Re-cording sash windows

[dandrew]

Morning All,

I am midway through the renovation of a mid Victorian (1867-ish) sliding sash window, having dissembled the the beads and pocket pieces and removed the sashes, which have now been repaired and re-painted. I'm thinking about the re-hanging process and have procured the requisite sash cord and made new parting and staff beads, the existing ones being knackered. My chief reference source (Hasluck's Carpentry & Joinery) describes the re-cording process quite well but relies on measuring the existing sash cord (which was too stretched, and therefore non-functional) and nail holes in the sash (of which there are many, some current and some old), which in this case is not helpful. For people who have done this before, how do I measure up the correct length of sash cord so that I only have to hang each sash once, and not go for a trial-and-error process of starting over-long and progressively shortening the cord ?

Thanks, David

 

[Feltwell]

Making your own beads, that's dedication David!

Mark the front of the sashes with where you want the cord to end at the side. Put the top sash as high as it will go, and transfer the mark onto the sash box. Put the bottom sash as low as it will go and do the same.

Thread cord down through the pulleys and tie it to your weights, put the weights in position.

For the top sash lightly tension the cord, so the weight stands up in it's box but does not lift, and grip the cord at the point you marked on the sash box - cut the cord about 3" to 4" shorter than this. Hence the weight will hang 3" to 4" off the bottom of the sash box when the window is closed - should give you enough travel but will allow for a little stretch and the knot on the weight to tighten.

For the bottom sash pull the cord and lift the weights all the way up until they are stopped by the pulley - grip the cord at the point you marked on the sash box - cut the cord about 3" to 4" longer than this and the weight will hang 3" to 4" off the bottom of the pulley when the window is closed.

Avoid traditional waxed cotton sash cord, it just rots and will eventually break - and it stretches. If you want that look then use cotton sash cord with a polyester centre, like this, it will last a lot longer and will eventually look tatty but at least it won't stretch badly and it will take a lot to break it.

https://www.reddiseals.com/product/waxed-cotton-sash-cord/

Or alternatively use pre-stretched nylon cord, which I confess is what I do, and I use Mighton's Grabba - makes cording up sashes a lot easier.

https://www.mightonproducts.com/grabba-pack-of-4

That will last a very long time indeed. For the ultimate longevity you could use sash chain instead of cord, but you'll need new pulleys to do this.

Hope that helps!

 

[MatthewC]

I fully support all that Feltwell says, but would add one thing: don't just re-use the same weights in the same place and expect them to be correct.

I did that and found that, although I had the movement range of the window correct, the bottom one just hung about an inch above the bottom, and the top one was an inch from the top. Two possible reasons for this: (a) they were never correct and (b) the removal of so much paint had a material effect on the balance (which would only affect the bottom one). Either way, it's pretty annoying, so make sure that you balance them properly.

If in doubt (or if the right weight is between two sizes) then you want a little LESS weight on the bottom sash and a little MORE on the top one to avoid this. In my case I just swapped the weights between top and bottom!

Matthew

 

[Feltwell]

Sounds like your sash cords are a little too long Matthew, if I'm reading that right?

It's quite common for the weights to be out - usually because the glass has been replaced at some point and it's a slightly different thickness to the original. I tend to work on the weights for the top sash being (combined) 1/2 to 1 lb heavier than the top sash, and the weights for the bottom sash being 1/2 to 1lb lighter than the bottom sash - as you say, so the window will pull shut tightly. Having said that, with brush seal draughtproofing fitted (which I highly recommend) the friction of the seals means it's not that critical. What is critical is to have an equal weight either side.

Bathroom scales are accurate enough to work out what weights are required. If weights are under you can buy "make weights" from Reddiseals or Mightons, small extra round weights to thread down the cord and sit above above your existing weights.

 

[Lime]

A word of warning if using synthetic cord.
The type of knot (two half hitches) commonly made to attach weights when using original sash cord of natural fibres is likely to slip undone in use with synthetic cord.

 

[Keith Bowman]

A word of warning if using synthetic cord.
The type of knot (two half hitches) commonly made to attach weights when using original sash cord of natural fibres is likely to slip undone in use with synthetic cord.

Time to learn how to tie a bowline in the dark?

 

[fernicarry]

I used Mighton's Grippa's, similar to the Grabba's, after Feltwell pointed me in that direction. If you cut the cord a little on the long side you can pull it through the grippa afterwards to get it just right. It made rehanging a very straightforward one-man job.

Also simplifies future dismantling which is essential IMO but then I'm more of a 'tinkerer' than a 'finisher' so have a bit of an aversion to things that can't be easily taken apart for adjustment.

 

[MatthewC]

Sounds like your sash cords are a little too long Matthew, if I'm reading that right?

It's quite common for the weights to be out - usually because the glass has been replaced at some point and it's a slightly different thickness to the original. I tend to work on the weights for the top sash being (combined) 1/2 to 1 lb heavier than the top sash, and the weights for the bottom sash being 1/2 to 1lb lighter than the bottom sash - as you say, so the window will pull shut tightly. Having said that, with brush seal draughtproofing fitted (which I highly recommend) the friction of the seals means it's not that critical. What is critical is to have an equal weight either side.

Bathroom scales are accurate enough to work out what weights are required. If weights are under you can buy "make weights" from Reddiseals or Mightons, small extra round weights to thread down the cord and sit above above your existing weights.

No, the cord wasn't too long, but the weights on the bottom sash were just that little bit too heavy, even though I re-used the originals in the same place. To have that effect any replacement glass would have to have been lighter than original, which I would find surprising. Perhaps it was just my removal of all the old paint which made the bottom sash lighter? I know I took a lot off but I am surprised it made that much difference!

The upper sash may have been wrong for years, as I had to free that one from all the paint. Everything was all fixed when I swapped the weights around (without changing the cord lengths), so possibly the weights had been moved before, incorrectly.

 

[Feltwell]

The upper sash may have been wrong for years, as I had to free that one from all the paint. Everything was all fixed when I swapped the weights around (without changing the cord lengths), so possibly the weights had been moved before, incorrectly.

I've found quite a random selection of weights here, I've had to be choosy and/or get the angle grinder out / add make weights. I found a stash of spares in the cellar which have been useful. I too would be surprised if paint removal had made much difference to the overall weight, maybe they were just always wrong?

Freeing up stuck sashes is very satisfying, when I moved in here every single top sash was painted shut - some nailed shut as well, but most just held by the paint. However, in getting them free, in most cases I get a horrible sound as the rotten old cotton sash cords snap after being disturbed and the weight plunges to the bottom of the sash box! The only ones where that doesn't happen are where the cords had already snapped! Fortunately no damage, before I learnt to remove the pocket cover and stuff a bit of rag into the sash box first before attempting to free the top sash.