Vent Sure High Performance Slant Back Roof Vent

Alto · 07-01-2010, 11:50 PM

title on this should have been "VTS4-144 Owens Corning Roof Vent"

Does anyone have any experience with this vent? This seems like a very good alternative to a ridge vent, which will not work on my house. According to Owens Corning, you would only need 3 of these in a house of 1900 square feet of attic space, requiring around 450 NFVA.

I am not sure if this is a slant back vent; would that make a difference if my house is not very steep. otherwise, are there others with similar specifications (for around that amount of attic space.

Slyfox · 07-03-2010, 06:45 AM

I have used all of Owens Corning's vent styles except the ones your asking about. OC's website say's there only available in Cali- & Florida.

Alto · 07-04-2010, 06:22 AM

Thanks, I think I have solved the question of how I want to vent my attic; that is... do nothing and leave what I already have. Problem was that there was not enough space for a ridge vent. I measured the attic space from originall architect's plan for the house in 1954 and find 2400 square feet. Based on the interactive table at OC's web site I finally realized that the natural vents that i have are all that I need. There are 4 12" by 12" aluminum boxes on the roolf evenly spaced. I expect that that represents the 576 nfva that according to OC I need for 2400 square feet. since I am not sure if the old boxes will get torn up in the reroofing --not sure yet how they come off-- I called Owens Corning aboout replacing them . turns out that the model number for the ones that provide 144" in venting area I need have a different number. They are round aluminum natural vents (from the inside of my attic look like a portal with a screen over it) with 144" of nfva and are sold in Lowes.

According to what i have read these natural vents, placed evenly apart from one another, are nearly as effective as the ridge vent. (The measurements of my soffits seems to correspond precisely to the nfva suggested by OC) Actually, based on what I have read I have begun to wonder if because the pitch of my house is so low (is it correct to say that the 4/12 I see on the house's architectural plan is the pitch? I must only have 5 feet at its highest point) the 4 natural vents might even be better than the ridge vent. I have certainly begun to have some doubts about fans. both in terms of the cost to run them and the possibility of sucking conditioned air out of the rest of the house. So i think the natural vents --especially since because they are on the rear of the house and the way the house is set up cannot be seen-- is the best way to go.

Any advise for getting off the old boxes or roofing around them. The old shingles right around the vents seems to be OK. Can I just leave those fiew and put the new shingles over them? If taking the boxes off the vents is a problem do I have to tear them up or just leave those old shingles up there abd try to put new ones right over them under the boxes? If the boxes cannot be torn off it will not be possible to nail under them, but is this necessary?

How are the low profile vents? It seems like they would require a lot more cutting into the house and 9 or 10 vents for my house.

Slyfox · 07-04-2010, 08:15 AM

Assuming they aren't following apart due to rust/rotting etc., removing the existing shingles with out damaging the box vents should not be an issue.

I never recommend re-using flashing's, ventilation units, etc., but it can be done and I have done it before myself when the home owner requested I do so.
Just make sure your roofer is aware of your request before they start tearing off.

Alto · 07-04-2010, 01:06 PM

the metal boxes look like they are in good shape. Slight (if any) denting and a couple of spots with rust about the size of a nail head to the size of just under a quarter on each. I can probably use a rust inhibiting paint over them. Under the boxes it probably will not be possible to nail. You surely can push the shingles under there with no problem but no way to nail them down under the boxes,unless the boxes themselves can be raken off (I did try playing with them a bit but I couldn't budge them and did not want to bend anything. Looks like there is some kind of clasp but I can't move it. Unless you have a suggestion i will just go and look at them in Lowes.

The whole question of venting the attic is interesting. I had 4 roofers come to my house to give me an estimate. All of them reputable; at least one of them an OC certified roofer. I had 3 different stories; 1) put in a fan (and close the old boxes) 2) put in a ridge vent with some low profile vents or 3) close off the old boxes and put in a ridge vent. Not a single one measured the interior space of my attic and so far as i can see I am far off from what is needed for a ridge vent. Were they just counting on their experience? and if so they seem to have gotten it wrong (except for the guy with the fans, if you believe that fans do the job). Or is the question of venting not as important as i thought. After all, on the exterior a roof has to be able to cope with some 150 degrees or more. I wouldn't conclude that it is unnecessary to vent, but on the other hand it makes me want to rethink the question of venting for the sake of the roof. For the question of mildew and moisture build up that is another story.

I should add that i found that my utilities company has an depsatment of energy services or consumer affairs that was very helpful. i found them to be very knowledgeable and seemed to be well informed of studies dealing with ventilation and roofs. They might be an additional resource for people who have questions, though I am not sure all the utilities companies have such a department.