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ridge vents vs. box vents vs. turbine vents

51852 Views 12 Replies 10 Participants Last post by  framer52
I recently re did my roof from light beige to grey shingles. two existing turbine vents were removed for aesthetics and a 15 ft ridge vent was placed at the top of my HIP roof. I live in Tulsa and immediately found that the up stairs A/C was not able to cool below 75 w/outside temp 103. The turbines worked fine before but I am trying to sell and box vents look better. The ridge vent is probably too small (15ft. on 1400 sqft of attic space). so my solution(the roofer is not much help) is to go ahead and have 4 box vents added for extra ventilation. I don't care what anyone says the turbine vents worked great for years. The just look ugly. I have R-38 in the ceiling and good soffit venting.
Anyone have any thoughts?
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Why only 15'? Why not the entire length of ridge? 15' is too little even with the best ridge vents at 18" NFA. Howmany feet of ridge vent could be installed.?
Thr "Right" answer regarding whether or not turbine vents or even static air musroom pot vents would work, or even a ridge vent for that matter, is the total NFVA of both the Intake and the Exhaust Ventilation systems proposed and installed.

Obviously, on your size home with only 15 feet of ridge venting available, you did not meet or exceed the "Minimum" Requirements, so now must add additional ventilation, which should have been devised prior to the roofing work being started.

What about Solar Powered Vents instead if the mushroom pot vents?

It goes against most principles to place two different ventilation systems for Exhaust, but your roofer screwed up prior to even starting, so what choices do you have now?

ridge vents vs. pot vents

my roof is pyramid shape or trapazoidal shape and the top ridge line is only 15 feet. I think one would get a real risk of water intrusion with putting ridge vents on the downward ridges. According to calcuations for an attic space of 1400 sqft, I need 2 square feet of venting on the top. Living in Tulsa and having dark shingles probably means I should be over 2. If 18 square inches per linear foot of ridge vent is a correct figure, I am at 1.87 sq ft.
You are right, my roofer screwed me. but he is willing to make it right. He offered to put back my two turbine vents or pot vents if I want. I thought about dormer vents and will certainly look into the solar powered. Putting 4 pot vents gives me 1.38 sqft. It seems reasonable that the pot vents and the ridge vent would give me what I need with some cushion. I think my basic question is whether pot or box vents will work as well as turbine vents in a hot climate.
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do you know what type of ridge vent is intstalled? I think 18NFA is what the best ridge vents are at. Many others are much less. Regardless, you clearly have a problem.
I've seen some houses in my neighborhood with a very high peak pyramid style roof. One in particular I'm thinking of has what looks to me to be less than a 10 foot top ridge. He has a ridge vent up there, and none down the side. I haven't looked at the back of his house to see if there are any other vents, but at least from the front side, I don't see any other vents and none down the sides. I'm not sure what the right solution would be for that owner.
Adding roof vents to existing roof

I have to say I am a big fan of quality ridge vent, the solid plastic kind with an external baffle. If the ridge vent you have isn't enough than you can't add pot vents or turbines or any other vent without removing it first.

I would recommend the solar powered vent as mentioned earlier in the thread
Along with your ridge vent, I would add two large box vents. One at either end of the hip ridge.
Or you could add a power vent for those hot summer days to exhaust some of the excess heat.

For more info

Recommend not mixing exhaust venting

I've seen the videos and heard the reasoning but, I don't think the cardboard mock up shows anything but air will come out of holes in the roof. I agree it will but it would be more telling if you could see where the air was coming from rather than going.

if you have a vent that "pulls air", next to a vent that does not, it is obvious what is going to happen. The site makes an argument that that ridgevents have filters and are shingled over, but they also have "net free area" ratings, same as soffits. Now in my mind NFA is NFA, and if the filters and shingles reduce NFA than the NFA would be reduced for that product. So really we have to products with NFA one is 1-2ft away ther other is atleast 15 ft away.

Thermal dynamics helps on days where the weather is really hot but on days where the outside temperature is close to the attic temperature, air will be pulled from the easiest/closest spot.

Now everyone is entitled to their opinon. and as long as there are no callbacks we have satisfied our customers needs.

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Your ridge is plenty for 1400 sq ft. and is the perfect shape for a ridge vent. The roofer should cut 3" of roof decking off of each side of the ridge giving you 1/sf of ventilation every 2". Your numbers were incorrect. Anyway you would only be able to span your ridge vent shy of the total legth so approximately 14 lineal feet. If you are still concerned that it is inadequate you could always install the ridge vent and have a power vent installed. A power vent runs off a thermostat connected to some power supply. If your attic space overheats the power vent turns on removing the hot air. An important note is that if you do not have adequate soffit ventilation or if your soffit vents are blocked with items such as birds nests, coverred with drywall or stucco or more commonly insulation (Blown in or batts) it wont matter what kind of ventilation you have on your roof. make sure your roof has adequate ventilation and you will assure your roof provides the usefull life the manufacturers claim . Especially shingle and metal roofs. Overheating of shingles leads to blisterring curling and shortens the lifecycle of any shingle roof and the axpansion and contraction due to heating and cooling of metal roofs will eventually lead to leaks as well
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Don't worry the house has been sold by now most likely.

3 year old thread....:whistling2:
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