transom sash windows

How to Replace Sash Window Springs

A sash window is the second most popular type of window after casement windows. They consist of a fixed panel, and a mobile ‘sash’ panel, which is capable of sliding up and down to allow the window to open and close. This is possible thanks to a complex arrangement of cords, weights and springs, that are concealed into the frame.

Since these mechanisms are concealed, they tend to boast a long lifespan. When they do fail however, it can be tricky to correct the problem and get the window functioning again – but not impossible.

Here we’ll walk you through how to remove and replace one of these components: the sliding sash window springs.

What Do Sash Window Springs Do?

Traditional sash windows operate via a system of weights and pulleys that keep the sash in position. Weights are carefully chosen to balance against the sash, so that when you open the window, you don’t have to actually bear all of the weight by yourself.

Of course, this vastly increased the weight of the window. While you can still get weight-and-pulley sash windows, modern alternatives use springs instead. This means that instead of the weight of the sash being counterbalanced by the weights in the frame, it’s counterbalanced by a set of springs, each attached to the pulley just as a weight might be.

A spring-based sash window will come with one spring on each side, with the pair balancing the weight of the sash between them. When one of the springs fails, your window will fall down on one side, and won’t stay open. Now, it might be that it’s the cord attached to the spring that’s snapped rather than the spring itself. The only way to find out is to open up the window and check.

How to Replace Sash Window Springs

You won’t need any specialised tools to do this job, though you will need:

  • A flat-head screwdriver
  • A new sash window spring
  • Someone to help you.

Let’s run through the process, step by step.

Step 1.

You need to remove any stops that might be preventing your sashes from rising too far within the frame. These are usually plastic, and removable with just a bit of force. You’ll find them on the inside, near the top of the window.

Step 2.

Next, you’re going to pull out the clips, which you’ll find a few inches above the sash. These clips are designed to keep the weights in place while the window is complete. You might need to prise these away with the head of your screwdriver. You don’t want to remove them completely; you just need enough room to lift the sashes.

Step 3.

You’re now going to remove the sash from the frame. If it’s a large sash, then make sure your volunteer has hold of the other end. You’re going to be lifting it up on one side, following which the other should slide out easily. Lay the sash on the floor, somewhere safe.

Step 4.

You’ll be able to see the spring balances now. Push on the top of them to release the clips, and keep hold of the springs to prevent them relaxing. Lift up the spring balance until there’s no more tension on it, and you’re able to easily unhook it from the bottom of the frame. Don’t release it under tension, or you’ll risk injuring yourself and damaging the window.

Step 5.

Having removed the balance, it’s time to measure up for a replacement. To do this, measure the width across the back of the balance, and the height of the channel (not including any attachments at the top or bottom of the channel). You’ll need to match those attachments up when you’re shopping for a replacement channel.

Step 6.

If you don’t already have a replacement spring balance, you’re going to need to purchase one. It’s fine to leave the window without a spring during this time; you just won’t be able to open it.

Step 7.

Once you have your replacement spring to hand, you’re going to be attaching it using the hook at the bottom. There should be a gap at the bottom of the frame that’ll accommodate it. To get the balance into the frame, you’ll need to push down until you can get the top of the balance underneath the screw. Once this is done, you’ll have a new spring inside the frame, and all that’s left will be to replace the sash itself.

Step 8.

Getting the sash back in might well be a two person job. You’re going to be lifting the sash right to the top of the frame and pushing the opposite side into positon. You then lower the entire sash until you can feel it moving against the spring balances. You’ll know if you’ve done it right, because the weight of the sash will immediately decrease.

Step 9.

Finally, we’ve got to re-insert the clips so they’re flush with the frame. Do this in exactly the same way as you took them out.

Step 10.

Before we finish, it’s worth checking that everything moves as it should. Be sure to lift and lower the sash entirely, several times. Once this is done, you can safely declare the window fixed.

Now, if all of this seems like a lot of work, we’d recommend you save yourself some time later down the line and replace both springs in one go.

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Coloured wooden windows

What U-Value Should Windows Have?

When you’re shopping for a new set of windows, there’s one metric that you’re almost certain to encounter, and that’s the ‘U’ value. This number is a way of describing a window’s thermal efficiency, but what does it mean? What are the best U-value windows, and what’s the U-value of double glazing?

How Does U-Value Work?

Let’s start with some definitions. A U-value is a measure of heat energy moved through a given area of material in a given period of time. This might be a window, but it might equally be a wall or a door. It’s most often measured in watts per metres squared, when the difference in temperature between the two sides is one-degree Kelvin. Given that that’s a bit of a mouthful, we tend to say ‘W/m2K’ instead.

It’s important to note here that the U-value of a given window refers to its efficiency per square metre. So, two windows might have the same U-Value, but transmit heat at different rates because one is a different size to the other.

The lower its U-value, the better an insulator the window will be. If you’re aiming for the most thermally efficient house possible (as most of us are, cost permitting), you should almost always go for the window of the lowest U-value.

How Do You Calculate the U-Value of a Window?

