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Great discussions on ridge venting in previous threads. I cannot use a ridge vent because I have a hip roof and the vent is not long enough. I think I may need more exhaust/ridge venting. The attic temperature is consistently about 17-20 degrees higher than the outside temperature. No ice dam problems this year (but plenty of snow--live in Chicago area).

The attic is approximately 1700 square feet. If I use the 1:150 ratio, I need about 11.3 square feet of vent space. I have a lot of soffit vents (large overhangs--16x8 vents on all four sides). So I have about 8 square feet there. I have 9 mushroom vents near the ridge on the south side of the house. I think those are about another 3 square feet.

Do you think that more mushroom vents would help to equalize them to the soffit vents? Do you think that would lower the temperature? I have run out of room on the roof on the south side--can mushroom vents be installed on the north side without short-circuiting the flow?

Thanks for you input.
 

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11.3 in a balanced system is half in and half out. You can install hip vents, I am near Joilet, and would be happy to help you.
 

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Like Aaron said... half in half out. We know that we can't use ridge vent, and I have heard bad reports of hip vents taking in water.

If the mushroom vents are installed at the same height on the North as they are on the South then it should not short circuit the ventilation.

In my opinion the 15 sq ft guide line, is just a guide line. I state this because steeper roofs need more ventilation because of the actual cubic area of air space within the attic.

I am curious, if you didn't have an ice damn this winter; why are you messing with your ventilation?
 

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Lots of builders out here vent hips by cutting "notches" in the top corners of the rafters and thereby making a plenum along the hip, which carries air flow to vents at the ridge or mushrooms higher up.
Jim
 

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Discussion Starter #5
Grumpy said:
Like Aaron said... half in half out. We know that we can't use ridge vent, and I have heard bad reports of hip vents taking in water.

If the mushroom vents are installed at the same height on the North as they are on the South then it should not short circuit the ventilation.

In my opinion the 15 sq ft guide line, is just a guide line. I state this because steeper roofs need more ventilation because of the actual cubic area of air space within the attic.

I am curious, if you didn't have an ice damn this winter; why are you messing with your ventilation?


Thanks for the response. I agree, I have heard bad things about hip vents. To answer your question, I am messing with ventilation because I did have some condensation/frosting on the roof/nails this year and found that a bathroom fan had not been vented to the outside, but was blowing into the attic. While it was fixed, now I am nervous that it will happen again because the attic temperature is 20 degrees higher than the outside temperature. I may have dodge the ice dam bullet because I have large overhangs and oversized gutters. It seems like my only solution it to add about 6 new mushroom vents to try to equalize the vents. Do you think that will help?
Thanks.
 

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Whgat have you guys heard bad about hip vents? I have installed these many times, and with good roofing practice have never had a call back. At least twenty roofs of mine have it.

It all goes off attic floor space beccause hot air rises, and it gets faster as it goes up. You do not need additional venting in steeper roofs. I once pondered this. You do still need adequate ventilation.
 

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Hip Vents

Ever here of Mid-American Prouducts? They have a vent called Hip Master that works similar to ridge vents! I use them exclusively and have no complaint or call backs. :Thumbs:
 

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What type of vents are recommended for 200 MPH winds? My new roof is getting closer daily, I can almost smell the hot tar.
 

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200 Mph Winds

Teetorbilt said:
What type of vents are recommended for 200 MPH winds? My new roof is getting closer daily, I can almost smell the hot tar.
Teetorbilt you don't need a roof you need a shelter or water thight bunker!!
 
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