# Under Shingle Vents



## Yodaman (Mar 9, 2015)

I am doing a asphalt shingle roof tear-off and re-roof within a couple weeks. House is a plain cape style with no overhangs. Roof pitch is about 9/12. 

Having no overhangs, these capes in the neighborhood are notorious for ice dam leaks so I am planning to use a shingle vent, off edge for some intake ventilation.

My preferred dealer is stocking Lamanco, http://www.lomanco.com/index.php/vents/specialty-vents/deck-air.
I am a little concerned about the vent openings facing up being covered with snow easily. 

Ceratainteed has one where the vent openings are directly under the shingle, https://www.certainteed.com/residential-roofing/products/certainteed-intake-vent/.

Has anyone used either in snow country? Or possibly another MGF?
Not interested in anything that comes in roll.


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## Bud9051 (Nov 11, 2015)

Same pitch cape and have been working to reduce/eliminate the ice dams. Making good progress but it hasn't been easy.

IMO, low shingle vents or edge vents will be vulnerable to ice dams which as you probably know can show up even with the best roof/insulating installs. Back to shingle vents in a minute.

My roof has/had 12" soffits so not as challenged as yours, but I added 4" to my siding for exterior foam insulation and didn't want to reduce my soffit size, so I extended most of my rafters to get back to 12" and 18" on my dust pan in back. A lot of work and best if combined with a new roof. How complicated yours would be I can't say. I did not extend the gable ends which are now 8" but no ice problems there.

I did uncover a couple of design issues with my cape that were contributing heavily to my ice issues. If you have pictures I can see if yours might be similar.

Shingle vents can be good, but they are only part of eliminating the ice problems and if there are still ice dams those vents are a hole waiting to be a disaster.

Bud


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## Yodaman (Mar 9, 2015)

Thanks Bud, I agree, cutting a 1" slot near the bottom of the roof seems counter productive, but if it keep the air temps behind the knee walls closer to outside temps then ice dams should be eliminated, in theory! Planning to put in R40 on the floor behind the knee walls. R19 up the wall. Baffles under the short cathedral and then R40 again at the ceiling.

The house was built around 1950 and has never had any soffit vents. During the last roof install someone did install a ridge vent. (rolled type, probably 12 NFVA). I am planning to replace with a rigid type with 18 NFVA.

I agree that building overhangs and soffits would be the most ideal, but this being rental property is not really a option.

My local codes do require 24" of ice and water. Measured horizontally from the outside wall.

I was planning to install the vent after the 3rd shingle course. That should be far enough away from the gutter. Climate zone 4/5,


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## Nealtw (Jun 22, 2017)

The idea of venting is to get cool air over that outer wall.


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## Bud9051 (Nov 11, 2015)

LOL, upstate NY must be everything north of NYC.
Man they didn't waste any lumber on rafter tails on that one.
Good air sealing, a block directly below the kneewall, and as much insulation as possible over the outside top plate is going to be the best you can do without a major rebuild. I've watched a few now homes obviously built with at least code minimums and they have shown zero sign of ice issues. What you are proposing should be as good if the edge vents don't get buried with snow. Being a rental will you or they be watching for excess snow and/or ice?

Bud


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## Windows on Wash (Aug 30, 2011)

There are a handful of products out there that can accomplish this. I think that DCI was one of the first. We have used the DCI and OC products with success and good feedback.


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## Yodaman (Mar 9, 2015)

Bud9051 said:


> LOL, upstate NY must be everything north of NYC.
> Man they didn't waste any lumber on rafter tails on that one.
> Good air sealing, a block directly below the kneewall, and as much insulation as possible over the outside top plate is going to be the best you can do without a major rebuild. I've watched a few now homes obviously built with at least code minimums and they have shown zero sign of ice issues. What you are proposing should be as good if the edge vents don't get buried with snow. Being a rental will you or they be watching for excess snow and/or ice?
> 
> Bud



I think anything outside of NYC qualifies as upstate. We are worlds apart in almost every way.

Regarding the house, they were put up fast during the 40's and 50's as temp housing to support the war effort. Seventy years later they have held up pretty well. Some seniors still living in them, but mostly starter homes and rentals now.

As for the intake vents, putting them on the edge makes me a little nervous. Having a gutter directly under it just seems like asking for trouble in the winter months. So I am leaning toward "off edge" about 16". Three full shingle courses then the vent.

Planning to do some air sealing, as for the blocking under the knee wall, I will probably just wad some fiberglass in a garbage bag and seal the cavity.


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## Nealtw (Jun 22, 2017)

That's great, when you get ice dams you will have open vent for water to go in.
Drip edge vents and gutters play well together.


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## Bud9051 (Nov 11, 2015)

Have you looked at these? Edge vents that extend a bit and might reduce the risk of water getting back in.
http://buymbs.com/p-483-air-vent-ve...MI_8i2hsXy1QIVAwRpCh09SwsXEAYYASABEgJg4vD_BwE

They also used to have a vented fascia board but I couldn't find any. GAF says discontinued but there should be others.

Bud


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## Yodaman (Mar 9, 2015)

Nealtw said:


> That's great, when you get ice dams you will have open vent for water to go in.
> Drip edge vents and gutters play well together.



So, no trouble with ice and snow building up on the gutters and blocking the vents? That is my main concern with a vent on the edge.