If you’re buying a new window, you’ll be able to see its U-value advertised by the manufacturer. Unfortunately, calculating a window’s U-value yourself isn’t particularly easy, nor are your calculations likely to be totally accurate. However, if you’re determined to try and calculate the U-value of a window yourself, you can find out how here.

For example, not every glass panel is manufactured to the exact same standards, and what stacks up in a laboratory might not translate into the real world. While there are bodies like the BFRC (which we’ll discuss in a minute) there to maintain quality standards, it’s important to treat claims about efficiency with a degree of scepticism.

Secondly, the glass panel isn’t the only thing you need to consider – the window frame also conducts heat, and will contribute to the thermal efficiency of the window. While it’s possible to account for this in your calculation, given that the interior of a window frame is made from a range of different materials, doing so can be very difficult.

To comply with building regulations, windows (like every other element of your property) must meet a certain minimum U-value. In the case of a window, it’s 1.6 W/m2K. Double-glazed windows, filled with argon, are typically 1.4 W/m2K, while thicker triple-glazed windows can go as low as 0.7 W/m2K.

The British Fenestration Rating Council provide a colour-coded rating system to help homeowners distinguish between different qualities of window. Good windows which keep the heat in are rated A or above. Bad ones are related E or below. While this rating system is easy to follow, and will prevent buyers from making a mistake they’ll regret for years, it isn’t quite as specific as the U-value. As such, when you’re shopping, we’d suggest looking for the U-value and spending your money accordingly.

For example, Jeld Wen’s triple-glazed ‘Stormsure Energy+’ series of casement windows can have a U-value of 0.8, 0.9 or 1.0, depending on which options you select. Each window in the range, however, comes with the same BFRC rating of A+. So, if you want the absolute maximum thermal performance available, you’ll need to look beyond the lettered rating, and at the U-value.

U-Value: Double Glazing versus Triple Glazing

Given how effective double-glazing is compared to single-paned glass, you might suspect that adding an extra layer would improve things still further – and you’d be right. Triple-glazed windows are more effective insulators than their double-glazed counterparts.

That said, there are a few drawbacks to consider. Triple-glazed windows tend to be thicker, which means they’re not ideal for use in smaller frames. They’re also more difficult to manufacture, and as a result, more expensive.

Putting to one side practical considerations like these, there are a few instances where a triple-glazed window might not be as good a choice as its U-value might suggest. This is because of heat gain, or a lack of it.

As sunlight pours down onto your triple-glazed window, the heat won’t reach the interior as quickly as it might if the window were double-glazed. As such, south-facing windows which receive direct sunlight might be better suited to double-glazing than triple-glazing.

In Nordic countries where triple-glazing is widespread, there’s less sunlight, and so this issue isn’t as pressing. In the UK, it’s worth treating triple-glazing with a bit more caution. We’ve examined the thorny double-versus-triple-glazing debate in greater depth in a previous article, and if you’re considering going for triple-glazing, we’d suggest that you give it a read.

While U-value isn’t the only metric of a good window, it’s one worth paying attention to before you make your purchase. Generally speaking, the lower the U-value, the better. It’s worth investing more in a superior-quality window, as the extra cost is likely to pay for itself over the lifetime of the glazing. That said, thermal efficiency isn’t everything – if you’re not happy with the look of the window, or the warranty isn’t sufficiently long, then going for a super-efficient U-rating at all costs probably isn’t a sensible strategy.

Ready to shop for new windows? Take your pick from our JELD-WEN range, timber range and aluminium range. You can also get an estimated quote here.

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sash bay window

The Pros and Cons of Sash Windows

Sash windows are the second most popular variety of window in modern Britain, being beaten only by outward-opening casement windows. They enjoyed massive popularity in Victorian England, which means they’re a natural match for period properties.

But are sash windows any good today?

The answer is a qualified yes, but there are some pros and cons to consider.

Benefit of Sash Windows: They Look Good

There’s nothing quite like a sash window when it comes to appearances. They can add a traditional touch that’ll elevate certain properties, and pay for themselves by adding value to the building.

At the same time, the sash window is relatively versatile, considering its traditional style. Whether it’s a traditional country home or a contemporary apartment, a sash window is almost-guaranteed to please.

Benefit of Sash Windows: They’re Safe & Secure

Sash window security is another reason to prefer them. Given that just one panel can be opened at a time, they’re a lot more difficult to clamber through than casement windows. It’s also easy to incorporate extra safety features like locks and child safety devices.

Benefit of Sash Windows: They’re Low-Maintenance

Like their casement equivalents, aluminium and uPVC sash windows require barely any maintenance. The former are powder-coated at factory level, while the latter are naturally white and not designed to be interfered with at all. You won’t need to sand them, nor apply any coats of varnish (though you might need to occasionally replace the internal cord). There’s also no risk of warping or rot, making a metal or plastic sash window a great choice for windows in hard-to-reach locations.

