Attic Ventilation

Reply

  #1  
Old 07-21-12, 08:49 AM
Z
Forum Topic Moderator
Thread Starter
Join Date: Sep 2005
Location: USA
Posts: 5,539
Received 153 Votes on 136 Posts
Attic Ventilation

I'm looking to improve the ventilation in the attic of a 1960's ranch. The roof is a simple gable with currently very little soffit venting and a single gable vent with fan. There are no particular issues other than heat (no mold, frost, etc), so just trying to be proactive.

The first step will be to add some additional soffit vents at the front and back of the house. Then come the questions.

I am going back and forth between a powered roof vent or 3 or 4 standard roof vents. I'd rather not go with a ridge vent as I'm not sure I can install it myself. I can handle normal vents though.

Once I install the extra soffit vents and some type of top of roof vent, what should happen with the gable vent?

Any other suggestions?

Thanks in advance,
Mike
 
  #2  
Old 07-21-12, 01:53 PM
G
Member
Join Date: Oct 2002
Location: Hamilton County, Ohio
Posts: 4,295
Received 2 Votes on 2 Posts
Just leave the gable vent as is. the closer you can keep the attic to outdoor temperature, the better.
 
  #3  
Old 07-21-12, 04:35 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,965
Received 6 Votes on 6 Posts
Please don't punch holes in a perfectly good roof Ridge vents are too easy, but since you have the gable vent, you have second best. So you're good.
 
  #4  
Old 07-21-12, 07:36 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 36 Votes on 28 Posts
I'll go out on the shaky limb and state that in my opinion passive ventilation is always better than mechanical ventilation as long as you can get sufficient air flow. Not much worse than to have to replace a motor in a hot attic in August to say nothing of the cost for the electricity to run the motor. Solar powered attic fans are a joke as far as I am concerned.
 
  #5  
Old 07-21-12, 09:41 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,469
Received 2 Votes on 2 Posts
The first step will be to add some additional soffit vents at the front and back of the house. Then come the questions.

I am going back and forth between a powered roof vent or 3 or 4 standard roof vents. I'd rather not go with a ridge vent as I'm not sure I can install it myself. I can handle normal vents though.
Make the soffit vent continuous. Add the ridge vent - they're wicked easy and the vent you need. Ditch the fan. Leave the gable vent alone or close it - no big deal either way.

Don't punch holes in a good roof.

Heat in an attic is not a problem. condensation and uneven roof heating in the winter are.
 
  #6  
Old 07-23-12, 01:37 AM
BridgeMan45's Avatar
Member
Join Date: Oct 2011
Location: USA
Posts: 3,194
Received 1 Vote on 1 Post
"Heat in an attic is not a problem." Well, if one isn't concerned with the heat making it hard to keep the house cool in summer, or doesn't care about shortening the life of the roof's shingles, then yes, maybe it isn't a problem.

For the rest of us, using natural ventilation to keep the attic cool is a big plus. I've always been inclined to using wind turbines combined with adequate soffit vents myself, as they do a great job at zero operating expense in removing excessive heat from the attic. I'd swear one could boil eggs from the heat spitting out at each spinning vent on a warm summer day at my place in Albuquerque, NM. Used solid galvanized steel covers to replace them each winter, when it was advantageous to allow some heat to accumulate in the attic. I later helped a buddy install ridge vents on his place in SW Colorado, and he grumbled for months that they weren't very effective in cooling his attic, even though he had lots of soffit vents. His wife didn't want wind turbines because she didn't like the way they looked, even though they could have been hidden from the street.
 
  #7  
Old 07-23-12, 10:42 AM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 36 Votes on 28 Posts
Wind turbines are great IF you have enough wind to cause them to spin, otherwise they are just plain ugly. If they are steel they will eventually rust. When the bearings go they squeak. They WILL move a lot of air provided you have sufficient intake (soffit) vents. Nonetheless they cannot do any more than bring the attic temperature down to the ambient air temperature.

