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What's the easiest and cheapest way to seal off an attic fan?

What's the easiest and cheapest way to seal off an attic fan?


  #1  
Old 03-22-18, 05:05 PM
M
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What's the easiest and cheapest way to seal off an attic fan?

The previous owners did a lot of electrical *work* on the place and once of the messes is a 38"x38" fan in the attic between the carport and attic wall.
The attic floor is insulated but when I stand next to that fan it's cold as a witch.
By the way the fan's not running, never has, no power to it and the attic has those triangular vents at the top on both sides.
The box that it sits in measures 38"x38", I initially thought about using insulation board but now I'm thinking why bother.
So what's the cheapest easiest way to cut off the cold air from coming in from the carport via the fan's entryway?
The cheapest would probably be that window saran wrap stuff but that's a PITA to put on and the glue strips never stick good.
 
  #2  
Old 03-22-18, 07:24 PM
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So your garage is cold? Your house is insulated so it should have no effect on your living space. The fan most likely was designed to remove heat from the garage in the hottest part of the summer. Not sure where you are in VA, but where I am (south east coastal) it gets bloody hot around here in the summer. Hi 90's with 100% humidity. Some older homes had the space above the garage open to the attic in ranch style homes. I'm sure the fan was to take care of that problem. Are you sure there is not power to the fan? May be a thermostatic controlled unit instead of a switch type fan.
 
  #3  
Old 03-22-18, 07:48 PM
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Trying to figure out exactly what's going on.
Got a picture so we can see how this carport ties into the attic?
Do not need a picture of the inside of the attic, no close ups, just a picture of the outside.
I agree the attic ideally should be the same temp. as the outside temp.
Any garage or carport should be separated from the attic space with 5/8" fire rock to meet code.
 
  #4  
Old 03-23-18, 05:19 AM
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I agree a photo or two would be very helpful. In terms of easiest, you should be able to seal it from above then build a cover (box) over the fan made of XPS. A slightly more difficult approach could be removing the fan then adding insulation and sheetrock. But without pictures it's difficult to do more than guess.
 
  #5  
Old 03-23-18, 05:24 AM
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Oops, I thought I'd posted a picture.
This is taken from within the attic so on the other side of the bricks is the carport roof.
 
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  #6  
Old 03-23-18, 06:02 AM
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There is no wall there, just a fan so what difference will it make if you cover just the fan?

You have insulation on the floor of the attic (above the living space) so there is no benefit to adding any insulation to the fan or the area around where the fan currently sits!
 
  #7  
Old 03-23-18, 06:10 AM
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It's hard to evaluate but everything is closed with the exception of:
a) the fan hole itself
b) the triangular area above the fan (usually open in most if not all attics I've seen)
c) the crumbling mortar areas within the bricks on the upper area of the fan.

the areas of b and c combined are minimal compared to the gaping 38"x38" of the fan hole (a)
 
  #8  
Old 03-23-18, 11:59 AM
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Duh!

Was getting to old to crawl into upper attic area where fan was located.

To block off a fan in difficult to access attic area I use a plywood panel hinged across top of fan opening.

From an easily accessed area of attic have a cord attached to bottom of panel. Gravity keeps it closed. Spring and fall use cord to open or close panel. On/off switch and thermostat in same place.

Permanently closed of triangular vent. Installed new intake vents in accessible area. Block them in winter.

Rule of thumb for attic ventilation: Inlet air net area (not measured) area/size should be twice fan area.
 

Last edited by doughess; 03-23-18 at 01:18 PM.
 

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