# Ranch Style Home Attic Ventilation



## Windows on Wash (Aug 30, 2011)

You are correct.

Skip the power vents and put on enough roof louvers to balance out the system.

In the scheme of ventilation nightmares...yours is an easy fix.


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## shazapple (Jun 30, 2011)

I would keep the ridge vent as well as add the 4 roof louvres. No worries about pitch. 3/12 or 4/12 is fairly standard.


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## ulrichfolkers (Mar 22, 2012)

I'm all for leaving the ridge vent. Less work for me. But, do you think it's possible that by leaving the ridge vent and adding louvers, that the 2 system(s) of vents would work against one another? Namely, the ridge vent drawing outside air in from the louvers instead of expelling hot air from the attic. Or vice versa? I've read references about this type of condition being created due to mixing exhaust vent types together, so, I thought I'd throw it out for discussion. Maybe I should just implement your suggestion and don't over think this. Adding the louvers has got to improve this situation.


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## AndyGump (Sep 26, 2010)

What are the venting issues you are experiencing?

Are you getting condensation in the attic area?
If so, perhaps the soffit venting is being blocked by insulation?

If you are not experiencing any real issues than why do anything to the roof that you do not need to?

Others may disagree with me but I think it is much better to have more soffit venting area than ridge vent area.

By the way, don't worry about snow building up around your ridge vent, ( I know you didn't say anything about this) snow is not an air barrier.

Andy.


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## ulrichfolkers (Mar 22, 2012)

I bought this house in November of last year, so, I haven't had the benefit of at least a full year's experience with it. I haven't noticed any condensation thus far. The 2 things I noticed were:

1. When I was in the attic in the spring doing some electrical work, I thought it seemed unusually warm (in the attic) given that it wasn't even summer yet.

2. We just had a heat wave, 3 days above 90 and humid. It seemed to me the house heated up quite fast and stayed that way. My previous experience with houses was owning a colonial style house with a steep pitched roof and adequate attic ventilation. When I owned the colonial, I remember it took several days of hot & humid weather before the ambient tempurature in the house actually got hot. In comparing the colonial to the ranch, the ranch seemed to heat up and hold the heat right away. I came to the conclusion that attic venting may be at issue. That coupled with applying industry standards regarding attic venting, I came to the ultimate conclusion that the exhaust venting in the attic is insufficient. The attic is just plain heating up and holding too much heat.


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## AndyGump (Sep 26, 2010)

I thought that that might be the case.

The attic venting is really not designed to "cool" the attic, it is there mostly for removing moisture from the attic.

You would probably find that you need more insulation in the attic and that would go a lot farther to satisfying the heat issues in your house.

Now the International Residential Code requires attic venting area that is 1/150th of the total attic area. If you have 1000 sq. ft. of attic space then you need 1000/150= 6.66 sq, ft, of venting area.
1/2 of which is at the eaves (or soffits) and the other is located not less than 3 ft. above the eave line, (gable vents, roof vents ridge vents).

Personally I think that having 1/2 the area on the ridge is too much as it may cause conditioned air to be drawn from the house.

You would be better off with more insulation and sealing the wall/ceiling areas from the attic area.

Andy.


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## ulrichfolkers (Mar 22, 2012)

You make some good points here. Do you think though that maybe my intake/exhaust venting is out of balance? I only have about 8 linear feet of ridge vent as exhaust venting, but there's soffit venting on all 4 sides of the house, this being a hip style roof. So there's much more intake than exhaust here.


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## AndyGump (Sep 26, 2010)

What is the actual venting area of the ridge vent?

if it is about 3" on both sides of vent then you are good.

It would be better to have more soffit vent area than ridge vent area (in my opinion).

Andy.

Andy.


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## ulrichfolkers (Mar 22, 2012)

When I was in the attic in the spring, I remember looking up at the ridge briefly. Though I didn't measure it, it looked like there was about 1-1 1/2 inches of gap opening on either side of the ridge line. So the total may be a 2 - 3 inch gap in the roof decking. I hope I'm answering your question.


