Air seal windows or leave alone?
 

I have double hung double pane vinyl windows throughout my house. It looks like when they installed the windows and doors they used fiberglass as insulation around the casement. They installed drywall right up to the window except for the window sill which is a board.

In an effort to help air seal for now, I put silicone caulk around the window to air seal to the drywall. I don't feel any air coming around the window any more, but i wondered if that meant it was going into the wall.

Should i remove the drywall around all of my windows in order to remove the fiberglass and install great stuff? I would install wood trim around the windows if I have to remove the drywall, since it would be easier for me.

I already have done this for my doors as they had wood trim.

One other thing: In a few years, I plan on taking the siding off the house, adding 2" of foil faced polyiso and putting metal siding on. I wasn't sure if i should remove the windows when I do this in order to make the windows flush with the exterior to help with rain. If I install touch foam, this would make the windows harder to remove. Suggestions here?

Great stuff, or equivalent foam, is so much better than fiberglass for sealing around windows, that you'll probably wonder why you wasted so much time thinking about it.

I think that you definitely should dig out the fiberglass and foam the perimeters of the windows.

Regular great stuff keeps expanding into its hardening phase, and can distort a vinyl frame so that the window doesn't close easily, or at all. I ended up using regular GS at the corners for strength, and low-expansion for the sides and top & bottom. Worked good.

If you're going to do the wrap and re-siding this summer, it might be a good idea to wait. But if you're like me, and it takes a while to get stuff finished, foam now and live with the results when that remodel time actually comes.

I don't know if your windows are mounted with 'fins' on the outside or not but if not, removing the windows should be quite easy. Some very careful use of a repiprocating saw or even a small electric chainsaw would make removing the foam a snap.

-AC_Hacker

The reason I wasn't sure it would do anything is because I basically have a drywall air barrier. I think they are new install so have the fins.

Has anyone heard of adding insulation on the outside, leaving the windows 2" in, and using trim to hide the difference?

Yeah, thats not all that uncommon. Some people are even adding 4" of insulation on the outside.

I would suggest going with extruded polystyrene though. If polyiso gets wet it looses its r-value, and being sheathing this is fairly likely to happen.

If you do add insulation to the outside and install new siding pay special attention to the top of the window, and install a proper drip flashing to direct water away from the window. Many newer vinyl windows have a "J" feature all the way around the window, and this can be buried under the buildout, losing the drip protection.

It's common to do that with new siding, my house has foam over the old siding then the new siding over that, trim on it is just painted flashing, I like the metal trim as it lasts a long time and only needs paint touched up every 20-30 years.

As for around your windows, it sounds like you don't have any trim around them? that makes thins more annoying but you can still work with it, adding trim would be the easiest route.
The fiberglass you have is more or less slowing the cold air down and filtering out the dirt, when you go to pull the fiberglass out you will find a ton of dirt trapped in it, cold air is then getting to the back side of the dry wall that is around the window, if you had a thermal image of the wall you would see that space as a cold spot all around your window.

Last year my back door and bathroom window were replaced by my wife's cousin who does renovations. He fabbed up the trim by making cardboard templates and going to a local window place to get the flat trim which he then shaped.