Sash Window Cons: Poor Ventilation

Saying all this, there are still a few problems with sash windows worth bearing in mind. One of them is ventilation. Given that sash window panels are built to slide behind one another, like sliding doors, you’ll only be able to collapse the glass to the size of a single given panel. This can increase the chance of condensation building up on the inside of the windows.

How much the different benefits and drawbacks of sash windows will matter to you will depend on your priorities and tastes. Most of us will need to decide between casement and sash windows, and if the advantages we’ve listed here appeal to you, you might well choose the latter.

uPVC kitchen windows

A Guide to uPVC Windows

In the UK, the majority of window frames are manufactured using uPVC. uPVC windows offer several distinct advantages over windows made from aluminium or timber, the most obvious of which is their affordability.

In this article, we’re going to take a closer look at uPVC windows, and what they can and can’t do. We’ll do this by addressing a few questions about the limitations of uPVC, and discussing which ones can and can’t be overcome.

What is uPVC?

First, let’s establish exactly what we’re talking about. PVC, or poly-vinyl-chloride, is a form of plastic perhaps best known as a substitute for leather. You might have seen tarpaulins, dresses and coats made from the stuff. In this context, the material has been supplemented by a plasticising agent, which is what allows it to become flexible and stretchy.

That’s not the extent of PVC’s powers, however; if an extra ingredient is added, the material sets in a rigid, tough form. This material is known as unplasticised PVC. It’s particularly suited to use as a building material, and it’s the stuff from which most windows in the UK are now built.

Can uPVC Windows be Painted?

The overwhelming majority of uPVC windows are brilliant white, and those that do come in other colours are given their pigment at factory level, before the plastic has set. uPVC is naturally resistant to paint. Their surface is low-friction, which allows them to resist stains, and rainwater to quickly slide away. For the most part, this is an advantage, as it makes cleaning the windows easy, and it gives the surface of the material a durable, glossy appearance. It also makes painting your uPVC window very difficult.

This doesn’t, however, mean that painting a uPVC window is impossible – It just means that any coat of paint you apply will be more prone to peeling and warping over time, as differences in pressure and temperature gradually lift the paint from the surface of the plastic.

For best results, we’d suggest masking the glass thoroughly and applying a spray-on coat of matte paint. If you want a gloss finish of the sort you’d get on a door, then you’ll need access to a heavy-duty paint-sprayer. If you’re going with a gloss paint and a brush, then you should be prepared to apply multiple coats, and sand-down with extremely-fine sandpaper. Be very careful that you don’t sand all the way down into the plastic; once the top layer has been scraped off, you’ll never get it back.

While painting can be a great way to lend a new lease of life to aging uPVC windows, if you’re investing in new windows and aren’t keen on them being white, we’d strongly suggest opting for engineered timber or aluminium windows instead. The material simply isn’t built to be modified in this way, and looks and functions best when left in its usual glossy-white state.

Can uPVC Windows be Recycled?

One of the reasons that uPVC is so affordable is that it can be easily reshaped and recycled. It’s a thermoplastic polymer, which means it’ll melt when exposed to a sufficiently high heat. uPVC windows should therefore be taken to a recycling facility when they reach the end of their lifespan. Find your local recycling centre, and remove any non-uPVC materials, like seals, and metal hinges, from the window.

How Long Do uPVC Windows Last?

uPVC windows can easily last three decades or more. To be assured of the best possible quality, we’d strongly recommend checking the length of the warranty before deciding. If the supplier isn’t prepared to put their money where their mouth is when it comes to longevity, it’s time to start worrying. Look for a warranty of ten years.

Of course, this is assuming that your installation was carried out by an expert under good conditions. If the window is misaligned or otherwise poorly-installed, you can expect it to fail much sooner.

When failures do occur, it’s usually a part of the window that’s not made from uPVC that’s to blame. For example, moving parts like seals and hinges might wear out and become misaligned thanks to frequent stress and gravity. These hardware components can in most cases be replaced while leaving the window itself intact.

Finally, there’s another factor complicating things here, and that’s the improvement of the technology over time. Given that modern windows are far more efficient than those manufactured even just ten years ago, you might consider it worth your while to swap out for some new ones.

Signs of an aging window

If you think your uPVC windows are looking a little sorry for themselves, then you’ll want to keep an eye out for the following.

Condensation occurs between the panes of a double-glazed window when the seal around the edges has broken, and water vapour has been allowed to creep in. The presence of such a gap means that all of the inert gas inside the panel has escaped, which will hugely reduce the efficiency of the window.

Draughts around the window frame can be fixed without replacing the window, but they’re usually evidence that the window is on its last legs. If you find yourself shivering every time winter rolls around, investing in replacement windows might make financial sense.

Discolouration. uPVC windows are white when they’re first installed, but this can change. Prolonged exposure to ultraviolet light can, over time, cause that white to turn yellow, which, amongst other things, will devalue your property. If your home is equipped with old, yellow windows, then a replacement set is probably long overdue.

Can You Drill into uPVC Windows?

