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-   -   Attic venting for small hip roof? (http://www.diychatroom.com/f9/attic-venting-small-hip-roof-73338/)

kevsmith 06-10-2010 11:57 AM

Attic venting for small hip roof?
 
I have a small in-law unit in back that currently has no ventilation. It's about 400 sq. ft., probably a detached garage conversion, and has a hip roof. So I have no soffits, no gables, and the ridge is about 2.5 feet long. We don't get any extreme winters but summer gets hot. What would be the best way to ventilate the attic, preferably DIY and not really expensive. Thanks for the help.

Ed the Roofer 06-10-2010 03:12 PM

Install continuous soffit vents around the entire exterior perimeter for the intake ventilation, unless you are planning on installing a new roof in the near future, in which case I would consider Smart Vent, which is an under shingle Intale Ventilation System that I like to use.

For the exhaust, a Solar Powered powered attic ventilator would be your easiest option to consider.

Ed

kevsmith 06-10-2010 05:48 PM

Thanks for the reply Ed, my only problem is that there isn't much of a soffit to work with. It looks like the roof just overhangs maybe an inch from the building, and most of that is shingle. I'm not really familiar with any of this so maybe I am missing something.

Yoyizit 06-10-2010 06:20 PM

Sounds like you'll have to pull air in one roof vent at one end and exhaust it through another at the other end.

For the attic volume the Web has calculators for the volume of a square-based pyramid and the roof volume can probably be calculated by using these formulas.

kevsmith 06-10-2010 07:25 PM

Thanks Yoyizit, so can I just use a square vent (usually for outflow) for intake low on one side and then use a power vent higher on the opposite side to draw air out?

Yoyizit 06-10-2010 07:50 PM

Quote:

Originally Posted by kevsmith (Post 454269)
Thanks Yoyizit, so can I just use a square vent (usually for outflow) for intake low on one side and then use a power vent higher on the opposite side to draw air out?

I don't see why not but you should figure out how many air changes per hour you want for this attic. You'll probably need to know the fan curve for your power vent to size the intake vent for the CFM you want.

http://www.google.com/search?client=...UTF-8&oe=UTF-8

handy man88 06-10-2010 08:20 PM

Quote:

Originally Posted by kevsmith (Post 454209)
Thanks for the reply Ed, my only problem is that there isn't much of a soffit to work with. It looks like the roof just overhangs maybe an inch from the building, and most of that is shingle. I'm not really familiar with any of this so maybe I am missing something.

You may want to consider these, although I would caution you that I think these could result in water intrusion if there is ice damming.

If this house does not have gutters, then ice damming shouldn't be a concern.

http://www.airvent.com/homeowner/pro...-theedge.shtml

kevsmith 06-11-2010 11:20 PM

Thanks for all the help everyone. I'll figure out how much air I need to move and go from there. By the way, any solar powered fans that anyone recommends?

handy man88 06-11-2010 11:53 PM

Quote:

Originally Posted by kevsmith (Post 454942)
Thanks for all the help everyone. I'll figure out how much air I need to move and go from there. By the way, any solar powered fans that anyone recommends?

Costco sells a solar powered attic fan.

kevsmith 06-12-2010 12:27 AM

I saw one there a couple of weeks ago. I think it was $299. It looked a little better than the Home Depot ones. Do you have any experience with that particular fan?

handy man88 06-12-2010 08:09 AM

Quote:

Originally Posted by kevsmith (Post 454964)
I saw one there a couple of weeks ago. I think it was $299. It looked a little better than the Home Depot ones. Do you have any experience with that particular fan?

I considered putting one in....the only issue with these fans is that they shut off when there's no sun.

Otherwise, it's cost free to run, and they operate year round.

I recommend you read the reviews on their website, which are almost all good.

Yoyizit 06-12-2010 11:10 AM

These solar fans seem to be putting out an awful lot of CFM for very little watts in.
They seem to be off by a factor of 5, in favor of the fan manuf.
I don't believe their numbers.


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