Sash windows, repair don't replace!

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Feltwell
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Location: Shropshire, England

Sash windows, repair don't replace!

Post by Feltwell » Wed 10th Jun, 2020 9:59 pm

Quite a while ago - really quite a while ago - I said I'd do a post on the basics of sash window repair & improvement, to hopefully encourage anyone who's looking at their windows and doubting their abilities that a sash window is perfectly repairable by an enthusiastic amateur - and that those windows can look good & work well afterwards! Sash windows do not have to be heavy, awkward things to open that rattle in high winds and let drafts in! You certainly don't need to replace them to get a window that works smoothly and keeps the drafts out.

This post is definitely not intended to be a masterclass in sash window repair - that's the whole point, I'm no expert, I'm certainly not a time served carpenter, but I've managed to successfully repair and significantly improve the usability of my windows and significantly extend their life.

There are different ways to repair them - this is just my way of doing it. This post is aimed at the beginner, so for those with knowledge already please don't think I'm being patronising. I did a previous post showing much more extensive repairs to a bay window which seemed to go down well, but I didn't really say anything about how to strip and rebuild the window, that a beginner would need to know.

viewtopic.php?f=1&t=16118&p=219935&hilit=bay#p219935

So, what's our patient? It's a Victorian 2 over 1 box sash window, made in 1899 and heavily neglected since. Why "2 over 1"? Just the number of glass panes, 2 on the top and 1 on the bottom. It's one of the first floor windows on this old picture. Why is it a "box sash"? The weights in the frame (that counterbalance the weight of the window) travel up and down in a "box" within the frame. This is a very typical window for it's period, the box being hidden, mounted behind the facing brickwork of the house.

Image

The good news is, sash windows can be renovated entirely from the inside. Stripping the old paint off is a bit easier if you can access from the outside, but it can all be done from the inside.

So this window is in fairly typical condition. It looks rough from the outside, much of the putty holding the glass in is missing and the paint is peeling. The top sash has been painted shut, the bottom sash is difficult to open, rattles in the wind and lets a draft in.

First thing, be prepared to board your window up at the end of the day - especially if you are redecorating it, you won't get this job done in a single day. Have a piece of OSB or cheap ply cut to size and ready to use.

Next, a tool that is both cheap and I think invaluable for this job and many others that I strongly suggest you treat yourself to - a small pry bar with a curved blade on one end, like this:-

https://www.screwfix.com/p/magnusson-pry-bar-8/8640v

Even better, get a set of bars, you'll use them! https://www.screwfix.com/p/magnusson-ba ... eces/5341v

First job is to remove the "staff beads", which hold the bottom sash in place. They will normally be nailed in place and stuck with paint. Use the blade on the small pry bar, start in the middle on the uprights and hammer it along the joint to break the paint line - then hammer against the curved part of the bead towards the middle of the window - once it starts to move they usually come off quite easily. Don't worry if you damage or break them, you'll be replacing them anyway. Try not to lever against the frame. All 4 beads come out as they all get changed.

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The bottom sash is now able to swing into the room on it's cords.

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The cords are simply nailed in grooves in the sides of the sash - you'll be replacing them so you can carefully cut them - easiest done with an assistant, get them to cut them close to the sash and tie a knot in the end before carefully letting the cord go back over the pulley, lowering the weight gently until the knot jams in the pulley.

Next up is removing the "parting beads" - which keep the 2 sliding sashes apart - and the top sash.

Image

But first off, a word of caution.

The top sash is often painted shut, if yours is and you're not careful it can suddenly release and come down like a guillotine and injure you. Why? Well, people had a habit of just nailing the sash shut if the cords broke, and those nails may well have rusted through and it's just the paint holding it in place. Or, someone many years ago may have carelessly decorated and painted it shut in position, then either the sash cords have rotted later (original ones were just made of cotton rope) and the weights have dropped, or - as has happened to me - as soon as you disturb the window the cords break, sending the weights crashing to the bottom of the box! Fortunately with the window shut the weights are near the bottom anyway, so don't have far to fall.

So, I strongly recommend you prop it up with an appropriate size bit of wood or even better use 2 clamps if you have some long enough and that can be reversed to be used as a spreader.

Image

You don't need the scaffold tower! I had it there for other jobs, it is a help with this but not essential at all.

Next thing is to get the parting beads out. You will almost certainly break them, they are getting replaced so don't worry. Using your trusty little pry bar, gently tap the curved blade in between the parting beads and the top sash all the way along on both sides to break the paint line.