Unlike timber, uPVC is not designed to be modified once set. While it’s possible to do so, there are better alternatives. For example, if you need to drill a hole to pass a cable from the outside of the property, it’s almost always better to drill said hole in the surrounding wall than it is through the window frame itself. The same applies if you’re fitting blinds or curtains to your uPVC windows.

uPVC windows are very rarely uPVC all the way through – they often contain metal cores which can make drilling problematic.

What’s more, sealing the edges of the hole once you’re done will be difficult. You’re more likely to compromise the performance of the window than you are to improve it. A gaping hole in your window frame will look amateurish, particularly when you come to sell the house.

But what if you’re looking to replace your uPVC handles? Won’t that require drilling into the window? No, because uPVC handles are not interchangeable, like their counterparts on timber windows. They’re designed to remain in place for the lifespan of the window.

How Can You Maintain uPVC Windows?

To ensure that your windows enjoy the longest possible lifespan, we’d suggest giving them some occasional TLC. We’ve covered how to clean and refresh them in previous blogs, so be sure to give them your attention.

What’s Wrong With uPVC?

As we’ve mentioned, uPVC compares favourably to timber in terms of how much maintenance it requires, but it’s not a perfect material. Amongst its disadvantages is a tendency to expand during periods of hot weather. In extreme cases, this can exacerbate any existing misalignment issues and make it difficult to shut the window. There are a few things you might do to combat this problem, and we’ve covered a few of them here.

Homes in conservation areas are subject to stricter planning controls, which might make installing uPVC windows impossible. For all of their many virtues, uPVC windows will reliably undermine the impression that you’re walking through a 16th-century countryside village. As such, check with your local authority before you place the order – as having to remove your windows a few days after installing them can be embarrassing, not to mention costly.

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An open casement window

How to Repair a Casement Window

The most popular style of window in the UK is the casement window. Unlike its closest rival, the sash window, the casement window opens by swinging outwards on a set of hinges.

This offers several advantages.

For one, casement windows are less complex and easier to maintain than sash windows, and they can be equipped with compressible seals which keep out draughts and can help cut your energy bills.

However, as resilient as casement windows are, problems can occasionally occur. Thankfully, the majority of those problems can be solved without the need to call in a professional. In this article, we’ll look at how to repair casement windows. We’ll examine some common issues, and see how they should best be addressed.

How do you fix a sagging casement window?

Throughout a casement window’s lifespan, it will gradually sag as a result of gravity, and it only takes a few millimetres of drop for the window to begin catching against the frame. If your window is dragging, you need to adjust the hinge channel to compensate. This should be done from the outside. You’ll need to first establish the direction in which your window is sagging, and then move the corresponding hinge.

Step 1.

First, we’re going to remove the arms that make up the hinge at the bottom of the window. Open it and unscrew everything. You’ll then be able to lift out the sash which tethers it to the window frame.

Step 2.

It’s time to fill in the existing holes. Do this with epoxy resin if your windows are uPVC, or wood-filler if they’re timber. Don’t be tempted to skip this step, as you’ll be drilling new holes just a few millimetres from the old ones, and the drill could slip into the old holes. Be sure to rub the filling smooth for the best possible finish.

Step 3.

Now you’re going to drill some new holes using an 1/8” pilot drill. Drill them a couple of millimetres across from the old holes. A little bit of guesswork may be in order here, given that there’s no way to test the window before you’ve secured it to the frame. If you’ve only just noticed the problem, chances are that moving the hinge across a small increment will result in a significant improvement.

How do you clean casement window hinges?

On the other hand, rust accumulating on your gears can cause the window to become stiff and eventually inoperable. Cleaning the gears thoroughly requires a little bit of disassembly – but it’ll help fend off corrosion and keep your window working as it should for longer.

Step 1.

First, we’re going to unclip the operator arm. This usually comes apart from the window via a clip. It’s attached at the other end via a series of screws, which can be removed with the help of a trusty cross-head.

Step 2.

Next it’s time to clean away the grime. Do this over a plastic tub using methylated spirits and an old toothbrush. Scrub until every last bit of grime has been removed.

Step 3.

Before we return the gears to the window, we need to ensure that they’re lubricated and protected from the elements. Apply your lubricant generously and use a soft cloth to distribute it across the entirety of the metal. Work it into the gears by moving them back and forth. When they move easily, you’re ready to reinstall.

Step 4.

Some casement windows are attached to an arm which runs along a track at the bottom of the window. These should be cleaned using a harsh, wire brush and solvents applied to a cloth (which should lift up all of those stray metal particulates).

Make sure you’ve gotten right into the track, and apply a layer of lubricant when you’re done, as just described. Again, you can work the lubricant in by moving the window back and forth.

Now, there are some instances where it’s impossible to repair the hinge, and you’ll need to look at replacing the hinge instead. Replacement hinges for casement windows are widely available and inexpensive.

How do you re-seal a casement window?

The seal around the edge of your window contributes enormously to its energy efficiency. If yours is damaged, then fixing it should be a priority. The stripping might have been pulled away from the corner of the frame, in which case you can address the problem by simply sticking it back into place with a dab of polyurethane sealant. On the other hand, repeated cycles of compression and expansion can, over the years, cause the stripping to lose its elasticity. When this happens, it’s time to replace it.