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## Windows on Wash (Aug 30, 2011)

AndyGump said:


> What are the venting issues you are experiencing?
> 
> Are you getting condensation in the attic area?
> If so, perhaps the soffit venting is being blocked by insulation?
> ...


I agree with you wholeheartedly here. I like to see a 60/40 split usually and you are spot on with the other observations and recommendations.


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## ulrichfolkers (Mar 22, 2012)

I checked to make sure the soffit vents were not blocked. So, other than the attic being what I would call hotter than it should be, I don't see evidence of detrimental issues. From what I know about attic ventilation, if the goal is to and have the attic temperature as close to the outside air temperature as possible, then adding some louver venting certainly couldn't hurt.

If I elect to "do nothing", then the only 2 issues (if one could call them issues) are:

The house holds more heat during the summer due to higher attic temperature, and I may not get as long a life out of the roof shingles.

Where I can do all of this work myself, (and it keeps me out of trouble), I figured the only thing I could do is "improve" the situation some by adding louver vents.

I like "kicking this around" with you guys, it's fun! But, here's the bottom line: "I would never want to ignore sound advice".


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## AndyGump (Sep 26, 2010)

Then my suggestion is that you add more insulation rather than mess around with the venting.

Your attic can not get hot enough to destroy the shingles.

Andy.


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## shazapple (Jun 30, 2011)

ulrichfolkers said:


> I'm all for leaving the ridge vent. Less work for me. But, do you think it's possible that by leaving the ridge vent and adding louvers, that the 2 system(s) of vents would work against one another? Namely, the ridge vent drawing outside air in from the louvers instead of expelling hot air from the attic. Or vice versa? I've read references about this type of condition being created due to mixing exhaust vent types together, so, I thought I'd throw it out for discussion. Maybe I should just implement your suggestion and don't over think this. Adding the louvers has got to improve this situation.


Where they will be at a similar level I don't think it will be a problem. Adding insulation is a good idea (although depends how much you already have). It is fairly cheap and you might as well do it while you are up there!

I find a lot of roofers use the 'cobra' ridge vents which lose effectiveness because nails are overdriven and compress the vent material.


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## CopperClad (Jun 22, 2012)

I'm going to have to disagree. I'm not a designer or anything.. but.. In the old days there was no such thing as ridge vent. Roofs would last 15 years if your lucky.. Ridge "vent" is to let the "hot" air vent. Heat rises to my knowledge. If it doesn't have anywhere to go? Attic gets hot, which in turn does wear on your shingles?? Look at the pics, your due for a reroof shortly, and with older shingles in itself is having a small effect. They even have energy star rated shingles now! Just my opinion though, let your roof breath. But yes, added insulation for sure sounds like a good idea as well. Good luck!


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## ulrichfolkers (Mar 22, 2012)

Good points made by all....

There is loose insulation the depth being just over the top of the 2x6 joists. So maybe 6 or 7 inches of loose insulation is there. Because of the shallowness of the roof the original builder didn't bother putting any flooring in the attic. So I ripped a couple of 4x8 sheets of plywood to put up there for flooring so I can walk around. Do you suggest adding several more inches of loose insulation? I certainly can do that. Maybe add the insulation and install some louvers and call it good??


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## CopperClad (Jun 22, 2012)

With 6'' of insulation I believe is R-19. Most home built nowadays depending on your area need at least R-38. Pump it in !


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## AndyGump (Sep 26, 2010)

Pump it in or use batts, just make sure you leave space for venting.

Andy.


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## ulrichfolkers (Mar 22, 2012)

Sounds like I have an agenda.....

Thanks much...


