Gables: Close or Keep Open


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Old 12-14-14, 06:06 PM
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Gables: Close or Keep Open

I have a 1950s-era split level house with 2-inch soffit vents, ridge vents AND gable vents.

The previous owners closed up the gable vents and the attic baked. I opened them up and saw some improvement. But I also discovered that part of the problem was all the soffit vents were covered with insulation. I'm thinking maybe the original house only had gables and when they got a new roof they added a ridge vent and soffits? When did ridge vents become popular?

Anyway assuming I can pull the insulation that is blocking the vents using baffles, do I close the gables? I'm planning on getting a lot of blown in cellulose added to the attic shortly so I need to decide shortly what I'm doing; once that stuff is in there, it's going to be a PITA to work around.
 
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Old 12-14-14, 06:10 PM
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I should note the roof line is T-shaped with a gable at all three ends.

Also, the one side of the T is a cape-cod style story with not perfect ventilation from the knee wall attic to the top attic. The ceiling joists are partially full of insulation. Do I keep the gable open on this side, but close on the other?
 
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Old 12-14-14, 07:00 PM
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The old advice was to close those gables to prevent air flow from gable to ridge "short circuiting" the desired path from soffit to ridge. In reality, leaving them open simply improves all air flow. The only caution would be if those gables present a wind driven snow or rain problem with the improved air flow, but in most cases that issue would have already been noticed.

As for the "T" that is a cape style, does this result in what I term a as "mid-level" vent? Most homes will deal with just high (exhaust) and low (intake) vents, but when mid-level vents of any type are introduced it becomes more difficult to identify whether they will be acting as intake or exhaust vents. Are yours all high and low or do you end up with some in the middle? Otherwise, leave the cape gable vents open.

Note, before that new insulation is added be sure to air seal those ceilings as much as possible.

Bud
 
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Old 12-15-14, 09:04 AM
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Not sure exactly what you mean. I think the roof lines are pretty even. It's possible one is up to a half a story higher.

As for the actual gable vent placement, they are located in the same distance from the peak of the room on all three corners. I'd say no more than two or three feet.
 
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Old 12-15-14, 09:45 AM
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It is a difficult concept and at this point little you can change, as for now you don't know if it is a problem or not.

Here's a short article on roof venting.

Bud
 
 

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