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Discussion Starter · #1 ·
I've been trying to educate myself on insulation and while I understand the purpose of ventilation baffles but I'm not understanding the purpose about the common design.

I see that all ventilation baffles provide 1"-2" air channel and the baffles are any where from 2'-5' long.

Why are baffles not going more than 5' and not just all the way up and really close to the roof ridge?
 

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They are in short lengths, 1) because they are frail 2) most situations are unfinished attics so they extend just far enough to keep the area clear of insulation where the rafter meets the top plate of wall 3) if you have an insulated roof and need to extend up to ridge then you connect multiple ones

Only if they are reflective would they be a radiant barrier, and even then the fastening lips and lack of going over the rafters would negate the effectiveness.
 

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Discussion Starter · #5 · (Edited)
They are in short lengths, 1) because they are frail 2) most situations are unfinished attics so they extend just far enough to keep the area clear of insulation where the rafter meets the top plate of wall 3) if you have an insulated roof and need to extend up to ridge then you connect multiple ones

Only if they are reflective would they be a radiant barrier, and even then the fastening lips and lack of going over the rafters would negate the effectiveness.
Thanks. So my thought is to remove my existing flimsy baffles which are also not sealed at all at the top plate. I would make new baffles out of foam board, along with a vertical piece for the top plate and all sealed with canned spray foam. That should be rigid enough.

A 60's home 1000sq/ft with blown insulation about 20 years go. I'm thinking of removing all insulation, building the baffles, filling ceiling air gaps, and putting rockwool between joists and then another rockwool layer perpendicular.
 

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All they are doing is keeping the insulation from blocking air flow from the soffit vent to the upper venting. No sealing is needed, and strength shouldn't be a concern. The vertical dam would be for blow-in insulation to prevent it from entering the soffit overhang. Do you have a pic of what you have and describe what your end game is?
 

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Discussion Starter · #7 ·
All they are doing is keeping the insulation from blocking air flow from the soffit vent to the upper venting. No sealing is needed, and strength shouldn't be a concern. The vertical dam would be for blow-in insulation to prevent it from entering the soffit overhang. Do you have a pic of what you have and describe what your end game is?
This house is in South NJ near the coast. Pretty humid at times.

The vertical part of the baffle would be to also reduce wind/air over the insulation.

Something like this:


The current state of things:

 
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