Proper way to install roof vents?


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Old 10-06-03, 08:24 PM
cheapfurcoat
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Proper way to install roof vents?

I have a shingle roof. I have 4 roof vents and ridge venting that I need to install.

Is there a way to install a roof vent without having to buy more shingles? I guess the best way to ask is. How do I carefully take out shingles for a vent without damaging surrounding ones? Before or after I cut the hole?

When installing ridge venting (the 4 foot sectional kind), can I re-use the old ridge shingles on the new ridge venting?

My roof is only 4 years old and in good shape. I need the vents for proper attic ventalation.
 
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Old 10-07-03, 06:53 AM
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First, take the vents other than the ridge vents back and trade them for enough shingles to cut up for the ridge cap. Ridge vents, installed with a correct "cut-back", and correct soffit vents are all you need for proper ventilation. Make sure the soffit vents have a clear path for the air to travel to the ridge, no insulation in the way.

You won't be able to salvage the old ridge cap. Go buy a new circular saw blade (with carbide inserts) before you start, because cutting back the decking will pretty much hose your old one.

Good luck

Frank
 
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Old 10-07-03, 10:40 AM
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button vents

You dont need more shingles here you can just work the button vents right under the shingles. For get the ridge vents they dont work to good we have found. ED
 
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Old 10-07-03, 11:59 AM
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Ridge vents with soffit vents are the most efficient and the preferred method of ventilation by the manufacturers.

Ridge vents along with roof vents is actually a detriment to attic ventilation.
 
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Old 10-07-03, 01:11 PM
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the preferred method of ventilation by the manufacturers.

But not buy the US Government on the gov. www. ED
 
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Old 10-07-03, 05:39 PM
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Originally posted by Ed Imeduc



But not buy the US Government on the gov. www. ED
Fair enough.
But the government isn't the one giving the warranty.
How did you put that smiley in there?
 
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Old 10-08-03, 09:09 AM
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Thumbs up Smilies

Look over on the left here when you post just click on one and its in the post for you Ed
 
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Old 10-09-03, 01:14 PM
Caspertg
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"You dont need more shingles here you can just work the button vents right under the shingles. For get the ridge vents they dont work to good we have found."


I completly concur.
I am assuming you are using gravity vents (whirleybirds). Cut the whole, slide the top and both sides under the existing shingles (the base of the vent should be bent on the very end at about a 160 degree angle to channel any water that might slip in down and out) You have to be very carefull to not break the shingles when you bend them up to nail the vent. Get some plastic cement and put a thin layer underneath the shingle for added piece of mind.


Paul
 
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Old 10-09-03, 03:52 PM
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Let's get back to basics:

1. For air to flow out the top (ridge) through convection (I think that's the right term) it must first come in the bottom (soffit). Without inlet you ain't going to get any outgo.

2. If whirlybirds "whirl" to take the heat out, how come on the hottest days they ain't budging, but on cold, windy days they are whirling like crazy?

3. There's an optimum amount of "vented area" (square feet of ventilation per foot of attic floor space). I used to know this but IIRC it's around 1 square foot of vent for 100 square feet of attic.
I also think that it's supposed to be divided into 1/2 intake and 1/2 vent.

A whirlybird is 12" inch diameter, using the formula: area = pi X the radius squared, then a whirlybird has 113 square inches of area, or .785 square feet.

If my memory is correct about the above, then an 1800 square foot of attic space house would need 18 square feet of vent, 9 square feet of exhaust and 9 square feet of intake. At .785 square feet per whirlybird an 1800 square foot attic is going to need 11 1/2 whirlybirds. So if your house is 64' X 28' your 64 foot ridge is going to have a whirlybird EVERY 5 FEET. Not very aesthetic IMHO. Particularly when THEY DON'T VENT THE ATTIC.

Frank
 
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Old 10-10-03, 04:53 AM
Caspertg
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Ok, first off my expertise is in Commercial roofing, not residential. I do know the basics though.


If a whirleybird is not spinning on a hot day, then it is malfunctioned. I installed 2 in my home and the spin like crazy in the summer. Simple physics, hot air rises.

I will go pull a book on what the suggest for attic venting, and give a more informed answer later today hopefully.


Paul
 
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Old 10-10-03, 08:39 AM
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Vents

Paul Book is Attic Sq ft X 0.7 = cfm
1 Sq ft for 150 Sqft attic

or 1 Sq" per Sq ft Attic

1/2 in 1/2 out

If you have a good V/B then they say you need only1 Sq ft per 300 Sq ft in the attic. I like the old way and look at the roof as just some thing to be there to keep the rain and snow off the insulation and thats all.

The turbine's: Have use them and gave them a try. Dont like them they just dont work out as they should. Sometimes they let the rain in. We like to use power vent fans for the attic on a tstat. Where else can you get about a 1/2 ton of A/C for just a few pennies per day.

just my .02 cents Hey that can run my vent fan for 2 or 3 days
ED
 
 

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