Step 1.

Pull the strip loose from the window. Do this slowly to minimise the risk of the wedge section of the strip remaining stuck in the grove. Should this happen, you’ll need to work it loose using a coat hanger or hobby knife.

Step 2.

Insert your new weather-stripping, starting from the corners. You won’t need to apply any adhesive, here; it should slide into the groove with a reassuring ‘click’.

How do you replace a handle on a casement window?

When your handle is spinning, but the window isn’t opening, a broken shaft is normally to blame. In most cases, this problem can be fixed with a replacement handle. You can buy replacement cranks which can be adjusted to fit different spindles, or you can contact the manufacturer and ask for a like-for-like replacement. If it’s the shaft itself that’s worn down, you can often correct the problem temporarily by filing the edge of the shaft so that the screw can lock properly. Don’t expect this fix to hold up for long if you’re opening and closing the window repeatedly, however.

Anything else?

Casement windows are incredibly robust and given the right care and attention, they’ll last for years. To stand the best possible chance of avoiding problems, we’d suggest taking a pro-active approach. Check your windows periodically for damage and if you notice a problem, don’t be tempted to delay in fixing it. The chances are that it’ll only get trickier (and more expensive) to solve!

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Victorian windows

A Guide to Victorian Windows

The Victorian era was one of enormous transformation for British industry and architecture. It was also during the Victorian era that window tax (a property tax based on the number of windows a house had) was abolished.

This result was homes being built with more windows. The industrial revolution also brought plate-glass manufacturing techniques which made large, heavy windows more affordable. Victorian windows were predominantly of the ‘sash’ variety. Victorian sash windows did not open out on hinges in the same way as casement windows, but instead incorporated two or more panels which moved behind one another on tracks.

If you’re the owner of a Victorian property, you’ll probably want windows that match the exterior of the building.

How Do You Clean Victorian Windows?

Ideally, windows should be cleaned twice a year – once in autumn, and once as part of your spring clean. Try to clean your windows when it’s cloudy, so the soapy water won’t dry out quickly and leave unsightly streaks on the glass.

What cleaner should I use?

Vinegar will leave your windows super shiny – and it’s safe and natural, too.  It’ll break down any caked-on grime in seconds, leaving a gleaming surface that’ll give the window a new lease of life.

That said, vinegar isn’t all that effective at killing germs, so we’d recommend at least occasionally using a specially-formulated window-cleaner, or old-fashioned soap and water. Scrunched-up newspaper or microfibre cloth should be used to work the cleaner into the glass.

Repairing Scratches on Victorian Windows

If you’ve been unlucky, some of the glass panels that make up your window might have received knocks and scrapes over the years. These can usually be addressed with a little cerium oxide (or jeweller’s rogue, as it’s better known). You’ll need to do a lot of rubbing to get this to work – either by hand, or with the help of a polishing pad attached to your household drill. You can also get special scratch-repair kits. They’re designed for car windows, but will work just as well on Victorian sash windows.

How Do You Insulate Victorian Windows?

Most homeowners choose double-glazing to increase the energy efficiency of their windows. By trapping a layer of inert gas between two glass panels, the transmission of heat from one side of the window to the other is greatly minimised.

Unfortunately, the difference in pressure between the interior and the exterior of a double-glazed window can produce a pronounced ‘bowing’ effect, which somewhat undermines the authenticity of a Victorian-era property. As such, it’s often frowned upon by conservation officers.

So what alternatives are available to owners of Victorian homes looking to reduce their energy expenditure?

Secondary glazing

Secondary glazing works in much the same way as double glazing, except that rather than having everything contained in a single pressurised unit, another window is placed behind the first one.

This will improve heat retention without compromising its appearance from the exterior of the home.

Unfortunately secondary glazing is vulnerable to sagging over time. An alternative is a sheet of plastic which can be unrolled and attached to the sides of the window in winter, when heat-preservation is more of a concern.


Victorian sash windows aren’t generally as effective at keeping draughts at bay as casement windows.

There are various ways to reduce draughts in Victorian-era windows, ranging from quick masking-tape solutions to major overhauls which require disassembling the entire window. Replacing old and worn brushes with new ones can have a considerable effect on the window’s heat-retention. This is worth considering if your windows are particularly old.

We should also remember that Victorian properties were built to ventilate, and that blocking draughts can cause moisture to build up inside the property, which can in turn, cause damp and mould.

How to Dress Victorian Windows

If you’re fortunate enough to live in a well-preserved Victorian property, then it’s important to keep all of your décor consistent – and this extends right up to the window dressing. In the Victorian era, most windows were equipped with wooden blinds and shutters, which provided protection against sunlight on warm days, and security when the homeowner was away.

bay window

Many Victorian homes also have high ceilings, which will allow you to stack roman blinds over the top of your window, and operate them with a cord.

