How To Replace Sash Cords
One of the simplest job you can undertake with your sash windows is a simple re-cord. At first it may look like an incredibly difficult job but believe it or not can be very straight forward and completed in less than an hour. Firstly you will want to remove the inside profile known as staff bead. You want a chisel with atleast an inch in width and hammer. Be carefull not to break the staff bead as it can be used again if you are only aiming to replace the sash cords. It will be attached with anything from panel pins to planking nails. I have come across screws in the past but they are almost always visable on the surface if this is the case. Before actually putting hammer to chisel grab a stanley knife and cut between the staff bead and frame of the box. This will reduce damage to decoration, stop the box being damaged and significantly increase the chances of keeping the staff bead in one piece.
Now removed you have clear access to the lower sash. You will need to cut the cords if not already broken. If the cords are still in place open the sash – does the sash stay in place and appear well balanced? If not make a mental note as it will become important in a later stage of the job. Sometimes the lower sash is tight within the frame. Don’t just try to pull the sash out from one side. Instead lift and swivel the sash at the same time. Without doubt this is the best method to remove sashes which are tight coming outwards.
Cut the parting bead seal with the frame using a stanley knife in the same way you cut the staff bead seal to the frame. The only slight difference being the angle you aim the stanley knife. This is because the parting bead is inserted 10mm or so into a groove. Once cut neatly get the same chisel used to prize the staff bead. Place the chisel low on the parting bead near the sill. Aim between the gap where inserted and the parting bead itself. It’s important to aim in towards the frame or you will break the parting bead and will result in needing replacement.
At this point you have access to the weights. Remove the pockets either side and take out the lower sash weights. Take the old cords out of them and give them a dust off. Make sure you place them next to each other as to not confuse where they will be replaced. This is assuming they were the correct weight as checked earlier in the process. Now cut the cords to the top sash checking beforehand they are well balanced. If this is not the case for either sash then you will need to weigh the sashes using bathroom scales. Then weigh the weights. Work out what add weight is required and add accordingly. So an example might be the sash weighed 20lbs. The weights weighed 16lbs combined. You need 4lbs of add weight. You will add 2lbs of make weight each side. Make weights are most commonly sold in 1/2lb and 1lb increments. Place these make weights next to the weight they need to be added to.
You then need something to thread the sash cord through the box. We use something known as a ‘mouse’. a thin piece of lead connected to a thin section of string works nicely for this job. Now attach the sash cord to the thin string and thread through a top sash pulley. Pull the cord through the weight cavity. Attach the weight to the cord. now pull the weight back up into the frame and to the top of the box. Pin the cord at the pulley so its trapped and cannot move holding the weight at the top of the box. Cut the cord in the middle of the pocket. Repeat this process for the other top sash pulley. Now do this for the bottom sash pulleys. It is always worth attaching top sash weights first as they can sometimes get in the way if done the other way round.
Now place the top sash in the frame and attach to the cords using annular rings. 25mm length is the best as will not cause a problem with the glass generally although always be carefull. Remove the pins that were holding the weights at the top of the box.Your top sash will now function nicely. At this point install the parting bead using 40mm panel pins to hold in place. Fit the bottom sash to the lower sash cords in the same way as the top sash. Now place the staff bead where you initially removed it from.
That’s it – you have changed your sash cords and can expect 10-15 years of trouble free use!