Anther small detail I missed. On the back side of the roof, it transitions onto a shed roof. The roof covers a unheated, but enclosed porch. 
In this scenario I would need to be a few courses above the valley.

I was looking again at the Certainteed, (also stocked local), but from what I can see installation is at the edge only. No one local has the DCI on the shelf.

Think I am back to the Lomanco.

Also planning to bend up 5x3 gutter apron in lieu of drip edge on the eve ends.


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## Nealtw (Jun 22, 2017)

Yes snow will be a problem but not much you can do about that, maybe have the gutter below where the snow will slide over
The problem you have with all of that is you want the vents in the same place as you want it sealed.


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## Yodaman (Mar 9, 2015)

Nealtw said:


> Yes snow will be a problem but not much you can do about that, maybe have the gutter below where the snow will slide over
> The problem you have with all of that is you want the vents in the same place as you want it sealed.



kind of the reason I think a few courses up is a better option,


Monday morning I plan to grab a permit, hoping the building inspector will be around, maybe he can at least tell me what others are using around here.


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## Yodaman (Mar 9, 2015)

The building inspector was of little help. So I went with the Lomanco, which can install on edge or off. I did the back side first and put the vent two courses above the valley.

For anyone looking at pros and cons of on edge vs off edge, the off edge install is a little more expensive. It requires another shingle starter course (roll) over the vent.


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## Yodaman (Mar 9, 2015)

Just finished shingling the front side of the house. Snapped a few pics along the way.

Tear off was a breeze. Notice the nail placement is too high missing the tops of the course underneath. So effectively getting half as many nails in each shingle








Their ice water was placed on top of a layer of tar paper, again wrong but simple to tear off








2 1/2 x 5 1/2 gutter apron, first course of ice and water








Starter strip. First used this roll product a couple years ago, great product








vent going down








another ice and water over the vent, followed by another starter strip, then ready to shingle. My nail placement is a little low to miss the 1" vent slot underneath


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## Yodaman (Mar 9, 2015)

a few rows after the vent is down


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## Marky82 (Dec 17, 2015)

I have the same type of house. No eaves but I do have a ridge vent. Current roof is about 8 years old so it has a lot life left. When I get around to adding lower venting I was going to try a product like FaciaVent (other companies have similar products). I'll take off the gutters, cut an opening at the top of the exterior wall where it meets the roof, install the FaciaVent then a facia board, and reinstall the gutter. This method seems to be less prone to water intrusion if an ice damn did form. It's also easier to retrofit without reroofing (the biggest reason why I like it). 

Nice job installing the Lamanco! Keep us updated on how the roof looks a few days after a snow storm.


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## Yodaman (Mar 9, 2015)

Marky82 said:


> I have the same type of house. No eaves but I do have a ridge vent. Current roof is about 8 years old so it has a lot life left. When I get around to adding lower venting I was going to try a product like FaciaVent (other companies have similar products). I'll take off the gutters, cut an opening at the top of the exterior wall where it meets the roof, install the FaciaVent then a facia board, and reinstall the gutter. This method seems to be less prone to water intrusion if an ice damn did form. It's also easier to retrofit without reroofing (the biggest reason why I like it).
> 
> Nice job installing the Lamanco! Keep us updated on how the roof looks a few days after a snow storm.




I like the looks of the FaciaVent. If I have performance issues with this set up I would consider it. I looked at some other options at the eves, but don't recall any that vented from under the fascia. They all seemed to vent at the drip edge or above the roof and gutter which concerned me.


When you are ready to install yours, check inventory from your supplier. My local DCI supplier had zero inventory on hand of their SmartVent.

Regarding snow piling up, this roof 10/12 pitch which should at least help.


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## Yodaman (Mar 9, 2015)

Performance update on this shingle vent application:
We rec'd 4 to 5 inches of snow the other day, so I was able to see 
how the the snow was melting. These small capes are notorious for ice building 
up at the eves causing ice dams and roof leaks. 
This is what I see,







Even though the lower vent is mostly still covered by snow enough air is getting in to keep the crawl space cool. No ice at the eves. 







Around back where the lower vent is above the valley, same, no problems with ice build up, snow mostly covering the roof.







A shot of the neighbors roof, all most all snow has melted off







Other neighbor, most of snow has melted, ice building at the eves. This house even has a soffit, but has triple 5 metal center vent in it. Very low NFVA (maybe 3)

So over all, so far I am happy with the results of lower shingle vent.


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## MI-Roger (Aug 8, 2009)

Might be a vent solution on the back side of my two story home with 4/12 pitch and no eaves in the back. The front edge of the roof has eave overhangs of a foot or more, go figure.

Anyway, the Lomanco literature/photo/illustration posted in the first message made it appear there were transition pieces for use at the vent ends when installed under shingles part way up the roof. Are these pieces available or is the image somehow distorted?


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## Yodaman (Mar 9, 2015)

MI-Roger said:


> Anyway, the Lomanco literature/photo/illustration posted in the first message made it appear there were transition pieces for use at the vent ends when installed under shingles part way up the roof. Are these pieces available or is the image somehow distorted?




You are referring to the off roof edge install. No additional parts needed.
They instruct you to cut out a pie section of the vent which allows you to turn the end down 90 degrees. This caps your end and give you the tapered transition.
I didn't use this method since was there will essentially be no ventilation to the two outside rafter bays. 

I ran the vent edge to edge.


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