New Roof Coming - Edge Vents Or....?

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  #1  
Old 10-05-15, 12:58 PM
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New Roof Coming - Edge Vents Or....?

Getting a new roof for a 1906 3 story Victorian. Balloon framed. I'm in Minneapolis, land of extreme climate swings. The roof has box vents near the ridge but no soffit vents. It's extremely hot in the summer and extremely cold in the winter.

I asked the roofing company to install edge vents to do what the lack of soffit vents should be doing. Anyone have any information on the effectiveness of edge vents?

The other option would be to close the roof off entirely as I plan on finishing the attic but I don't know enough about all of this to make the call one way or the other.

Help, please!
 
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  #2  
Old 10-05-15, 04:40 PM
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OK what's edge vents?
Vents like these?
SmartVent by DCI - The #1 Choice for Attic Intake Ventilation
Opening up a whole can of worms finishing out an attic.
What size are the floor joist.
Does the windows meet local egress codes?
What size are the rafters?
Does the stairway meet minimum codes?
What's the plan for HVAC up there?
Make it a bedroom or add a closet and your going to be dealing with zoning, health dept as well as the building dept.
 
  #3  
Old 10-06-15, 10:24 AM
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Yes, those are what edge vents are.

But the question is about the effectiveness of the vents and the improvements in having a properly vented roof, not the can of worms that is finishing an attic.
 
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Old 10-06-15, 05:30 PM
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Does your roof edge get covered with snow that is piled into the gutters? The effectiveness of the vents may be diminished at a time when the ventilation is most important.

Although an eave vent approach may seem architecturally inappropriate on your vintage house, it would probably be the best approach.
 
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Old 10-06-15, 05:31 PM
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Don't know about up north but here in Florida roof vent area and spacing is specified by residential code. Have you checked?
 
  #6  
Old 10-06-15, 06:42 PM
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Hi JR,
Edge vents do work, but a Calvert points out, snow and ice can be an issue. There are several different styles like Air Vents "vented drip edge"
Vented Drip Edge - Air Vent, Inc.

In our northern climate having the vents farther under the drip edge seems like a good design. Whether it can be fitted to your house I do not know.

You mentioned balloon framing and your question is about attic ventilation, and those two can be related. The primary purpose of attic ventilation is to remove the excess moisture carried into the attic through leakage paths from the house. Those balloon pathways all need to be well sealed, it makes the ventilation work more effective.

There are guidelines for total attic ventilation and how much goes high and how much goes low. We can review that if you need.

Pictures would help.

Bud
 
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Old 10-07-15, 12:49 AM
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I'll show that drip edge to the roofer and see what he says.

I have NO gutters and a very steep pitch so I didn't think snow and ice would be very problematic.

Yes, a review of those guidelines would be handy. I'll take some pics. It's difficult to get any that are useful because the roof is so high.

If anyone else has a similar edge, eave or drip vent to recommend that's even more simple, I'd love to hear it.
 
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Old 10-07-15, 06:06 AM
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The calculation is very simplified so they can apply it to many homes. Unfortunately, that means it is not a good fit to all. A steep roof is an example of a poor fit, IMO. They use the attic floor area as a measure of the exposure to moisture transfer, but cathedral ceilings, kneewalls, and other wall area that has conditioned air on one side and attic space on the other need to be considered. Your steep roof probably contains added area that should be added or considered in the following calculation.

Attic floor area divided by 150 provides their total recommended net free area in ft² (NFA) for high and low vents. Multiply that number by 144 to get in². Then use half for the high and half for the low. Note the NFA varies with vent style so check each mfg for their NFA number. A rough average is 50% with the exception being some ridge vents that claim 100%, optimistic.

If you calculate the inside wall and ceiling area exposed to attic spaces you will get a much larger number.

Having vents in high and low positions is the biggest improvement. Getting as close as reasonably possible to the guidelines will then usually be good enough.

Google roof edge vents and there are others.

Bud
 
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Old 10-08-15, 09:29 AM
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On a roof without gutters is one better than the other? That is, an edge vent (that goes about a foot from the edge) VS a drip edge vents?
 
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Old 10-12-15, 09:44 AM
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Anyone? Still trying to decide between edge vents and a drip edge vent so I don't mess up this new roof. These are not popular products up here and it's hard to find local advice.
 
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Old 10-12-15, 10:25 AM
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Hi JR. Probably the reason they are not popular is "snow". The vented drip edge at least positions the vent under the edge a bit to avoid being covered with snow. But it would stioo be subject to an accumulation of ice whic can be reduced but rarely eliminated.

From many years of having to clear off snow and ice, I would probably go with the edge vent all the way down at the edge.

There is another style, but I don't know if it would be applicable. If you have a fascia board then here is a vent built into that location.
http://www.gaf.com/Residential_Roofi...w_Brochure.pdf

Bud
 
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Old 10-12-15, 11:36 AM
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Spoke to the roofer, again, about the two options. His opinion is, because we're not getting ice damn now, not to add any venting to the lower part of the roof. And he's right. But we still have the issue of a non ventilated roof and so get an extremely hot or cold attic.