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## Windows on Wash (Aug 30, 2011)

CopperClad said:


> I'm going to have to disagree. I'm not a designer or anything.. but.. In the old days there was no such thing as ridge vent. Roofs would last 15 years if your lucky.. Ridge "vent" is to let the "hot" air vent. Heat rises to my knowledge. If it doesn't have anywhere to go? Attic gets hot, which in turn does wear on your shingles?? Look at the pics, your due for a reroof shortly, and with older shingles in itself is having a small effect. They even have energy star rated shingles now! Just my opinion though, let your roof breath. But yes, added insulation for sure sounds like a good idea as well. Good luck!


Shingle heat being touted as a destructive force is overused and largely promoted by the shingle manufacturers.

The difference in shingle surface temperatures between a sealed and completely vented attic are extremely slight (usually less than 2 degrees and this is in FL and Vegas). The differences will be even less in Northern climates or areas with shading.

+95% of the cooling happens via convection to outside and not through the plywood and into the attic.

Venting issues create moisture issues and those moisture issues can ruin a shingle...not the heat.


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## CopperClad (Jun 22, 2012)

If the homeowner had a gable roof the venting wouldn't be issue. However the OP has a hip roof. When you say a 60/40 split, I think what you are saying is 60 intake, 40 exhaust ? In the OP's case, lets just say his home is a 50'x50' box. That means he has 200' of intake, and 8' of exhaust ... Just doesn't seem right at all to me. Again, that is just my opinion. If it were my home, I would be sure to add more outlet venting.


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## ulrichfolkers (Mar 22, 2012)

Copperclad
I agree with you, and agree about adding more insulation. So, to reiterate, I'm going to add additional attic insulation and add louver vents.

Windows on Wash
Thanks for your input regarding moisture and heat issues with respect to roof shingles.

And Thanks again to all....


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## Windows on Wash (Aug 30, 2011)

CopperClad said:


> If the homeowner had a gable roof the venting wouldn't be issue. However the OP has a hip roof. When you say a 60/40 split, I think what you are saying is 60 intake, 40 exhaust ? In the OP's case, lets just say his home is a 50'x50' box. That means he has 200' of intake, and 8' of exhaust ... Just doesn't seem right at all to me. Again, that is just my opinion. If it were my home, I would be sure to add more outlet venting.


60/40 as a ratio is a good target number. Most roofs (especially today) will be heavy on the exhaust and lack on the intake. This is as a result of short cuts on the soffits, obstructed soffits or complex roof lines and poor intake.

Too much exhaust and not enough intake drives stack pressures and drive air exfiltration and moisture migration to the attic (exactly what we don't want to happen).

In the original posters question, he does need more exhaust to balance out the system without question. That needs to be addressed for certain.

Insulation is part of the equation. Air sealing is the other part of it. 

Stop the air movement and you really put the brakes on the moisture movement.


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## shazapple (Jun 30, 2011)

Windows on Wash said:


> Shingle heat being touted as a destructive force is overused and largely promoted by the shingle manufacturers.
> 
> The difference in shingle surface temperatures between a sealed and completely vented attic are extremely slight (usually less than 2 degrees and this is in FL and Vegas). The differences will be even less in Northern climates or areas with shading.


I see this number touted a lot, but that is an average temperature over the entire day, so it's not really a fair comparison. Also it is misleading as people assume it is relative to the exterior temperature. The peak temperature of a sealed attic is about 10 degrees F higher than the vented attic, which is already at 150 degrees F.


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## Windows on Wash (Aug 30, 2011)

shazapple said:


> I see this number touted a lot, but that is an average temperature over the entire day, so it's not really a fair comparison. Also it is misleading as people assume it is relative to the exterior temperature. The peak temperature of a sealed attic is about 10 degrees F higher than the vented attic, which is already at 150 degrees F.


Shazapple,

You are correct. I probably should have explained my remarks a bit better as I was speaking to the average peak shingle temperature differences on several measure sides of a roof. I also should have done a better job of stating whether I was referring to Celsius or Fahrenheit but most of the papers switch between the two.

If you look at a roof surface peaks, they were under the most severe of conditions and orientations and the average peak differences probably fall in the 4-7 degree range 95% of the time with the remaining 5% reaching the 8 degree peak temperature differential.