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The bead just sits in a groove in the frame and pulls out - it may have been nailed in as well - and you may need to work along the edge on both sides with your pry bar blade and a hammer and break the paint line to free it.

Image

Run a small chisel along the bottom of the groove to remove any stuck remnants, never try to lever them out from the sides, you'll just cause damage.

Next thing is to ascertain if the top sash is free - if you're lucky, or if it wasn't painted shut to begin with, it will just swing in and can be removed in the same way as the bottom sash.

If it's stuck, first thing is to find out if it's been nailed shut. *Usually* if someone has done this they will have nailed through the "horns":-

Image

You may be able to see the nails - you can in my picture above, someone nailed under the horn rather than through it, which is rare and helpful! You may be able to pass something thin (like a steel ruler) behind the horn to feel if there is any obstruction, you may need to take the paint off the horn with a heat gun to see. The easiest and least damaging way to deal with nails, especially if they've been hammered with heads flush or recessed, is to use an oscillating multi-tool (like this https://www.screwfix.com/p/erbauer-emt3 ... 240v/622fx) with a metal cutting blade to slip behind the horn and cut through the nail - but if that's not possible you'll need to resort to whatever means necessary, accept that using pliers or the pry bar head will cause a little damage to the horn that will need filling later.

If you've dealt with the nails or there weren't any and it's still stuck, it's most likely just the paint around the perimeter on the outside that's holding it in. A bit of gentle "persuasion" pulling it into the room usually does the trick. If not you'll have to go round the outside edge with your pry bar blade and a hammer and break the paint line - this is when an assistant to hold the sash, and sometimes the ability to get to the outside rather than trying to reach up from the inside & below, makes life easier.

You've now got both sashes and all the beads out, next job is to remove the "pocket covers". These are bits of wood in the side of the frame, low down, that give access to the weights - the parting bead groove runs down the middle of them. You should be able to see their outline in the paint, if not you may need to strip the paint off. You can see the bottom of the cover at the top of this picture, about 6" up from the cill, with a screw driven into it.

Image

Go round the outside of the cover with your trusty pry bar blade and hammer and break the paint line. There should be nothing other than friction holding the cover in, but just have a look over it first to check, sometimes there is a screw at the bottom. Do *not* try to lever it out at the edge - you'll often notice damage where some numpty has done this in the past! The cover comes out bottom edge first, the top is shaped and held in place. I find the best way to get it out with no damage is to drive a screw into the bottom of the parting bead groove about an inch up from the bottom of the cover, as in the picture above - then lever it out using a larger pry bar, against a bit of scrap wood on the frame below.

Image

Now the sash pocket is out, you can untie the knot in the sash cord and remove the weights - and that is the disassembly stage done. The next "thrilling instalment" will be the repairs and the start of reassembly...……..

CliffordPope
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Re: Sash windows, repair don't replace!

Post by CliffordPope » Thu 11th Jun, 2020 10:33 am

An important difference to note is that you are decribing the kind that have the mechanism recessed in the brickwork, so there seems to be minimal wooden beading round the edges facing the outer wall.
Ours has the mechanism entirely encased in a wooden box inserted into the window opening from the outside, so there is a wooden covering board about 4 inches wide along two sides and along the top.
The essential mechanism and construction is as described, but it is a lot easier gaining access from outside. It feels very precarious sitting on the window ledge with legs dangling inside whilst replacing these boards or even simply painting them.

Feltwell
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Re: Sash windows, repair don't replace!

Post by Feltwell » Thu 11th Jun, 2020 10:52 am

Absolutely - I believe the one I've shown is the most common type, for your typical Victorian brick-built house especially, but there will be variations out there, either regional or to suit the construction of the walls, especially if they're not brick. Horizontal sashes were used in some parts of the country!

Of course the other variation is these windows will nearly all have been constructed in local small joinery shops rather than en-masse in a modern factory, so there's bound to be some small variations that only certain joiner's practised.

Surveyorman
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Re: Sash windows, repair don't replace!

Post by Surveyorman » Thu 11th Jun, 2020 6:23 pm

Great post Feltwell and lovely images to go with it. My friend does this professionally around West London and he’ll love reading your post on this. Top job! :D

overlander matt
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Re: Sash windows, repair don't replace!

Post by overlander matt » Thu 11th Jun, 2020 10:29 pm

Really good post Feltwell. Thank you for taking the time and effort to pass on the knowledge!

