The previous owner of my home replaced and added more windows. Unfortunately, many of them were not properly air sealed at the rough opening and, if I had to guess, maybe not well on the exterior sheathing side either. I'm not experiencing any signs of water intrusion or mold on the interior that I can see.

The windows are nearly all American Craftsman vinyl framed, LowE glass and installed into 6" deep walls (2 x 6 studs). There are three Anderson proper windows and an Anderson sliding glass door.

It's been very cold here in NJ and this amounts to many noticeable streams of cold air that emanate from around the interior window decorative trim that is installed around the drywall window opening on the inside wall.

There are unsealed gaps between the inside vinyl window frame and the wooden side jamb where the cold air also shoots through.

On the one hand, I'd love to figure out a way to get to the RO and pack in Rockwool bat and then seal over with Tescon Vana tape. However, I expect that's going to require me to rip apart the drywall.

On the other hand, I'm thinking the easier, but still effective for air infiltration stoppage would be to seal the gaps between the vinyl window frames and the inside jambs along with sealing the wall trim to both the side jambs and the drywall with a bead of Dynaflex 230. I realize this doesn't stop the cold air infiltration into the walls themselves and the associated cold/moisture sinking of the wall, but for an immediate comfort improvement, this seems the least expensive and deconstructive.

Any thoughts?

My husband grew up in NJ and he still complains about the cold Winters and hot humid Summers there... Dynaflex would be fine for sealing the exterior areas around the window trim. However, you might first want to remove some of the interior and exterior trim to see how these windows were flashed and sealed. If needed, you could then use a minimal-expanding polyurethane foam to accomplish better sealing. Please be sure NOT to use normal-expanding polyurethane foam as that could warp you window frames.

Thanks for the advice!

Tescon had advised I don't use any foam since after it's cured, it doesn't have any ability to compensate for expansion/contraction. The foam also doesn't allow moisture to escape. And, since my windows are vinyl, even low expansion foam could cause frame deflection. That's why he recommended stuffing the cavity with the Rockwool and then sealing with the tape. The Vana tape is moisture permeable, so this helps allow the cavity to "breathe" should moisture get trapped.

Yes, you definitely don’t want to create a cavity that is sealed with polyurethane foam or you could trap moisture. We always fill the entire space between the window buck and window frame with minimal-expansion polyurethane foam. However, we don’t use vinyl window frames and your warpage concern may be valid.

Honestly?  Given my druthers, I'd strip the trim and just deal with the drywall repair (just removing it back to the next stud over).

Backer rod (pick up a couple sizes).
Insert with a decent insulation pusher/spatula.
Then caulk (my preference: DAP Dynaflex 230 funnily enough).  You're going to want a couple tubes per window.
The caulk's between $3.10 and $5 per tube.  White and clear being cheapest.  Colored versions being more.

$3.10/per at Menards.
A 6 pack at Home Depot runs about $3.97/per (if you buy 4 or more it's $3.56/per.

You can find it at Lowes, Menards, Amazon, Ace Hardware (they want almost $7 a tube!)


I realize this might be a bit more work than you're willing to take on, especially during winter.

Caulking down the trim and recaulking the window/frame might make a small difference.


A halfway measure between the two might work as well, if you're willing to put in a bit more labor.  It's not even particularly destructive.

Strip the trim off.
See what you can fill with backer rod
Caulk the gaps.
Then make a decision if you want to back-caulk the trim as you put it back in.

Don't need to do any of that. If you are trying to seal the window from air infiltration simply caulk it . Caulk the window trim to the vinyl window and seal the trim to the dry wall. That simple. Cut the tip of the tube at the very end your not going to need alot. I would use a good quality acrylic latex with silicone. Have a damp rag handy to clean the edges. Should do the trick without taking the house apart. if you can get access to the outside,do the same thing there.