Sash window needs repair
Image by Scays via Flickr

I have received so many calls and requests for more info on repairing sash windows, so I have put together some notes and hints. So take its a just that, a help, go find a sash window and look at it, make notes see where and how they work, before you attempt any repairs.

Most sash windows of this period follow a standard pattern, of the weight box, with two weights, usually cast iron sausage like rods with a hook at the top, central guide,inner architrave or bead, sash cords and the two windows, with the sash pulleys, in the sash box you will find a small panel to allow access to the weights. that’s it really apart from the upper and lower windows, and main cill.

To get at the windows look at the inside and find a bead holding the inner window in place, this is usually tacked in place, and a good chisel with a little leverage will peal this away, take care and try not to crack or snap, work from the middle, out, its only really necessary to take out the verticals but I find that taking all of it away, cleaning down, is best.

Now look at the sash cord, are they still there, if they are, and still in good nick, pin them both  to the weight box (both sides) just below the pully and ease the lower window back into the room. at the side of the window the sash cord is connected, now there are many ways this might have been done from a metal plate to a nail, mostly there was a small grove for the sash to fit into, try and release,

Next the upper window is ready, lower down and look at both weight box’s you will see a box wood slider rail, this is pinned into a rebate, and should pull out, but experience tells me that this is often so caked with paint its and a little difficult. but it will come out, I have used a number of ways, and the best is to use a clamp with a couple of pieces of wood, either side and gently ease it out, check the head, sometimes there was a rail along the top to, this might have to come out first. I have scored the joint before now to break the paint.

Once the rail has been removed, remove the upper window back into the room, taking care of the sash cord.

Now ease the sash cord free and lower the weights back down, if the sash cords are rotten or missing the weights will already be at the bottom of the weight box.

Now look for a small panel in the two side cheeks, they might be screwed into place or have a catch, On very cheap sash windows the weights were built in, unless the weight box is rotten or damaged, I might be tempted to create a new access rather than strip the window any more.

Have a look at the pulleys, they were usually brass, and often get worn, I found a little chap local to me last time I had this done and they were still available,

Next replace the sash cords, even if they are looking good, the cost is so little and you might as well have it done. Removing the weights from the box via the inspection hatch, take your time they will come out, they went in this way. Thread the new sash cord in from the top, leave plenty of slack, tie to the weight, and pull back in.

On an existing timber window unless it was specifically designed for the new spiral sash window replacement dampers, do not fit them, use the weights.

Now the window, did it slide easily when in place, did it have a lot of play, you might have to add a small liner to the window to take up the slack, or even think of adding a rubber seal, I am a purist in this sense and don’t like mucking about with them, they are a sod to fit properly and often spring free, spend the time fitting the window accurately is my feeling. Try using a hard wood, the windows will slide better, I have seen boxwood used here it’s harder and slides better. Also talc is good, do not use candle wax, I found this to jam windows rather than ease the sliding.

Next look at the main weight box, cill and head, are they ok, the cill might be rotten, so replace, this is not an easy job, and from memory, I had to take out the whole window, and will require some additional help, look at the side cheeks against the brickwork, do not put mortar into any space, clean and see if the window needs to be eased back , if you have to, seal with silicon, but I like to make a proper job of it and make sure its well seated, it lasted this long with out silicon. but hopefully it’s ok, clean down, and get rid of the century of paint I know is there.

Now your into fitting the windows see what the joint is like at the transom, or central meeting point, what sort of fitting was there, they used to be mostly a brass twisting coupler, that as it turned into the female section pulled then together, this is fine, but security is a little lax, best to fit a new screw bolt to either side, have a look about there are loads on the market.

I have had to replace windows before now and rather than make good an old one I had one made, cost a little more but easier. If your a carpenter, this might be an option, use the original glass, new glass looks different.

Replace as you took down, replace any cracked or damaged architraves, I found that supporting the weights with a small stick of wood helps when re stringing, and fitting the sash cord to the window.

Its been a few years since I last did this, I now tend to draw the window and a specialist sash window company comes and does the job, they are expensive and time seems to none existent to these guys, so good on you for attempting it, I seem to remember that it took me the best part of a week to do one window so I think I had a piece of ply fitted from the outside and battened internally to give some security and weather proofing. Best advise, don’t rush, learn as you go, make notes, take photos.

I have reproduced the drawing as a pdf, its there to help, and I can take no responsibility for it not being accurate for your job, Its also for a double glazed window so bear that in mind. I pulled this together for a job I have just completed, to help the local contractor, as far as I know it worked well, but again its just a guide. If you want a pdf copy go to the contacts and send me an email or try skype.

Again these notes are there to help you understand some of the principles of a sash window, there are many variations, sizes, even tripple sash’s, stone cills, brick cill, and combination of both, I can take no responsibility for your project. Print out the notes, add sketch’s ,photos and examples, look at the condition of older examples, how have they faired over the years.

I can see at least 2 hours CPD here, if you make notes and visit old and new examples, whats the difference between weights and the new sash dampers, cill details do they work, Older windows sat behind a skin of brickwork, and sometimes had timber folding curtains built into the jamb, very common in more up market housing of the period, and should in my humble opinion be looked at again.

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Source: Konstrukshon CPD Weblog – Architectural Technologist – Repairing a sash window
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