He says if I insist on either product he'd rather go with the one that's position further from the edge to avoid any ice or water getting into the vents.

And now I am just confused.
 
  #13  
Old 10-12-15, 11:59 AM
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Ventilating an attic is more about removing moisture than reducing the attic temperature. All the calculations are based upon moisture issues. It just happens that in some climates the ice problem pops up and the same ventilation reduces that problem. As for a hot attic in the summer, passive ventilation can never bring the inside attic temperature down to outside temperatures because it is the difference in temperature that creates the air flow, along with a difference in height.

It is insulation that addresses the temperature issues.

He suggests that the vent farther up the roof would be better, but farther up is certain to be covered with snow.

Did you suggest the fascia vent from my last post?

Bud
 
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Old 10-12-15, 12:05 PM
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I did and he doesn't want to do because he doesn't want to cut the decking right at the edge.

I don't need the inside temp of the attic to be the same as outside. I need it to not be 150* when it's 95 outside.

I'm not really concerned about the edge vent and ice dams. Our roof has a really large pitch (being a victorian). I think he just doesn't want to be held liable.
 
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Old 10-12-15, 12:16 PM
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"I think he just doesn't want to be held liable." And that often ends up being the bottom line. If you insist on doing it any other way, he gets to point at you if there is a problem. With a steep pitch and no current ice issues, I would go with his selection.

Bud
 
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Old 10-23-15, 12:59 PM
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So here's an update and I hope someone can weigh in ASAP.

We agreed on an edge vent about a foot up the roof because the "soffits" of the house are decorative and don't actually access the attic.

They finished half the roof yesterday (today off for rain). After they were finished I came home and they had installed the edge vents right at the bottom edge of the roof.

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I talked to the contractor and all he's willing to say is "I told you I didn't want to do it in the first place and they are installed according to manufacturer specs." Even though they obviously aren't venting anything and even though I have more than a few emails wherein we agree that they were to be installed up the roof, he says it's fine and that's that.

So now what the F*** do I do?
 
  #17  
Old 10-23-15, 01:37 PM
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Have you paid them??
Is the person you are talking to a foreman or the owner?
His excuses are lame and defiant.
If he is the owner and refuses to back-up and do the job as agreed then you are probably forced to let him finish. You can't stop him half way through. Then you decide on some course of action, but I can't really tell you what is best. If he won't fix it at no charge, then it is going to be a mess and a lot of people (I'm not one of them) don't want to get into a mess.

Start collecting your paper trail in the event you wish to take legal action. Did you get a certificate of insurance from him so you could talk to his insurance company?

Bud
 
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Old 10-23-15, 01:43 PM
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I HAVE NOT paid them.

He's the salesman and lead for the company. The foreman and the crew are Hispanic.

He and the foreman are coming by tomorrow before they start the 2nd half of the tear off to see what I am talking about as far as the installed vents not accessing the attic. But what I don't understand is, if you JUST tore the entire roof off, isn't it obvious at that point that the overhang doesn't access the attic?

The guy is a friend of my girl's brother so I am hoping we can smooth it over but so far there's no sign of this.

Do I insist he do the other side correctly? Do I insist he fix the vents already installed or just leave them as is? Can they do any harm being there and not venting?

What kind of mess do you mean if he's not willing to fix it at no charge?

Paper trail is collected already. No certificate of insurance though I know they have one - it's a large local company.
 
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Old 10-23-15, 02:03 PM
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If it is a large company, public relations (word of mouth advertising) is important to them. Get to their boss and make your case. The mess is when you have to go to court. But, if it is clear they messed up, the owner will (should) want to make it right.

Bud
 
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Old 10-23-15, 02:51 PM
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Any suggestion if they won't fix it?

OK to leave those vents there and do the other side correct?
 
  #21  
Old 10-23-15, 03:01 PM
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I don't know what is inside those soffits. Some older homes blocked them with a 2x4 and people have drilled holes through that to open up the ventilation. Can you explain how they are blocked and is it possible to open up that path.

Bud
 
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Old 10-23-15, 09:30 PM
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Bud, it looks like that, atop the top plate, there is a 2x4 or 2x6 blocking. Maybe a fire stop? I don't know. But this piece is certainly blocking it along the length the roof.

I suppose it could be opened. I'd have to pull up the attic floor at the base of each rafter bay and drill several large holes but:

a: Is this damaging any structural integrity and
b: Will the holes ever be enough to make the ventilation 'amount' enough? Can the other side (40 feet) of properly installed vents make up for the whole thing?
 
  #23  
Old 10-23-15, 11:52 PM
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It isn't just exchanging the air in the attic, it is, to borrow their term, washing the bottom of the roof with outside air. I have seen many localized problems where a lack of venting in a specific area resulted in mold while the rest of the attic was fine.

It is difficult for me to advise about structure as I cannot see what you see. Pictures might help.

Here are a bunch of pictures, perhaps one is similar.

Bud
https://www.google.com/search?q=soli...iw=931&bih=452
 

Last edited by Bud9051; 10-23-15 at 11:53 PM. Reason: add link
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