Finally, you might want to hang heavy curtains in front of your windows. This will prevent the cold air near to the glass from mingling with the warm air in the room. If you’re going down this route, then you might want to install two sets of curtains: a lightweight ‘voile’ set that’ll ensure privacy while permitting sunlight, and a heavier blackout set of curtains to go over the top.

If you’re going to achieve a consistent and authentic look for your Victorian-era home, then taking your windows seriously is a must – but that needn’t mean compromising too much on modern conveniences like energy efficiency. Through regular maintenance, cleaning, and the right dressing, you can ensure that your Victorian-style sash windows last the distance – and that they look fantastic, too.

Need new windows? Browse our sliding sash or casement windows or find out about our handmade bespoke windows.

Wintery street

How to Winter-Proof Your Windows

If, like most of us, you want to reduce your heating bills, you’ll need to pay close attention to your windows – largely because they lose heat much faster than the surrounding walls. This, as you might imagine, is especially important when temperatures drop, so it’s worth thinking about before winter arrives.

What are the Most Winter-Proof Window Designs?

Let’s look at a few popular varieties of window, and how effective they are at retaining heat.

Casement Windows

A casement window operates via a hinge, and usually opens outwards. This makes it compatible with draught-reducing silicon seals, which run around the edges of the window and are compressed when the window is closed. These seals will degrade over time, gradually losing their elasticity, and so must be replaced every so often.

Sash Windows

By contrast, a sash window moves up and down (or from side to side) within the frame. In place of soft seals (which would create friction and prevent the window from moving), sash windows feature draught-excluding brushes.

Like the seals in casement windows, these brushes will wear away over time, and so should ideally be replaced every few years.

Older Windows

If you’re the owner of an older property in a conservation area, the changes you can make to your home will be limited. This is because your planning officer will want any replacement windows to conform with your existing windows.

houses in a UK village

In fact, it can sometimes be tricky to get double-glazing installed in older properties. Firstly, the difference in pressure between the interior and exterior of a double-glazed window can produce a noticeable bowing effect on the glass. Then there’s the fact that double-glazing for period properties tends to cost considerably more than typical double-glazed windows.

That’s not to say that owners of older properties are out of luck – there are plenty of new windows which work well in older properties.

Bay Windows

Bay windows, technically speaking, aren’t windows.

They’re groups of several windows, arranged together. As such, bay windows can either be casement or sash. Given that bay window protrude slightly from the building, they’re a little more vulnerable to cold spells than most other types of window.

This means you’ll want to dress the windows properly and ensure they’re thoroughly maintained.

Arched Head Windows

Arched head windows feature an arch at the top for added visual interest. The top of the arch is usually sealed into place, with the bottom of the window functioning like a traditional sash window.

What is Best for Winter: Double or Triple Glazing?

Argon-filled double glazing is the gold standard for modern windows, but there are ways to make the technology even more efficient. You could choose windows with a denser gas, like krypton or xenon – but that’s often overkill, especially since they cost considerably more than argon-filled windows.

Another option is to increase the depth of the cavity, but this would result in an incredibly thick window, and exacerbate the bowing effect we’ve already discussed. What’s more, a cavity that’s too thick can create convection currents, via which heat can be transmitted from one panel to the other.

In Scandinavia and other particularly-cold parts of the world, a popular solution is triple-glazing. Triple-glazing is formed of, as you might have guessed, three panels of glass rather than two.

houses in Svalbard

Triple-glazed windows are trickier to manufacture than double-glazed windows, so they understandably cost more. They also reduce the amount of light entering the property’s interior, and how much heat is gained through sunlight exposure. As such, if your window is south-facing, you might end up reducing the energy efficiency of your property by installing triple-glazing.

We should bear in mind that winter is relatively short in the UK, so the added expense incurred by triple-glazing should be offset against the light-reducing effect it has for the rest of the year. For most of us, there are many energy-saving measures worth considering before triple-glazing is worth the expense.

Window Ratings Explained

If you’re comparing different windows, you’ll have probably encountered all sorts of arcane terminology. To confuse matters further, British and American manufacturers use different rating systems.


The u-factor (or u-rating) measures the rate at which heat flows from one side of a window to the other. The lower the number, the more efficient the window.

U-rating is usually determined using the centre of the glass, which means the effect of the frame is discounted. You should expect a good double-glazed window to achieve a u-rating of around 0.3. U-factor is related to R-value, which is more commonly used to calculate the efficiency of solid brickwork.

Solar Heat Gains Coefficient (SHGC)

Whenever sunlight hits your window, some of it will pass through, leaving the remainder to bounce away. In doing so, this portion will help heat your property. The higher a window’s SHGC, the more heat it gains through solar energy. In winter, this extra heat will make a difference to both your comfort, and to your energy expenditure.

Visual Transmittance (VT)

This works just like the SHGC, except instead of measuring the proportion of heat energy entering the building, we’re measuring the amount of visible light. The two don’t always correlate, as manufacturers add special coatings that filter out certain wavelengths.