Full ridge venting along with adequate soffit venting will do almost as well as a wind turbine and will do it in absolute dead calm wind conditions if properly installed. You should not use high gable end vents along with a ridge vent system because the air will "short circuit" from the gable vent to the ridge vent.
 
  #8  
Old 07-23-12, 08:53 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,469
Received 2 Votes on 2 Posts
"Heat in an attic is not a problem."
It isn't. As you go on to suggest,
using natural ventilation... is a big plus.
Heat is what drives a well-designed passive ventilation system. And a well-designed passive ventilation system is what will reduce condensation, year-round, and uneven roof heating in the winter. It will also reduce the heat in the attic, both by converting it to mechanical energy to drive the venting, and by venting the warmer air out the exhaust vents.

Well, if one isn't concerned with the heat making it hard to keep the house cool in summer, or doesn't care about shortening the life of the roof's shingles, then yes, maybe it isn't a problem.
Radiant heating through the insulation probably contributes less to raising the temperature inside than heat gain through windows, internal convection, and other non-attic related processes. To the extent that outside heat coming through a sloped wall or a cathedral ceiling is a factor, it may penetrate more through a direct roof-rafter-drywall path than through the insulation in the bays between the rafters. As for shingle life, well, a lack of adequate ventilation can create or exacerbate to problems in every season, can't it.

Turbine vents, turtle vents and similar roof-hole vents are possibly one step better than powered attic exhaust fans, but not by much. As Furd pointed out, they are just plain ugly and they will eventually rust, and fail. In addition, they require punching holes in an otherwise good roof, they are non-continuous, and, most importantly, they are installed below the peak of the roof. That means that the hottest air in the attic will remain there, above those vents, tight up under the ridge.

@Zorfdt: If you want to improve the ventilation in the attic of your 1960's ranch house with a simple gable roof, very little soffit venting and a single gable vent with fan , and do it in the most effective manner you can, then make the soffit vent continuous. Add the ridge vent - they're wicked easy to install and the exact exhaust vent you need. Ditch the fan. Leave the gable vent alone or close it. Furd gave the standard argument for closing it off, but I think the evidence is that it's really no big deal either way.

And as Larry said,
Please don't punch holes in a perfectly good roof
 
  #9  
Old 07-25-12, 12:27 PM
BridgeMan45's Avatar
Member
Join Date: Oct 2011
Location: USA
Posts: 3,194
Received 1 Vote on 1 Post
Doesn't installing a ridge vent require cutting a slot or hole in a perfectly good roof?
 
  #10  
Old 07-25-12, 01:07 PM
S
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 19,605
Received 97 Votes on 85 Posts
It does but the benefit of this cut outweighs the risk.
 
  #11  
Old 07-25-12, 02:08 PM
BridgeMan45's Avatar
Member
Join Date: Oct 2011
Location: USA
Posts: 3,194
Received 1 Vote on 1 Post
I think an important point is the fact that some ridge vent brands/designs are considerably better than others. The type with a dense, black plastic woven-type foam doesn't allow much air movement through it at all--I helped a neighbor install one on his house (he chose it and bought it before asking for my help), and on a cool but sunny day when the attic was roasting, you couldn't feel hardly any warm air moving through it out of the attic. By contrast, on that same day, I took the neighbor up on my roof to show him how much hot attic air was rushing out of my trusty wind turbines. The words he uttered can't be printed here.

And regarding corrosion possibilities mentioned by some posters--most turbines these days are made of aluminum, so rusting is not a problem. Just a few drops of light oil in the bearing assembly once a year is all the maintenance they ever need.
 
  #12  
Old 07-25-12, 02:34 PM
S
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 19,605
Received 97 Votes on 85 Posts
Maybe but there's a lot more surface area to the ridge vent than the turbines with the number I've ever seen on a roof so the air would not need to move as fast through the ridge vent to move the same cfm.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: