Replacing sash window cords
Over time, the cords on sash windows do wear and ideally they should be replaced before any actually break.
If a cord should break, the sash will be unsupported on that side and the sash weight will drop to the bottom of the frame behind the window side stiles. In some sash windows, there is no 'bottom' behind the side stiles (either by design or by the section of timber rotting away), in which case, the weight will drop to the bottom of the wall cavity!
To replace a sash cord, the sash needs to be removed from the fixed framework, usually it is worth while renewing all the sash cords on a window at the same time.
Before starting work, lower both sashes as far as possible, if they become jammed before reaching the bottom sill, support them with something, possibly use thin wedges between the sides of each sash and the side stiles. If the sashes are left unsupported, they may drop when the beadings are removed which could break the glass - support is especially important if both cords on a sash are broken.
Sash Removal
Cord replacement requires the sashes to be removed from the framework.
Working inside the window, remove the two side staff beads - the upper and lower staff beads can be left in place. The side staff beads are attached to the window frame by nails, care needs to be taken so that they are carefully eased off the framework to avoid them breaking. Start half way up each side using a thin, wide chisel to lift the bead, and work up and down towards the two corners bowing the bead to spring it out of the mitres at the top and bottom.
With the staff beads removed, the internal sash will no longer be held in its channel on the side stiles.
- If both sash cords are broken on this sash, lift the sash out.
- If either or both of the sash cords are intact, lift the sash up and support it. Take hold of the sash cord above the sash and either:
- Pull the sash out of the frame and remove the nails holding the cord to the side of the sash.
or
- Pull the cord away from the side stiles and cut it through using a sharp knife between where you are holding and the top of the sash.
- Pull the sash out of the frame and remove the nails holding the cord to the side of the sash.
With the internal sash removed, the parting beads (which run vertically between the two sashes on each side) can be removed. Normally the parting bead is just a tight push fit into a groove in the side stiles, don't use too much force as the bead can easily be split, the biggest hindrance to their removal will probably be found to be paint built up from many coats of painting the window frame over the years - remove as much paint as possible, using a sharp decorators filling knife to cut through the coats of paint may help.
Once the parting beads have been removed, remove the outer sash from the frame in a similar manner as the inner sash above - i.e. if either sash cord is intact, either remove the nails holding the cord to the sash or cut the cord - knot the cord so that the knot jams into the pulley.
If any of the cords were cut, remove the remains of the cords attached to the sides of the sashes by extracting the nails - normally large headed (clout) nails are used, so they can usually be removed using pincers.
Remove the weights
With the parting beads removed, you should see the edges of the Pocket covers which allow access to the weights near the bottom on each side stile - the Pocket covers are elongated removable sections of the side stiles which extend to behind the parting bead. Remove the Pocket covers; this may need paint to be removed.
With access through the side stiles, remove the weights. Where the cords were previously knotted, untie the knots and tie a length (a least twice the height of the side stiles) of thin twine to the end, then feed the cord and twine over the pulley allowing the weight to drop, once at the bottom of the side stile the weight can be lifted out and the cord pulled through so that the twine emerges. Tie the two ends of the twine together so that it forms a continuous loop over the pulley and down the back of the stile.
Where a cord has broken, there won't be a length of cord to pull through over the pulley. So to get a length of twine into place, make up a 'Mouse' to feed the twine down the back of the side stile. A 'mouse' simply consists of a small piece (about 30mm) of thin lead which is rolled around a length of twine. The diameter of the rolled lead needs to be small enough that it will pass over the pulley, the lead will then drop behind the side stile to the bottom where it can be pulled through the pocket access, cut off the mouse leaving about 300mm (1 ft) of twine so that the mouse can be reused. The two ends of the twine should be tied together to form a loop over the pulley.
Check the weights as they are removed - usually all the weights are the same size/weight for a given window, but if they do vary, mark the weights so that they can be reinstalled with the correct sash.
Remove the old cord from the weights - the cord will often have stiffened over time, so you may need to use some force to remove the knot from the slot.
Check the pulleys
Check that the pulleys at the top of the side stiles turn freely, but not loosely on their spindles. If a pulley only turns stiffly, apply a drop or two of oil to the spindles and work them until they turn freely.
If the pulley is seized solid or is very loose on the spindle, the pulley assembly needs to be replaced; they are usually held in by a screw into the stiles above and below the pulley itself.
Working out the length of cord
Sash cord is special cord which won't stretch and normally comes in a 'hank', do not cut the cord before fitting the weights behind the side stiles and measuring the length required.
The length of the new sash cords will need to be determined for each sash, to do this:
- Measure the distance from the bottom of the cord slot on the side of the sash to the bottom of the sash - see right.
Mark the distance on the side stile measuring up from the bottom of the frame - see right. When the stage is reached to cut the cord, the final measurement will be taken from these marks. - Do this for both the inner and outer sashes.
Fitting new cords
Starting with the outer sash, tie the end of the new sash cord to the twine over the sash pulley on one side, with one hand taking up the slack of the twine through the pocket access, feed the new sash cord over the pulley and allow it to drop down behind the side stile and pull the cord through the pocket access.
Remove the twine from the end of the cord and feed the cord through the hole in the appropriate weight and tie a knot. Take care to ensure that the knot does not protrude outside of the weight, if necessary, hammer the knot into the weight to reduce the size.
Take up the slack of the cord over the pulley with one hand and feed the weight through the pocket access into behind the side stile and pull the weight to the top. With the weight at the top, put a pin through the cord into the side stile under the pulley to prevent the weight from dropping.
Pull the cord tight down the side stile to the mark previous made, mark and cut the cord.
Repeat the above for the weight on the opposite side of the sash.
With both cords for the sash now cut to length, offer up the sash (make sure that you use the correct sash and that it is the correct way around) and fix each cord into the groove on the side of the sash using appropriate nails - don't nail the cord right to the top of the sash, the distance from the topmost nail to the top of the sash needs to be at least as great as the distance from the middle of the pulley to the top of the side stile. Make sure that the nails are hammered below the side surfaces of the sash to ensure free movement of the sash in the frame.
When both cords have been attached, position the sash in the frame and remove the pins holding the sash cords at the pulleys, check that the sash moves freely up and down and that when the sash is at the top, the weights are clear of the sill behind the side stiles at the bottom.
Insert the parting beads in both sides, you will need to leave the bottom of each bead out of the groove until you have finished and can replace the pocket covers.
Hang the weights, cutting the cords and fix the cords to the inner (lower) sash using the same procedure.
Position the inner sash in the frame and remove the pins holding the sash cords at the pulleys, check that the sash moves freely up and down and that the sash will remain in the bottom position.
Pull the sash out of the frame, replace the pocket covers and secure the parting bead - do not use any glue or nails etc.
Replace the sash in the frame and fit the staff beads to each side, spring the beads back into the corner mitres and nail in place - do not nail nearer the corners than the original nails as to do so may prevent the bead from being sprung out the next time they need to be removed.
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