Air Leakage (AL)

Air leakage measures the volume of air that can circulate through a window in a given timeframe. The lower the AL rating, the draughtier the window. In many cases, a little circulation is required to allow the building to ‘breathe’ and thereby prevent damp.

British Fenestration Rating Council (BFRC)

The BFRC are the central body responsible for upholding window standards in the UK. They issue licences to approved manufacturers, and stipulate which retailers are authorised to sell approved windows. To make things a little less confusing for the customer, each window approved by the BFRC comes is rated between E and A++. This rating combines all the measurements we’ve described into a simple grade, so it’s easy to make rough comparisons between different windows.

How to Insulate Your Windows for the Winter

Whatever windows you’ve chosen, there are several steps you might take to increase their heat-retaining abilities for the season.

Heavy dressing

Heavy curtains can reduce heat lost through the windows by preventing the cold air around the glass from mixing with the warm air in the room. To get the best from this, you’ll need to actually draw your curtains at night-time.

Secondary Glazing

Secondary glazing works a little like double-glazing, except instead of two glass panels built into the same unit, a second panel is fitted to the inside of the existing window. Since there’s no pressure difference, there’s no bowing effect. What’s more, you can remove the secondary glazing when the weather gets warmer.

You can also get flexible and rigid plastic secondary glazing, called winter window clings, which can be fitted to the window frame for winter.


As windows age, the seals which run around the edges wear out – i.e. the stuff that runs around the edge of the frame, and the brushes and rubber strips that sit on the frame’s inside. Make a habit of inspecting these every year, and replace them when necessary.

Draught Excluders

These are long, tubular cushions, often crammed underneath leaky doors. If your windows are draughty, they can serve the same purpose.

Low-e glass

Low-emissivity glass is glazing that’s coated with a very thin layer of reflective metal, that helps prevent heat escaping. Most modern windows are low-emissivity.

Need new windows? Browse our sliding sash or casement windows or find out about our handmade bespoke windows.

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leaking window

How to Find, Fix and Prevent Window Water Leaks

A leaking window can spell big trouble – from damp in the home to structural problems.

However, by identifying and fixing leaks at the earliest opportunity, you can limit the damage they cause.

How to Find Window Leaks

You might assume that spotting a leaking window would be easy. If it rains and there’s water on the inside of the window, then you’ve got a leak – what could be simpler?

However, leaking windows aren’t always that obvious, and by being a little proactive, you can stop a small problem from becoming a very big problem – after all, most of us aren’t going to notice a few droplets of water unless we go looking for them.

That’s why it’s worth checking for leaks from time-to-time, particularly during winter.

One of the easiest ways to do this is with a special heat-measuring device that emits a beep when it’s pointed at a leak.

You might find that a leak of just a few droplets is worse than it at first appears. Where leaks occur inside a wall, the moisture will be quickly absorbed, so you won’t notice there’s a problem until unsightly splotches begin to appear.

The most vulnerable area of the window is the space where it meets the wall. This should be sealed to keep out moisture, but this seal can degrade over time, and must be periodically refreshed. The same applies to the rubber which holds the glazing in the frame, and the paint which seals a timber window in position.

What Causes Window Leaks?

The location of your leak will give you a fair indication of what’s caused it. A leak in the top of the window indicates a leak in the wall overhead – not the window.

A leak beneath the window, on the other hand, will probably indicate a problem with the window itself.

A lack of sealant around the edge of the window isn’t the only factor at work here. The problem can often be exacerbated by the building. If there isn’t enough overhang on the roof, then water will drip back onto the wall, gradually eroding the sealant every time it rains. If the fascia board (the bit that sits just beneath the edge of the roof) is angled toward the house rather than away from it, you’ll get the same problem.

Other issues relate to poor installation methods and materials. Windows should be sealed using window flashing rather than typical building paper. This will create a water-resistant seal that’ll protect the window. By the same token, if your windows have been poorly installed, gaps can quickly begin to appear between the frame and surrounding wall.

How Do I Fix Window Leaks?

Fixing a leaky window frame is often a simple matter of resealing the window. This means stripping away the existing sealant and applying a new layer. Sealant guns are inexpensive, and make the job as easy as pointing the nozzle into the gap and squeezing the trigger. Before the sealant has a chance to dry, spread it using a knife so that it covers the entire gap. You’ll want to check that the window is entirely sealed before you call the job done.

Occasionally however, the problem might be so severe that the window needs replacing – generally when the seal around the glazing itself has failed.

While it’s possible to reseal windows damaged in this way, it’s impossible to put the argon gas back into a double-glazed window once it’s escaped. As such, it’s worth replacing your window ASAP.

Another sure sign your windows need replacing is when the leaking has spread beyond the window, and the surrounding structure of the building has been compromised.

How Can I Prevent My Windows Leaking?

No window lasts forever, so you can be fairly certain that your window will fail at some point. It’s therefore worth inspecting every window in your home once a month or so. Check that the exterior sill is angled away from the window so that water can freely drain away, rather than collecting in a puddle.

