Many historic buildings around the world are constructed with double hung sash windows. Unfortunately, many of these historic windows are lost to rot and replaced with inferior alternatives. Don’t let this happen to you! This simple maintenance procedure will return your windows to their rightful glory both aesthetically and functionally for decades to come.
Before getting started, it is important to test your windows for lead paint. Inexpensive self-test kits are available at your local paint store. If you discover lead paint, it might be necessary to initiate an abatement process with a certified technician. Also, local codes may dictate that you must consult your city’s historic preservation commission before preforming the maintenance procedures outlined here.
1. The first step is to remove the interior stops either by unscrewing or gently prying. Don’t break the stops! Try to get your prying tool in right next to a nail and work your way up the stop.
2. Now that the stops are off, the lower sash should come right out. If your sash cords are in good shape and you will be reusing them, knot the ends so they do not disappear inside the frame.
3. Remove either the parting bead or the exterior stop to free the upper sash. One option might be easier than the other, depending on how it is nailed together. It might be necessary to carefully saw through nails with a reciprocating saw in order to get the parting bead or exterior stop out cleanly. Study the construction well before deciding.
4. Carefully remove the upper sash. It may be fixed in place, but it shouldn’t be! A proper double-hung window allows the upper sash to come down. By leaving equal openings at the top and bottom, warm air exits the window above and cool air is drawn in below.
5. Now that both sashes are free, scrape away any old or loose glazing compound on the exterior side. A heat gun will help soften up the glazing. If the glass is broken, you’ll have to remove all the glazing. That will reveal the metal glazier’s points that hold in the glass. Remove the glazier’s points and the glass is free to come out.
6. If there is rot (especially common on the underside of the lower sash), use a probe to remove any remaining soft material. Fill all voids with two part epoxy and use a plastic scraper to scrape the epoxy flush. If you discover that a sash is too rotten to reuse, Eco Relics has hundreds of wooden sash windows to match yours!
7. After the epoxy has cured for 24 hours, carefully scrape and sand the sashes on all sides to prepare for paint. Now prime and paint both sashes, but leave the sides unpainted! The sashes will slide easier if this surface is waxed rather than painted.
8. Replace the glass (if you removed it) and press in the glazier’s points to hold the glass in place. If new glass is required, come on in to Eco Relics and score some vintage wavy glass to match your other windows.
9. Glaze in the glass on the exterior side of the sash with glazing compound and a stainless glazing tool. The trick to getting clean glazing lines is to get even pressure on the tool against the glass on one side and against the wood on the other side. It takes some practice, especially in the corners, but you should be rolling right along after your first sash or two.
10. Apply a coat of paint to the glazing after it dries. It may take up to 15 days for the glazing to dry, so this step may be preformed after the sashes are reinstalled. It is important to paint the sash before applying the glazing because the bare wood will suck the oil from the glazing compound, causing it to crack prematurely. Then another coat of paint over the top of the glazing is necessary.
11. Now that your sashes are ready to reinstall, it is time to prepare the frame. If you are replacing sash cords or reattaching the sashes to the counterweights, you’ll need to gain access to the counterweight pocket inside the window frame. Usually this is as easy as removing the access panel in the track. If your window lacks an access panel, you must access the counterweight pocket by carefully removing the inside facing from the from the window frame. Pass the new sash cord (braided nylon works well in our humid climate) through the pulley and tie off the end to the counterweight. Leave the cord long enough to allow the sash to open and close completely, but short enough to keep the counterweight from resting on the bottom when the sash is up. Knot the other end to prevent it from falling through. Are you missing a few counterweights? Good thing Eco Relics has them for you!
12. Lightly sand the tracks which the sashes slide against, then wax the tracks with either beeswax or paraffin. Do not paint the tracks! The sashes will slide much easier against an unpainted waxed surface. If the tracks are already painted, it might be too much trouble to remove all the paint. If so, sand the tracks smooth and paint them with a high gloss paint to aid in trouble-free sliding. Wax may also be applied over the paint.
13. Wax the sides of the sashes before reinstalling. Place the knotted end of the sash cord in the side of the sash and secure it with a finish nail. Punch the nail in to be sure it will not snag when the sash slides. Test the cord length, because this is the easy time to change it!
14. With the sashes installed and the counterweights tied off, it is time to reassemble the frame. Start by securing the upper sash with either the exterior stop or the parting bead, whichever one you removed to free the upper sash. Nail in the parting bead or exterior stop with finish nails while holding it snug against the sash. Make sure it is snug all the way up and down the track, but not so tight that it impedes the sash from sliding. Repeat the process with the lower sash and interior stop.
15. Optional – There are several strategies for increasing the efficiency of your old windows, but you might find it unnecessary in Florida’s mild climate. If your windows are just too drafty, try adding curtains that land on the sill or the floor. Return rods allow the curtains to meet the wall, which will help create a pocket of still air around the window. Another option is to add storm windows to the exterior.
Congratulations! You’ve just rehabilitated one of the principle architectural features in your home! Now your sashes should slide easily and look beautiful for decades to come. If you have freed the upper sash, you have also just significantly increased your ability to passively cool your home by leaving equal openings at the top and bottom of your window. You can also open only the upper sash to ventilate during a rainstorm. Won’t your neighbors be jealous!
If you need supplies, the Eco Relics architectural salvage warehouse has the largest selection of salvaged wood framed sash windows, counterweights, and more.