vents or ice damns in over 100 years.

Again, as I said in my first post to start this thread "we have never had issues with ice dams, rot, or mildew" and there has never been any vents.

Don
Re: Do I need a roof vent? Should I have one with no insulation in attic?
chaz7979 wrote:

Except no it wont because there haven't been vents or ice damns in over 100 years.

Again, as I said in my first post to start this thread "we have never had issues with ice dams, rot, or mildew" and there has never been any vents.

Something has changed, though...

"The problem now is we have a modern roof with modern airtight materials..."

junkout
Re: Do I need a roof vent? Should I have one with no insulation in attic?

my thoughts exactly daspyda

chaz7979
Re: Do I need a roof vent? Should I have one with no insulation in attic?
daspyda wrote:

Something has changed, though...

"The problem now is we have a modern roof with modern airtight materials..."

And have for over 30 years. Recently put on another new roof 5 years ago, still no ice dams or issues.

The only issue I have is that the attic is hot in the summer... really hot. I'm looking for a way to vent that heat in the summer but preserve what very little there is in the winter.

I was thinking maybe there was something like a vent that manually closes or works at a certain temperature but, I'm guessing by the responses that these things must not exist.

function
Re: Do I need a roof vent? Should I have one with no insulation in attic?
chaz7979 wrote:

I was thinking maybe there was something like a vent that manually closes or works at a certain temperature but, I'm guessing by the responses that these things must not exist.

Powered fans with a thermostat are actually common. I think self closing vents louvres can be had to accompany them. Just search powered attic fan an you will find those with a thermostat mixed in the results.

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