Scrape off large clumps of accumulated paint from the inside and outside faces of the sashes, as these will impede free sliding. Sand these surfaces smooth. It's best to paint double hung sash while they are out of the jambs since the parting bead and inside stop aren't in the way, but to do so you have to leave the windows out of the jamb for a night or two. Don't paint the edges of the sash, as this will contribute to binding. Wax the sash edges with paste floor or furniture wax, butcher's wax, or by rubbing the butt of a candle on them (photo 7).
Photo 7- Wax the sash edges so they will slide smoothly.
Scrape paint clumps from the jambs where the sash slide (photo 8). It's best not to paint these areas at all and cover them with wax, but older ones are usually painted so just level the paint and wax it to help the sliding sash.
Tie knots in the ropes to fit in the knot holes on the sash edges. Carefully locate the knot on the rope so that the sash will travel its full height with the weights counterbalancing it. The inside sash needs to travel the whole length of the jambs, but the outside sash, which is the upper when closed, need only slide down a foot or more for upper room ventilation on hot summer days.
Photo 9- Install the new rope into the sash. Be careful where you tie the knot that fits into the sash, so that the weights will have full travel.
Photo 10- Replace the outer sash.
Hold the outer sash up to the jambs and place the rope knots into the holes in the sash edge (photo 9). Drive one small nail through the knot and into the wood behind to hold the knot in place. Next tilt the sash into the jambs (photo 10), and replace the parting bead (photo 11). Now you're ready to replace the inside sash in the same way. Finally replace the interior trim and the inside stop which holds the inside sash in its slot (photo 12). Carefully locate this stop so that it does not bind against the sash, but is tight enough against it to keep it from rattling in the wind and reduce cold air intrusion.
Use caulk to begin repairing the chipped paint. Caulk along the edges of the inside stop where it meets the jamb inside the room and on either side of the interior trim where it meets jamb and wallboard, if you had to remove it. Run your finger along the caulk after application to smooth it, making a clean transition between parts that covers broken edges and paint. When the caulk is dry, set the nail heads in the wood about 1/8" with a nail set, then fill the holes with spackling paste. Sand the dry spackle, prime, the spackle again when the primer is dry to fill any spots you missed. Sand this spackle when dry, then apply top coat.
Caulk the parting bead on the outside face where it meets the jamb to inhibit water intrusion, caulking the bottom edge of the piece well too. When painting the sash in place, use a small brush and be very careful at the sides not to get paint between the sashes and the parting bead or stops. Don't get any paint on the ropes or pulleys. A few drops of oil on the pulleys will help preserve that easy sliding action that makes double hungs such a simple pleasure to use.
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