Replies

1. 
   user-1105327 | Mar 10, 2013 05:27pm | #1

   ps, i posted the screenshot of the siga webpage because i did not see something resembling tyvek as a suitable substrate..

2. 
   albertrooks | Mar 11, 2013 09:43am | #2

   Erik,
   It's best to cut the Tyvek back and have the Corvum 12/48 stick directly to the framing. You mentioned that it would be sticking to OSB. If it is the rough side of OSB, then I'd be prepared to apply Siga Dockskin primer on the OSB.

   I say this because while Martin wrote in Fine Home Building's tape article (out last week), that he felt that Siga Wigluv did not need a primer in his application, it probably will when you join Corvum 12/48 to OSB. Especially so if it joins to the rough side of OSB.

   Corvum 12/48 uses a heavy paper backing where Wigluv uses a flexible polyolefin. The heavy backing of Corvum is stiff enough to have a "memory" and will tend to "straighten itself out".

   We had this happen to a builder Alaska. At application, the bond seemed fine and the Corvum was adhering well to the irregular surface of the OSB. Weeks later, the strength of the backing paper wa stronger than the bond to the OSB and it started to straighten out.

   If you apply Dockskin Primer to the OSB first: The primer acts as kind of a "filler" and creates a "flatter" surface. It also increases the bond strength. That's because the rough side of OSB out here in the west is really fibrous at the surface. The adhesive will stick to the fibers,but the fibers don't stick to the board.

   So yes, cut the Tyvek back and if it's OSB, have some primer on hand. It can really help create a permanent bond.

3. 
   user-1105327 | Mar 11, 2013 11:17am | #3

   thanks, albert. i bought corvum 30/30. if the 12/48 is indeed 12mm, that makes the window leg of the tape less than 1/2". around here, typical window r.o.'s are 1" less than the actual window dimensions. that means, in a perfect world, there will be a 1/2" gap between the installed window and the framing. in reality, this gap could be all over the map. that said, the 12mm leg won't span the gap. furthermore, many fibreglass and vinyl windows have a kerf or return or some sort of thermal break around the perimeter of the window so even if the 12mm leg made it to the window, it would still need to go beyond the kerf to get any real material to bond to...
   am i missing something? or is the tape designed for unique swiss windows...

4. 
   albertrooks | Mar 11, 2013 11:45am | #4

   Erik,

   It's a common thought that the fold goes at the RO. The 12/48 has a 12mm leg so that you can place the fold at the window edge and know that it will not protrude past 1/2" for drywall or casing. The idea is that you use the 48mm leg to span the gap caused by shims etc. Since it's a gap, a 90 degree bend isn't required.

   The Swiss use the same gaps as we do in the US. Many people have made this same assumption. We should probably be more clear on our website about this design.

   Btw... If you aren't aware of how to go around around the window with pre folded corners, see this: https://www.youtube.com/watch?v=5Q96tfAtekg&list=PL9CE2B3FD53623030&index=3

   I guess it's confusing that in this video Benjamin is using an application with a small shim gap. That's not the normal case. Gaps are usually 3/8" to 1/2". I can see how one would make the no gap assumption.

5. 
   elyk22 | Nov 08, 2015 09:10am | #5

   Hi, I know this is an old thread but similar to what I'm dealing with.

   My vinyl windows have the 1/8" kerf on the outside profile (for drywall return edge). I have corvum adhered to the kerf, across foam gap to plywood jamb.

   I can't get any more window area to stick to as we are doing drywall returns, so the kerf is the only available part.

   I'm wondering overtime with window expansion and movement, if the bond of the tape could break the kerf off the window? Or if the 1/8 adherence to the window will fail as it is not a wide enough bond.

   Thanks Kyle

6. GBA Editor
   Martin Holladay | Nov 08, 2015 10:01am | #6

   Kyle,
   It's hard to say. Most European specialty tapes are surprisingly tenacious. If you press down well to make a good bond, 1/8 might be enough (although 1/4 inch or 3/8 inch would obviously be better).