I believe there was a building act in 1774 that stipulated the boxes needed to be recessed behind the brickwork. That date has helped us estimate the age of various parts of our home.

CliffordPope
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Re: Sash windows, repair don't replace!

Post by CliffordPope » Fri 12th Jun, 2020 8:26 am

overlander matt wrote:
Thu 11th Jun, 2020 10:29 pm


I believe there was a building act in 1774 that stipulated the boxes needed to be recessed behind the brickwork. That date has helped us estimate the age of various parts of our home.
It didn't apply to farmhouses in west Wales then. Ours was built in 1875.

monkeyhead
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Re: Sash windows, repair don't replace!

Post by monkeyhead » Fri 12th Jun, 2020 11:27 am

What a great and helpful post - thanks for putting up here.

We have another cottage dating back to the 1870s with two surviving sliding sash windows. One had rotted so badly and the window frame broke, so I had it replaced by a local joiner. He did a great job on it, and it works really well now. The second will need attention at some point and is as rough as you describe. I may have a go at doing it myself now based on this - if I have the time!

Looking forward to seeing the putting back together post!

Gothichome
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Re: Sash windows, repair don't replace!

Post by Gothichome » Sat 13th Jun, 2020 12:52 pm

Feltwell, the construction of your windows are exactly the same as the windows in Gothichome but for one small difference, the access door to the window pockets have a V notch at the bottom that the door sits in and a single screw at the top holding it in place. I also see the same areas of rot at the corners, my repairs are are the same as yours, although, my saw lines are not nearly as pretty as yours and the filler not nearly as tight. Are you using a rotary reciprocating saw, if so I think I may need more practice with mine?

MatthewC
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Re: Sash windows, repair don't replace!

Post by MatthewC » Sat 13th Jun, 2020 4:53 pm

This is an amazing resource - well done Feltwell!

One thing I would add, re your remarks about the top sash possibly being able to do you damage: I have found three windows here which were never set up with an opening top sash - they had no pulley, no weight, no cord and in fact not even a hole for a pulley. I think all had been nailed at 45 deg at the bottom and those nails had corroded away. The first one surprised me, but happily I realised as I was freeing the paint and was able to wedge it in place. After that I was prepared!

Well done

Matthew

Feltwell
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Re: Sash windows, repair don't replace!

Post by Feltwell » Sat 13th Jun, 2020 10:38 pm

Thank you everyone for the positive feedback! Sorry for the delay in posting, I've been raking out old mortar in readiness for repointing brickwork all day - a tedious, tiring, filthy job, especially when the original mortar was made with coal dust as one of the ingredients. Sitting down to do this post restores some sanity, before the mammoth whole-house repointing task finally pushes me over the edge!

Anyway - Sash windows! Let's move on to look at the sliding sashes that you've just taken out. You may be lucky and they are in good condition, requiring nothing more than redecorating. Presuming they need some repair though, let's look at your options.

First off, a lot of repair tasks will mean taking the glass out and even with no repairs required there's a fair chance your original putty needs attention, at the bottom of the window especially. If no repairs are needed and most of the putty is solid, you may get away with just patching any loose sections that you've managed to remove.

But let's presume that's not the case and the glass has to come out.

So first job is how to get the "facing" putty - the angled fillet of putty on the outside of the window - off. It may be so bad that it's falling off, but usually even then you'll have loose bits and solid bits. I'm presuming your glass is held in with glazier's putty, which has been around forever and consists of linseed oil and chalk - pretty basic and cheap stuff.

Now I have a confession, I am lucky enough to have a putty lamp, a tool that is ridiculously expensive new but which is great at softening old putty without risking the glass. With many windows to repair I struck gold and managed to get one secondhand from Ebay - from another forum member as it turned out - but they are as rare as hens teeth, so don't count on finding one.

