Spring Bronze Window Weatherstripping
Window weatherstripping stops air from sneaking around the sash into the home and also makes sashes slide more smoothly. The great thing about the bronze is that it can last for 100 years. The bronze is nailed onto the side jambs of the window, where the upper or lower sashes move up and down. When the window is closed, the weatherstrip is hidden, except for the 2 top inches, where it is taller than the lower sash.
See Diagram of the parts of a window.
Installation
Tools needed: tin snips, center punch, hammer, utility knife, screwdriver, measuring tape, caulk, caulk gun, 3/8" drill and drill bits.
Caution: You may be dealing with lead paint, so do not vacuum up any paint chips or dust created during this work, since this would send lead dust into the air. Wipe it up with water instead.
If a window is rattly, then remove the sash stop on one side of the frame. (The sash stop is the moulding between the interior-facing window casing and the lower sash that stops the sash from falling forward into the house. See the picture web-link above.)
Carefully run a sharp utility knife to cut the paint between the sash stop and the front casing. Score the paint well, because otherwise, the paint gets broken and looks horrible afterward. Also, this is probably lead paint and you don't want paint chips flying everywhere. Then unscrew the stop and take it off.
Slide a knife underneath the stop to lever it gently up in the center, where there is more give. (See photo and article on removing sashes and stops by the Old House Journal, "Window Secrets".) Don't break the stop. You need to reinstall it.
Wiggle the sash out. You should be able to do this without removing the other stop on the other side.
The sash will still be connected to the sash cords. Have someone hold it out of the way while another does the work. Have the bronze already measured and cut to be two inches taller than the sash would be when the window is fully closed.
Run a thin bead of caulk along the bronze on the side that will be against the jamb to seal this gap and fill in any irregularities in the surface of the jamb.
Put the bronze in place, along the sash channel. The bronze should cover from the base of the window frame to a height 2 inches higher than the top of the lower window sash when closed.
The open part of the V of the strip faces into the house. The narrow point faces the exterior of the house. This way the pressure of the wide part of the V pushes the lower sash in toward the upper sash, rather than away, so not opening up a gap between the 2 sashes at the meeting rail.
Nail the bronze into place. Keep it straight and be careful that it fits firmly against the sill, and so the strip won't get in the way of putting the stop back. Use bronze or stainless steel brads because where there is moisture, dissimilar metals can corrode the bronze over time. Put nails in every 1.5". Have the holes already drilled in the weatherstripping. Some jambs are made of extremely hard wood, so drilling pilot holes (using a drill bit that is slightly smaller than the brads) is necessary: otherwise, the brads will keep bending. In any case, pilot holes make the nailing easier.
Do the other side of the window sash channel. Put the sash back in place. Screw the stop back into place.
That's it.
(Addendum: If you want to avoid the step of taking the window stop off and removing the lower sash, I have been told you can possibly open the window the normal way (i.e. move the lower sash up as high as possible), then feed the bronze V-Seal up another inch or two between sash and frame, so it’s high enough that it’s not going to get caught by the lower sash moving up and down. Then you nail it in. If anyone tries this and it works, let us know.
