Anyone who owns or lives in a house with traditional timber framed sliding sash windows, will know that the operating cords will require replacing at some stage.
Although they have been part of our architectural scene for the best part of three centuries, the basic design has changed very little.
As a carpenter, I worked for many years on the repair and maintenance of many types of Georgian, Victorian and Edwardian sliding sash windows. Now, it is time to pass on some of the skills that I learned over the years.
The best way that I can do this, is to put it in writing for posterity as I believe these skills will in time be lost, due to the proliferation of modern plastic and aluminum windows.
Having said that, the basic instructions for renewing the cords by which the balancing weights are suspended have not changed much in a good many years, if ever!
So, looking at a sash window from the inside, you will see that the sliding sashes or frames are held in place in the box frame of the window by moulded timber beads (staff beads) at the top, bottom and both sides. They will usually be pinned or nailed, very occasionally screwed to the box-frame of the window, the heads of the nails or pins will usually have been punched in with the holes filled and painted over, making them invisible for a cleaner, better finish.
To gain access to the cords and weights, you have to first remove both the side staff beads. When replacing the top sash cords, it is possible to only remove one staff bead, but I prefer to remove both for ease of access and would advise anyone inexperienced to do likewise.
The purpose of these instructions, is for the use of persons of amateur status but having had some previous experience of using basic carpentry tools.
When removing a staff bead, it is best to use an old wood chisel, the wider the better and one that you have no qualms about ruining its edge by hitting hidden nails, which invariably happens.
Placing the chisel in the groove, between the staff bead and the box frame, and strike firmly with a standard hammer. Lever the bead away from the box-frame. Repeat this action at several points from top to bottom of the staff bead. Having loosened the bead sufficiently, it should be easy to spring the bead away from the box-frame. Now repeat the same on the other staff bead.
Next, you need to make sure that you remove all nails from the window frame, and remove any old caulk or filler adhering to the frame, and you can now remove the lower sash frame from the box-frame, having, of course removed any existing cords first.
When removing existing old cords from the sashes, care must be taken to pull the weights to their highest point and holding the cord tightly, cut it away from the sash with a sharp pair of side cutters and gently lower the weight as near the bottom of the frame before releasing it. Carelessly dropping larger weights can cause damage to the frame and even result in the weight descending into the wall cavity from whence it can be very difficult to extricate!
Then remove all remnants of cord from the sashes, noting the method by which they are attached to the sash, so that you can replace the new cord in the same manner.
Now you can completely remove the inside bottom sash from the box frame.
You will now see a narrow strip on each side of the box frame, running from top to bottom of the frame and set in an eight mm. groove and separating the two sash frames and also helping to draught proof the window. These are known as parting beads and should fit tightly into their grooves.
Lever these out of their grooves using a sharper wood chisel. To make this easier and to avoid damaging the beads, it is advisable to run a sharp stanley knife down each side of the beads to break the seal of the paint.
Removing these beads will free the outer sash frame, so that any existing cords can be removed as before and the sash can now be remove from the frame. Do not forget to gently lower the weights as before when removing the cords!
At this stage, it is wise to move the sash frames out of the work area as it is so easy to damage the glass if they are close while you are working on the box frame. I have often had hammers and other tools fall off the window sill and break glass! Not only expensive, but also very time consuming and downright annoying.
On each side of the now empty sash window box frame, you will now see a cut out strip of timber which is known as a pocket. Depending on the condition of the window, these may be quite loose fitting and obvious or they maybe tightly fitted and hidden under layers of paint. Either way, they should not be too difficult to locate and remove. When working on several windows in the same room, it is advisable to number these to make it easier when replacing them.
Removing these pockets,will expose the iron or lead weights,which can now be removed. If the size of the weights are different, note their position. Generally, the rear weights will be pound heavier than the front ones to allow for the heavier inside frame which has a much heavier bottom rail. It is very important to replace the weights in their original positions to ensure the smooth operation of the sashes.
Before fitting new cords and replacing the weights and pockets, it is time to clean up the box frame. In fact, if any repairs or renovations are planned, now is the time to do it. It being far easier to carry out glass and putty repairs and replacement and to repair any defects to the timber whilst the window is dismantled.
It may also be the time to consider additional draught proofing seals, new locks and repainting at the same time.
When replacing the cords, you will require a simple home made tool known as a 'mouse', This is just a length (approx.2 metres) of strong string or thin cord, with a small piece of lead fitted to one end. this must be small enough to go through the gap the top of the pulleys of your box frame.
First, thread the mouse into the gap at the top of your front pulley and allow it to fall inside the box, now attach a length of new cord to the other end of the string. locating the 'mouse' through the pocket, gently pull the string over the pulley, followed by the new cord down to the pocket, where you can now re-attach the iron weight to the new cord and pull the weight to the top of the frame, cut the cord to the required length and knot it so that the eight is suspended inside the frame. Repeat this for all four cords and weights.
As a rough guide, when the weight is suspended at the top of the frame, your new cord should be long enough to reach halfway down the length of the pocket. This should allow you plenty of cord to thread and knot into the side of your sash frame. (Sometime it is necessary to screw or nail the cord to the sash frame, depending on design or condition.) To keep the weight suspend at the top, I usually use a panel pin through the cord into the box frame. This also allows you to be hands free when placing the sash frame in position and re-attaching the cord to the sides.
When the cords are re-attached to the front sash frame, they should be long enough to lower the frame so that the top rail is approx. half-way down and the bottom rail does not quite reach the outer sill. This is usually a matter of trial and error, but gets easier with practice!
At this stage, the two pockets can be replaced, making sure that they are as flush to the frame as possible. If they are loose fitting, it may be necessary to use a panel pin or two to keep them from hindering the sash frames.
Now replace the parting beads in their grooves and again if loose, panel pins can be used to secure them. If the beads are damaged or show signs of rot, it may be best to renew them completely. Most DIY outlets stock this item, also some builders merchants. It will be found though that modern bead is generally slightly thicker than original beads and may need to be planed down by a couple milimetres.
Now replace the inner or bottom sash frame, making sure that the bottom rail sits tightly on the outer sill, and that the meeting rail is level and that the window catch lines up.
All that remains, is to replace the staff beads, making sure that they are not too tight to allow the sash frames to move, but tight enough to avoid excessive movement and rattling in windy weather! To do this, it is best to secure the beads with three or four forty millimetre panel pins, only drive the pin about halfway in to start. Use a piece of card or an old credit or tradecard between the sash frame and the bead as a spacer, and when you are happy with it, drive the pin home. Job done.
Great deals with replacing sash windows at steel windows.
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