You should always try to save old "wobbly" glass, it's part of the character of the house. But if the glass is broken then you may as well just attack the putty with a heat gun, same sort as you use for paint stripping - heat will soften old hard putty. If you're trying to save the glass though, you can use heat but with extreme caution - I have softened putty successfully with a heat gun, using a piece of aluminium sheet held at 90 degrees to the glass where the putty and glass meet to stop the glass getting hot. Scrape the putty off. I've got loads of paint scrapers, but my favourite by a long way, which I heartily recommend you invest in, is one of these - perfect for getting softened putty off, and perfect with a heat gun for paint removal. Not the cheapest or easiest to find but I rate mine very highly.

https://swedishlinseedpaint.co.uk/Little-Scraper

The other invaluable tool for putty removal is a "hacking knife". It's a blunt knife with a broad back to the blade, you work it along the line between the putty and wood, tapping the back of the blade with a hammer - so your blows are always parallel to the face of the glass. Here's one, but you can get them on Ebay for less than £10, they're all much the same.

https://www.reddiseals.com/product/hacking-knife/

Note that within the putty you'll come across "glazing sprigs" - little triangles of steel pushed in to the wood to hold the glass in whilst the putty goes off - or they may just have used small nails. Pull them out with pliers.

Once your glass is out, the bedding putty beneath can be taken out with the aid of a heat gun and scraper, in fact at this point I usually strip all the paint off the whole sash.

Repairs necessary to the timber will obviously vary hugely. I find the bottom rail of the top sash is the most vulnerable and likely to be decayed, especially if the putty was shot.

If you've just got loose joints to repair - which tends to be at the bottom of either sash - I just pull the joint apart ever-so-slightly, put a bit of glue in and clamp back together and leave it overnight. Personally, I like this glue, Titebond III :-

https://titebond.co.uk/products/titebon ... 7652132963

I find it works well and is easy to clean up, but glues are definitely an area where many woodworkers have a personal preference. I've also used the foaming polyurethane glues before to good effect, but they are a bit messier.

A couple of long clamps are needed, I've got old fashioned sash cramps which work well, but the one-handed type clamps are very easy to use and can be used as spreaders to hold the top sash up, as I described above.

https://www.toolstation.com/irwin-quick ... amp/p46258

If your sash is in more of a state, you may need to replace some sections. Pretty much every town still has small local joinery shops, making timber doors, windows & shop fittings - they're invaluable, get to know yours! If you're not confident in your woodworking abilities, take your sash to them and have a chat with them - they may say they can repair it, they may say you're better off replacing it, but they can copy your old one. It's always good to retain as much originality as possible but it may be quicker and more economic for them to make a new one, but you definitely want to make sure they can copy the edge profiles on the original.

Another option, if you've a bit more confidence in your abilities, is to get them to cut a new blank rail for you to fit. Joinery shops are invaluable as a source of hardwood, which the DIY sheds just do not sell, other than in small mouldings or strips. Every joinery shop has an offcut store! You're replacing a section that has rotted, to my mind it makes no sense to use modern softwood, you want something more durable - a hardwood or Douglas Fir. The joiner will advise if what he has is suitable.

Here's an example of mine. The bottom rail of this top sash was completely rotten, well and truly beyond salvation. On cutting it back I also found the bottom of the central glazing bar and the bottom of one side rail had gone - this is by far the worst sash I've found here so far. With the old bottom rail out, I was left with this.

Image
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You can see the original bottom rail, the green piece in the middle of this picture:-

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I took that to the joinery shop, found a suitable piece of oak in the offcut store, and they cut it to shape for me as a blank, which you can see in the picture above. I could have done it myself, but they charge so little and it's so quick for them to do, it makes life easier. I had some other hardwood already for the side rail - I cut the horn shape into it, cut a mortice and tenon joint to go onto the new bottom rail, and jointed it to the remaining original side rail with glue and 2 beech dowels. These dowels are invaluable I find - made of compressed beech, drill holes in both sides of what you're joining, they swell when glued in with PVA adhesive (like the Titebond) and give a really strong bond. There are many joints that could be used but this way is simple & effective I believe.

https://www.screwfix.com/p/easyfix-wood ... pack/5587t

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I used a dowel as well to secure the new glazing bar piece to the original remains, and to the new bottom rail. This small piece was a pain to make - I didn't have a router cutter of the right profile. Spot the joint! Original glazing bar above is softwood, new bottom 6" is oak. Victorian softwood was much better than what you commonly get now.

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Why are there black spots on the oak bottom rail? I was working outside, it rained, and I put a steel ruler on the wet oak - this leaves tannin marks that don't come out. Years ago I sold timber worktops, it's why you should never put a wet cast iron pan on an oak worktop, I forgot that :roll: . No harm here though, it's getting painted.

Finally, here's it being clamped up after being glued - note the bits of scrap wood clamped across the central glazing bar to keep the joint in line.

Image

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It turned out well but did take some time.

