Clip-Vent, advertised in FH’s latest issue, is a black plastic extrusion that when used with rips of 1″ rigid foam, makes a double-flanged-with-spacer air chute that readily staples up into rafter or truss bays. A nice full width and rectangular-in-section vent chute is the result.
We are thinking this might be a good product to use for an upcoming project. The young feller shown in the pic that I clipped from their site can be seen getting one in place.
We’re buying our trusses with 12″ “energy” heels, which even though allowing some space for attic insulation thickness out to the edge, scrunches the height more than we like, and air vent chutes subtract from it.
At least we’ll get a nice R5 from the foam sheet we’ll use with the clip-vent arrangement.
Huttig distributes this product, so it ought to have pretty wide availability. Anybody used it and have some comments?
Replies
Gene,
Is this for a cathedral situation?
Chuck S
I am shocked that you would even consider this. You are a vetran BTer and you live in a cold climate. You should only be asking whether to go with a closed cell or open cell hot roof.
A. It's a spec house project.
B. The roof is not over cathedral ceiling
C. We do blown cellulose in cold attics to min depth of 18" except at the eave crunches, and supplement with PU foam in the tough spots
D. The ice dams can be seen on other roofs, but never on our projects
E. If you want us to build for you, and you so specify, we will be happy to give you a sprayfoam roof, and we will charge accordingly.
I kinda liked my scheme -- two pieces of 1x2 and a political yard sign.Anyway, you do need to do a sanity check for how long the chutes need to be, based on rafter angle and depth of insulation. For 18" of insulation in a 4/12 attic they need to be over 6 feet long, eg.(I'm sure you know this -- just pointing it out for others, since it surprised me a little.)
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Hot roof??
Have heard of it but never seen one. Our code (British Columbia) specs 65 mm air space, and ventillation, obviously for a cold roof.
On my own house, I used 2x12 rafters for cathedral ceilings, then stuffed in 2 layers of R22, from the bottom (rushing to get the roof on). The air space was not adequate had ice dams in all 6 valleys. Last summer I removed the metal roofing and simply pushed the FG down to fix the airspace. No more ice dams in valleys!
How does a hot roof work?
Hot roof aka an unvented attic. The attatched explains it.http://www.jlconline.com/cgi-bin/jlconline.storefront/45f9297f000f974927177f00000105a0/UserTemplate/82?s=45eaceff0018964427177f00000105d2&c=99bed6c24948e67882b7559f41b7f06d&p=1
Not sure if that was TIC or not. Not saying a hot roof can't work right, I just need you to send me a signed blank check so I can pay for it. Some people have the drudgery of building budgets. :-)