Attic baffles--How many?

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Old 01-06-17, 07:31 AM
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Attic baffles--How many?

Considering adding blown-in cellulose to my inadequate attic insulation. There are no baffles up there at all so my question is whether I would need to install one at every bay, or only those with a vent at the eave end?
 
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Old 01-06-17, 11:59 AM
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Baffles

I recommend every bay in order to keep the insulation from going into the soffit.
 
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Old 01-06-17, 12:29 PM
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Blocking the insulation as wirepuller said is a high priority. In addition, you need/want air flow below the bottom of the roof in every bay. And those baffles should have a flap at the bottom to drop down and protect the end of the insulation from incoming air flow, called wind washing.

Make sure you have sufficient NFA (net free area) from the current vents and that the soffit construction is open between rafters such that air is available to all rafters.

Also, before you bury everything in new insulation review the air sealing requirements, very important and now would be the time. https://www.energystar.gov/ia/partne...ide_062507.pdf

Bud
 
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Old 01-07-17, 07:37 AM
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I've lived in this house 23 years with R13 batts in the attic. If I start questioning whether the air sealing and flow is correct I will NEVER get this done.
 
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Old 01-07-17, 08:21 AM
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I understand what you are saying, BUT, air sealing is a higher priority than insulation and there is a compromise. 90% of that leakage is happening through major leaks and they are often easy to find.
*Your plumbing vents often run from basement to attic.
*Chimneys, metal or brick if you have any, need clearance to combustibles but that gap can be closed with metal flashing.
*Drains under showers or tubs are often excessive and connect to other paths to reach the attic.
*Drop ceilings over cabinets are often open to the spaces above.
*A porch roof may be connected to the framing without sheathing that provides the air barrier.

If you can, great, but consider searching from the basement as an alternative if you can't.

Bud
 
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