Next installment, frame repairs...…..
Last edited by Feltwell on Sun 14th Jun, 2020 9:43 am, edited 1 time in total.

Craig89
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Re: Sash windows, repair don't replace!

Post by Craig89 » Sun 14th Jun, 2020 6:56 am

Fantastic post Feltwell. Thanks very much for taking the time to do this. It will be a very useful resource, your knowledge certainly helped me when I worked on my own bay window

Feltwell
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Re: Sash windows, repair don't replace!

Post by Feltwell » Sun 14th Jun, 2020 8:58 am

Thank you Craig!

For anyone looking at the above post and thinking "God that looks difficult" - first off, it's really not, but secondly don't forget the point about using a joinery shop to do it for you or make you a new one - it will still cost a *lot* less than a complete new window. I did that with my bay window - the small side sashes weren't original, they were badly made, fitted badly and were rotten, definitely not worth saving. I could have made new sashes myself but it was just quicker and easier to get the joinery shop to make new ones for me in hardwood. Now they're in and painted up you'd never know they weren't original, and they weren't that expensive.

The other point to bear in mind is the above is by far the worst one I've found here - despite looking terrible, underneath the missing putty and flaky paint the rest have been in remarkably good condition. If you're in doubt how bad yours are go round poking into them with a bradawl, you'll soon get a feel for what is good and bad timber, any rotten bits the bradawl will disappear into with ease!
Gothichome wrote:
Sat 13th Jun, 2020 12:52 pm
Feltwell, the construction of your windows are exactly the same as the windows in Gothichome but for one small difference, the access door to the window pockets have a V notch at the bottom that the door sits in and a single screw at the top holding it in place. I also see the same areas of rot at the corners, my repairs are are the same as yours, although, my saw lines are not nearly as pretty as yours and the filler not nearly as tight. Are you using a rotary reciprocating saw, if so I think I may need more practice with mine?
Interesting that they're pretty much the same, given how far away you are! (Gothichome is in Canada).

Not sure if this is what you mean by a "rotary reciprocating saw"?

https://www.makitauk.com/product/dtm51z

That's what I use - fantastic bit of kit, wouldn't be without one know, for cutting in-situ nothing is better. I find the trick to get good straight cuts, other than the obvious of marking up well, is to do them with one of these round blades first:-

https://www.screwfix.com/p/bosch-wood-m ... 95mm/39314

They are much easier to cut a straight line with than the other types. Often you can't get enough depth though, so I cut with one of those as far as I can and then plunge cut with a straight blade afterwards.

I've just used one of these for the first time as well, seems to be a good bit of kit.

https://www.screwfix.com/p/bosch-wood-p ... 65mm/6920v

Gothichome
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Re: Sash windows, repair don't replace!

Post by Gothichome » Sun 14th Jun, 2020 1:04 pm

Yes, I was searching My brain for the proper term but it eluded me so came with with rotary reciprocating, the word I was searching for was oscillating saw. Some times the brain works, other times not so well. :lol:
A lot of colonial migration (post French colonization) to this area was from Great Briton so a lot of the skills and methods followed. I believe our window assemblies were manufactured at a mill shop or factory not built on site so the design would be pretty standard. I just discovered some of our hardware was manufactured in Briton, it has the old British diamond registration marks in the castings.
Just finished up a storm window repair using the same wood replacement technique as your sash repair, glued my lap joints with modern construction adhesive. Just got it glazed yesterday.

Feltwell
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Re: Sash windows, repair don't replace!

Post by Feltwell » Sun 14th Jun, 2020 2:04 pm

Always good to get a job done. I've seen joinery in America that looks very similar to the UK, I guess it was the era of migration and colonisation from the UK to all around the world, and the skills and practices went with the people.

Mind you it did amuse me in America when I saw terms like "Victorian house, built in 1920" - I guess to them it means the style rather than the period in which it was built.

CliffordPope
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Re: Sash windows, repair don't replace!

Post by CliffordPope » Sun 14th Jun, 2020 4:38 pm

Feltwell wrote:
Sun 14th Jun, 2020 2:04 pm


Mind you it did amuse me in America when I saw terms like "Victorian house, built in 1920" - I guess to them it means the style rather than the period in which it was built.
Ebay is full of that sort of thing. Look up something like "Victorian brass fittings" or "Victorian lampshades" and you will hundreds of items and I bet not a single one of them is Victorian.
And "brass" of course just means a superficial plating of something that looks brass colour over a steel or alloy casting.

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