Here are a couple of quote from from BSC study papers:

*BSC Research Report 9701* - _Peak summer day simulations for Las Vegas showed that the temperature of black roof shingles did not vary by more than 8 degrees F, whether the attics were sealed or vented_. _The maximum predicted black roof shingle temperature for the sealed “cathedralized” attic was 204 degrees F._

_The maximum measured plywood roof sheathing temperature increase of 17 degrees F for the sealed attics is less than the temperature variation experienced by changing from tile to asphalt shingles of any available color. The maximum measured plywood sheathing temperature of 
126 degrees F, for the sealed attics during the test period, is well within an acceptable temperature performance range (less than 180 degrees F) of wood-based roof sheathing._

Color, orientation, and pitch have much more to do with how warm a shingle is as compared to sealed or vented attic.

Example, a black shingle on a low pitch and well vented roof will have a much higher surface temperature than a lighter color shingle on a more aggressively pitched roof. A vast majority of the cooling happens to outside and the effectiveness of convection is about pitch and not if the deck is sealed. 

If shingle manufacturers were really concerned about surface temperatures, they should start mandating that you can't have a darker shingle on a more shallow roof seeing as that will have much more to do with the peak temperatures that it will reach. After that, they should tell folks South of the Mason Dixon line that they only get the lighter colors. 

Until they start doing that, I don't think the shingle temperature argument holds much weight from them.


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## Gary in WA (Mar 11, 2009)

ulrichfolkers; Do me a favor and go in your attic. Look for all the soffit air holes punched there, you should be able to see them all (if daylight hours....). Or are they sporadic?

Gary


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## ulrichfolkers (Mar 22, 2012)

GBR,

I remember checking the soffits to make sure that they weren't blocked. I did see daylight consistently. The ridge vent is the "steel wool" type material. Maybe the vent is clogged or compressed too tightly when the cap shingles were nailed?? Interestingly, I found an old post that had your DNA on it in which "ridge vent clogging was spoken about":

http://www.diychatroom.com/f9/ridge-vents-81583/

I would have no problem replacing the existing ridge vent with say the Shingle Vent II or Cobra or something comparable (perhaps I should do this anyway being it's only 8 feet). But, I just can't seem to get past the fact that there's only about 8 linear feet of ridge venting in my hip roof, and, when you compare that to A frame roofs, A frames can have 30 or more linear feet of ridge venting. That's quite a bit of a difference. That's why I was giving serious consideration to adding some louver vents.

I hope what I'm proposing to do will improve the situation even if it's only a slight improvement. That being said I really value input from this group. I want to "go to school" here from the knowledge graciously shared here by the group.


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## Gary in WA (Mar 11, 2009)

I think Andy mentioned the Code with 3' rise space between the intakes and exhaust and 50-80% more exhaust with the 1/300, otherwise you need 1/150 (with 40/60); http://publicecodes.citation.com/icod/irc/2003/icod_irc_2003_8_sec006_par001.htm

Install some "turtle-backs" (static box vents) for more exhaust, to balance the ratio. Remember when figuring your NFVA of the soffits, the 1 in 3 vinyls are only 1.56 NFVA per ft., and the full perforated vinyls (3-4") are only 4.68 NFVA per foot- so you need 2' deep soffits (times both sides of house) with full perfs (every one) to match a new ridge vent with baffles at 18 per foot. Change out the mesh for a: http://www.buildsite.com/pdf/airven...w-Performance-Tests-Technical-Notes-20924.pdf

Quite the difference: http://www.youtube.com/watch?v=rE6fyWHfTXc

Gary


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## ulrichfolkers (Mar 22, 2012)

Gary,

Man....This stuff is a "Science" all of its own. The Youtube video was very enlightening. I'm definitely going to replace my ridge vent with Shingle Vent II, along with adding some turtle vents.

I sure have learned a lot here. Anybody else want to "Vent" here? I couldn't resist. My wife tells me I'm a Wise-a**, But humor keeps me sane!

Steve


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