bathroom ceiling insulation - minor replacement

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  #1  
Old 07-20-14, 07:34 AM
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bathroom ceiling insulation - minor replacement

I replaced a bathroom exhaust fan.

In between the joists where the fan was installed, there was about 3' of insulation that looked in real bad shape. It was 2 layers of a thin insulation with a foil backing. The foil backing was was on top (not touching the drywall back). The foil just flaked away from age.

Anyway, I replaced it with R25 unfaced roll for that 3' span and around the new fan.

Is the lack of a paper backing or plastic/vapor barrier under it a recipe for damage?
 
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  #2  
Old 07-20-14, 07:50 AM
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Vapor barrier

Unfaced insulation the kind you used, is correct, no vapor barrier should be used in the ceiling, the moisture that passes through the ceiling drywall, if it were to hit a vapor barrier, would turn to water and cause mold to form
 
  #3  
Old 07-20-14, 08:17 AM
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Does the ceiling with the fan butt up to a cold attic or is this the first floor of a 2 story?

Bud
 
  #4  
Old 07-20-14, 08:59 AM
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It butts up against the attic.

Thx both for your replies.
 
  #5  
Old 07-20-14, 09:25 AM
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Up against a cold attic means (being a bathroom) you would probably want a vapor barrier next to the drywall (warm side). But being just a small area with little or no effective VB in the rest of the ceiling it probably does not matter. The more important aspect of moisture in a bathroom would be to put that new fan on a delayed on/off switch. Not expensive and can be set to allow the fan to continue to run for 20 minutes or so to be sure the moisture from a shower has been exhausted.

Next is, where does that fan exhaust to and I assume you will be improving that attic insulation.

Bud
 
  #6  
Old 07-20-14, 11:39 AM
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Next is, where does that fan exhaust to and I assume you will be improving that attic insulation.
I wasn't planning on replacing or improving any more unless there is an issue. The insulation is likely 60 years old and it has newer blown in insulation on top of it that appears to be new within the past 10 years.

As for where it vents too, unfortunetly it doesn't have an attached vent cut into the roof. It is attached directly under an attic vent to the outside. I routed it up to the vent and attached the flex with pipe strap. Prior owner had no duct on the fan and it was venting directly into the attic.

FWIW, I have never used the bathroom vent!!
 
  #7  
Old 07-20-14, 12:31 PM
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Not exactly clear where it is vented, but if near a soffit vent (under the eaves) then much of the moisture and warm air will go right back into the attic.

I realize many home owners are not accustom to using exhaust fans, but trust me, you will need to be at some point in the future. When energy efficiency improvements are incorporated, the moisture must go.

Anyway, just trying to help.
Enjoy,
Bud
 
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