# Proper Vent Baffles: To be continuous or not?



## jcarlan (Dec 19, 2011)

We have a new addition w/ soffits (matches the vinyl siding) and ridge vents along the metal roof's peaks. The Proper Vent Baffles go from the soffits on the underside of the sheathing up into the kneewall triangular cavity. So the baffles pieces are only about 4 feet long. I removed a piece of sheetrock, popped my head into that unconditioned (cold & breezy) space and took the attached photo. Just inside that space I can reach up and feel another piece of baffle that goes up to the very small triangular space under the ridge vent. We questioned the disconnectivity of the baffles when they were installed but our GC insisted this was the way to do it. *Would it be better to run the baffles the entire length of the joists and insulate behind the baffles to keep the cold wind out of that kneewall cavity??*

We can definitely see the effect of the disconnected baffles on the North facing metal roof. The area without the baffle sections is first to melt. (Now, since we haven't taped the sheetrock we are sending SOME SMALL amount of heat through.) And we can also feel the difference in the upper floor rooms that have these kneewalls on their North and South sides. We have radiant heat in the floor of the living space. We live in VT.

Thanks for your advice,
Jean


----------



## dougp23 (Sep 20, 2011)

Hopefully a pro will weigh in. Just a DIYer here, but my thought is that if the baffles overlap, providing in effect a continuous length, the air leakage would be very minimal. If you are seeing melting spots, then you probably have a gap of several inches or a foot between pieces and that is not good, as air will not be able to flow.


----------



## Windows on Wash (Aug 30, 2011)

The kneewall, in most applications, is unconditioned space and the insulation layer is typically on the kneewall.

In that application, the baffles are not continuous nor are they ever air tight.

You are fine from a venting standpoint.

The insulation question is another thing that requires some repairs.


----------



## jcarlan (Dec 19, 2011)

oops -- here is the photo.


----------



## shazapple (Jun 30, 2011)

Yes, you should be fine from a venting standpoint. I would think about adding more insulation if you are worried abou tthe snowmelt.


----------



## Windows on Wash (Aug 30, 2011)

shazapple said:


> Yes, you should be fine from a venting standpoint. I would think about adding more insulation if you are worried abou tthe snowmelt.


More insulation and air seal the accessible structure.

Rigid foam and seal the kneewall up.


----------



## chb70 (Jan 29, 2009)

Baffle and insulation looks ok, make sure to air seal all penetrations coming into the attic where warm air can come through.

Basically your attic should be shut off from the rest of the house.
Add more insulation if needed.


----------



## Double-A (Dec 13, 2011)

Your contractor is correct in how it is done.

You want that section behind the knee wall to be vented.

If you want more insulation, insulate the back side of the inside wall, not the underside of the roof deck.


----------

