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ulrichfolkers 06-25-2012 09:06 AM

Ranch Style Home Attic Ventilation
 
2 Attachment(s)
Hi Folks,

I'd like to address an attic ventilation issue I have, and I'd like to get input from the group. I have a small ranch style home (900 sq ft.) with a hip roof (I've attached some pics). I'm located in Massachusetts. There is continuous soffit venting thru out, but my concern lies with the exhaust venting, or lack there of. As you can see from the pics, there is only a small ridge vent (8 feet maybe). I haven't been up there to measure. IMHO this is way under (exhaust) vented. Here's my thoughts so far:

Add more ridge venting. Not sure about this option because of the roof pitch. I'll have to get up there and measure to see if it's 3/12 or 4/12.

Power vent. I haven't heard too many good things about power vents.

Roof Louvers. Something like the Master Flow SSB960A (http://www.gaf.com/roofing/residenti...f-louvers.aspx#).

I'm thinking that roof louvers is the way to go here? The Master Flow site recommends 4 louver vents for attics up to 1000 sq. ft. So, would my best bet be to remove the ridge vent, and add 4 louver vents? Also, can the roof louver vent be used on a low pitched roof such as mine? The Master Flow doesn't appear to address this.

Thoughts anyone?

Thanks

Windows on Wash 06-25-2012 09:30 AM

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.

shazapple 06-25-2012 09:54 AM

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.

ulrichfolkers 06-25-2012 10:32 AM

Ranch Style Home Attic Ventilation
 
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.

AndyGump 06-25-2012 11:00 AM

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.

ulrichfolkers 06-25-2012 12:25 PM

Ranch Style Home Attic Ventilation
 
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.

AndyGump 06-25-2012 12:40 PM

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.

ulrichfolkers 06-25-2012 12:54 PM

Ranch Style Home Attic Ventilation
 
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.

AndyGump 06-25-2012 01:10 PM

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.

ulrichfolkers 06-25-2012 01:36 PM

Ranch Style Home Attic Ventilation
 
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.

Windows on Wash 06-26-2012 06:31 AM

Quote:

Originally Posted by AndyGump (Post 951194)
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.

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.

ulrichfolkers 06-26-2012 08:23 AM

Ranch Style Home Attic Ventilation
 
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".

AndyGump 06-26-2012 09:11 AM

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.

shazapple 06-26-2012 09:28 AM

Quote:

Originally Posted by ulrichfolkers (Post 951157)
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.

CopperClad 06-26-2012 09:41 AM

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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