# Attic insulation quotes, to add baffles or not?



## jimn (Nov 13, 2010)

As a general rule, if you have soffit vents you need the baffles to prevent the insulation from blocking the air flow. You might want your contractor to calculate the square footage of vents required to make sure they are adequate


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## Windows on Wash (Aug 30, 2011)

The last picture is okay but the proceeding ones are not good. 

The baffles MUST be there and the ventilation must be continuous and balanced.


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## joecaption (Nov 30, 2011)

Take your finger and put it over the end of a straw and suck on it, how's that working for you?
Works the same way in an attic, those gable vents need makeup air to work.
If the soffits are blocked it can create a negative pressure in the attic and start to draw the conditioned air from the house envelope.
Anyone mention air sealing before adding more insulation?
Google "insulation zone map" to see what's the minimum levels of insulation needed.


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## Gary in WA (Mar 11, 2009)

The bids are not following our WA State Code which REQUIRES baffles for a (minimum) 1" air space. They should have told you that;* pp. 67 and 77*; https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CD0QFjAB&url=https%3A%2F%2Ffortress.wa.gov%2Fga%2Fapps%2Fsbcc%2FFile.ashx%3Fcid%3D1223&ei=N-7FUrjHF4nooAStwIHABQ&usg=AFQjCNGIitdjv1IcgePJn9ghIkcdQIb5Yw&bvm=bv.58187178,d.cGU

As you don't have moisture problems, it may be working as is. The gable vents supply/exhaust each other as the wind seldom blows in both ends at same time to pressurize/depressurize the attic. http://archive.nrc-cnrc.gc.ca/obj/irc/doc/pubs/bpn/57_e.pdf 
With the existing 14 soffit vents (- that you would be using room air), you may have an efficient system now. Problem is; covering the existing air space (one pic with builders paper creating chute) with the new blow-in. Also, any insulation touching the roof sheathing *conducts *your room heat to the cold temps outside, another reason for the baffles. As Joe said, air seal; first and foremost. 

As warm air rises (passive effect) and exits a gable vent, colder (denser) air enters the soffits (pushing warm air out); or if restricted by insulation- in addition- through the other gable vent (wind pressure). IMO, add a ridge vent when noticing moisture in the future (if you decided not to baffle)- requires checking- sooner than just annually.

Read; "
*“Warm air rises, cool air is sucked in to replace it.”"*

And; 
*"Heat rises." * from; http://learn-science.20m.com/tmyths.htm#myth2

Gary


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