# How To Seal Tyvek Terminations At Wood And Composite Trim?



## gunner666 (Jul 16, 2014)

Hi, 

Tyveking then vinyl siding over t11. It's only the side of a building so there's no tyvek outside corner overlaps. 
I'm keeping the existing 1"x5" verticle pine corner trim, pine bargeboard along roof shingles, and composite window trim. There's no soffit (easier for water to penetrate).

Tyvek's pdf says tape or seal all terminations. If I tape it, I would have to cut the tyvek 1/2" short and reply on the tape holding for 50 years or something which I don't trust on painted, rough t11. If I tape it like an inside drywall corner half on tyvek and half on the 1" of pine trim/composite, then when the tape eventually peels away, water can probably enter easier than if I just bring the tyvek tight to trim and do nothing more. 

They tape Tyvek like an inside drywall corner here at 3:40, there's at least a soffit though. 

http://www.youtube.com/watch?v=kZeoR7cEEc0




The moderator of the siding forum here says silicone the joint. 
http://www.doityourself.com/forum/e...94-proper-vertical-termination-housewrap.html

But they're talking brick, not wood, so is the best option to use np1 polyurethane sealant which sticks to wood better than silicone? Polyurethane sealant is also recommended for pvc trim, and silicone might be incompatible.


So in other words, run the tyvek tight to the wood and composite terminations, caulk right behind the tyvek edge, press it down then caulk again to seal the tyvek to the wood/composite? 

someone suggested sliding aluminum sheet under the trim and sticking the tyvek tape to that, or what about pulling the trim out and putting the tyvek behind it instead?


Also, the windows might not have been properly flashed when installed, but I think it might just be risked to leave them how they are instead of pulling everything out and checking since it's a garage wall with no electric or anything behing the windows, it's not really my choice. So although I know that half say to never caulk between J channel and a window, in this case, if it's decided to not pull out the windows and trim and redo the flashing, should I space the j channel 1/4" from the existing composite trim, backer rod then polyurethane sealant?


thanks.


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## joecaption (Nov 30, 2011)

Posting some pictures of your own house would be a big help.
Your going to have almost mantaince free siding but your keeping the wood trim?
No way would I hold the J back from the trim and try and fill the gap!
Your going to have to add strips of Z moulding over all the tops of the doors and window trim before the J.
Ever sided a house before?


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## gunner666 (Jul 16, 2014)

there's already drip caps on the windows.

someone suggested:If you don't have the option of changing trim and flashing, then cut 1" back from the edge, then tape, setting the tape exactly into the corner, because it's easier to get the tape right into the corner. Small bead of caulk in the corner.


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## joecaption (Nov 30, 2011)

Why do you not have the option of changing or wrapping that trim so there's no more rot, painting or staining?
Without a picture we have no idea what the house looks like so I'm just approaching this from a practical stand point.
Dozens of times I've been in the position of having to go back and remove rotted trim, cover with coil stock long after it was siding years ago.
Would have been easier and less nails showing to have done this first before it was sided and trimmed out.


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## Windows on Wash (Aug 30, 2011)

Post up a picture of your home.


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## gunner666 (Jul 16, 2014)

I'm just going to remove the fasica/bargeboard and reinstall them over the tyvek... Becuase it seals better and is cheaper than tucking flashing under them especailyl since it's pressure treated t111 which will eat away at aluminum flashing, mayeb galvanized is okay and cheap, but copper/vinyl isn't cheap flashing and I already have the tyvek.

If really need be, then yes caulk behind the tyvek termination. From tyvek about best caulks to use:


Most sealants, butyls, polyurethanes, silicones, and acrylic latexes, are chemically compatible with DuPont™ Tyvek® membranes and DuPont FlashingSystems top sheets; however, not all of these sealants will exhibit high adhesion. DuPont assumes no obligation or liability whatsoever for the use of other manufacturers' 
sealants with our products.

http://www.dupont.com/content/dam/assets/products-and-services/construction-materials/assets/K-27282%20Chemical%20Compatibility%20of%20Representative%20Building%20Sealants%20FIN%2010.2.pdf


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