Replies

1. 
   braun247 | Nov 28, 2020 09:07am | #1

   You could try Smart Baffles by DCI.

   https://dciproducts.com/smartbaffle

   https://www.amazon.com/s?i=merchant-items&me=A1EVATRUSS0D3S

2. Expert Member
   BILL WICHERS | Nov 28, 2020 09:39am | #2

   I think the labor to put in housewrap vent “baffles” would be higher than you might expect. That material is going to flop all over as you try to get it straight, and generally fight you the entire time you’re working with it. You’ll also have the challenge of cutting long, straight-edged strips.

   Since the baffle material doesn’t have to be super strong, maybe just try 1/4” or even 1/8” hardboard, which is usually pretty cheap. A quick check shows 1/4” at $13/sheet and 1/8” at $8/sheet. The 1/4” would probably be the better option — less chance of breakage during installation. You could also use luan.

   Unfaced or rigid foam with vapor permeable facers would be another option.

   Bill

3. Expert Member
   Akos | Nov 28, 2020 10:33am | #3

   If you have wide flange I-Joists, it is pretty simple to staple up house wrap. Get one of the smaller rolls and cut the whole roll on a miter saw to the width between the joist webbs. You then staple as you unroll along the web.

   For narrower flange, as Bill suggested, 1/4" OSB/plywood is much easier to work with. You can also try cardboard or even ramboard.

1. Expert Member
   BILL WICHERS | Nov 28, 2020 11:56am | #5

   >"Get one of the smaller rolls and cut the whole roll on a miter saw to the width between the joist webbs."

   I like that idea! Have you had any issues with tear out though? Since housewrap is a random weave type of "fabric", I'm curious if the edges have a tendency to shread when cut with a saw.

   Cardboard might be a fire issue here. I'm not certain it would be a problem, but I know regular cardboard has no fire ratings and is more easily ignited than wood, so that may be a concern.

   Bill

1. Expert Member
   MALCOLM TAYLOR | Nov 28, 2020 03:31pm | #7

   Bill,

   I've even used a reciprocating saw on rolls of house-wrap without problems. A circular saw works on building paper too, but your blade gets all gummy.

4. 
   Jon_R | Nov 28, 2020 10:39am | #4

   Keep in mind that the intent is for moisture that makes it past the interior surface to harmlessly flow-through into the vent channel. So the vapor permeability ratio between the interior side (drywall, barrier, insulation) and the vent channel matters. How much depends on climate. But for less demanding walls, there is good support for 3x, 5x, and 15x in zones 5, 6 and 7. So something more for a ceiling.

   Say the interior side is 1 perm. I wouldn't use 3 perm foam to construct the channel (in Z5-Z7) - it would be an exterior side vapor retarder likely to cause some condensation and moisture retention.

   Highly permeable house wrap like Tyvek (56 perms) certainly wouldn't retain any Winter moisture. But with AC use, it might allow too much moisture in in the Summer, causing some condensation/sorption on the drywall. Better to use Typar (11.7 perms) in Z5 or Z6.

   Summary: in flow-through designs, perms matter - don't just use whatever is cheap and easy to construct vent channels.

5. 
   Patrick_OSullivan | Nov 28, 2020 01:17pm | #6

   How about 1/2" drywall? Perhaps use mold resistant board which, at time of this comment, is $14.67/sheet from Home Depot in quantity 1. Cheaper in quantity or at some other building supply.

   Given that mold resistant panels are rated for exterior soffits, I suspect it would be just fine as a vent baffle.

6. 
   timgodshall | Nov 28, 2020 09:02pm | #8

   Thanks for all the responses! I like the idea of cutting the roll of house wrap with a miter saw for a nice, clean cut. I think I'll give that a try and see how it goes - I'll post a follow-up in a few weeks to let you all know if it was miserable to install!

1. 
   igrigos | Mar 02, 2021 02:29pm | #9

   Any feedback on this process Tim? I'm considering this for our upcoming build and was curious as to how it went. Thanks!