Timber windows will need more frequent attention than uPVC windows, as uPVC is resistant to water by nature. You’ll want to periodically refinish your windows to help keep out moisture. The same goes for the drainage channel on hung windows – these can become blocked by fallen leaves and other debris, which will prevent water from draining away from the window.

You can often prevent window leaks by paying attention to the roof overhead – especially if it’s flat. As water pools on certain sorts of plastic roof, it can cause the surface to deform until the water cannot escape. The weight of the pooling water will then create enough pressure to cause a leak.

Saying that, sloped, tiled roofs aren’t immune, either; inspect them for gaps and damaged tiles, and re-seal vulnerable areas.

When leaks do occur, it’s worth bringing in a professional to identify the exact nature of the problem. This will save you considerable time and stress in the long-term.

Is your leak so severe you need new windows? Start shopping for our casement or sliding sash windows or talk to us about our bespoke window range.

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Condensation on window

What Causes Foggy Windows and How to Prevent It

Do your windows have a foggy appearance? Fortunately, as unsightly as it may be, window-fogging is a common phenomenon, and there are several ways of counteracting it, if not avoiding it altogether.

Why are My Windows Fogging Up?

In order to prevent windows from fogging up, you need to figure out what’s causing them to fog up in the first place.

Windows fog for several different reasons. All of them, however, can be reduced by the same phenomenon: airborne water vapour settling on a cold surface and condensing into tiny droplets.

These droplets diffuse light that passes through them, and thereby produce the ‘fogged’ effect.

Since glass is invariably among the coldest surfaces in the home, it’s here where you’ll first notice this fogging effect.

Windows fogging on the inside

Condensation on the inside of a window is caused by excessive humidity inside the home. You’ll notice this most often in winter, when the difference in temperature between the exterior and interior of the property is most pronounced. If you’re releasing a lot of moisture into the air by cooking or showering, then the problem is going to be even more apparent – which is why kitchens and bathrooms tend to be more affected than other rooms.

Windows fogging between panes

Double-glazed windows are formed of two glass panels, between which is sandwiched a layer of inert gas, typically argon. This gas is kept in place by air-tight seals running around the edges of the window. Should this seal start a leak, the gas will be able to escape.

This is usually noticeable when water-droplets appear the interior of the window, where they’ll condense. Manufacturers normally ship their double-glazed window with drying agents on the inside, which remove any moisture trapped during manufacture. If there’s a leak, however, these drying agents begin to lose their efficacy.

What Keeps Windows from Fogging Up?

There are two main ways in which you can prevent windows from fogging up.

  1. Raise the temperature of the glass so that water can’t settle.
  2. Reduce the amount of moisture in the air.

Since we want our windows to be as energy-efficient as possible, and there’s nothing we can do to alter the humidity outdoors, we should resign ourselves to the fact that fog on the outside of your window is a natural and largely unavoidable phenomenon. Fog on the inside of your windows, on the other hand, can often be corrected through proper ventilation.

A new window will be more efficient at keeping out drafts than an old one – and this can interfere with a building’s ability to properly ‘breathe’. This is why many new windows come with some form of ventilation built-in – most commonly, ‘trickle vents’, which constantly let in a steady stream of fresh air in the home (and let moist air out).

Other rooms may benefit from extractor fans – namely the kitchen and bathroom.

When you’re boiling pasta, crank the extractor to its maximum setting; it’ll suck up all the steam you’re creating. This will prevent water vapour from spreading throughout the room.

Similarly, an extractor fan near your shower will reduce moisture in your bathroom.

If your windows are fogging up even in environments where you aren’t creating moisture, you might consider investing in a dehumidifier.

Excessive airborne moisture doesn’t just cause your windows to fog up – it’ll also accelerate rot and other structural problems. This means you need to treat it seriously, even if you don’t need to see out of the window in your bathroom!

Do Foggy Windows Need Replacing?

If your windows are fogging up, then you might wonder whether your windows need replacing. If fog is forming between the panels of a double-glazed window, the answer is almost definitely yes. If this has happened, your window’s seal has been compromised and the unit will only continue to deteriorate over time.

You may be able to live with the problem initially, but eventually you’re going to need to get the windows replaced.

Boy cleaning window

How to Clean uPVC Window Frames

One of the major advantages of a uPVC window frame over timber is that it’s robust and long-lasting and requires minimal maintenance. While wood is naturally porous, uPVC is slippery at a molecular level. Consequently, it doesn’t require regular treatment with sandpaper and a pot of glossy finish. What uPVC windows do require, however, is occasional cleaning. Happily, this doesn’t take long, and will make a major difference to the way the windows ultimately look.

The Wrong Way to Clean uPVC Window Frames

uPVC is inherently vulnerable to certain sorts of mistreatment. It’s therefore worth pausing to think about what we shouldn’t be doing under any circumstances.

The surface of a plastic window frame is glossy and smooth, but scratch beneath the surface and the material is really dull. You can’t put uPVC back on once you’ve rubbed it off, and as such caustic cleaning agents and harsh scrubbing brushes are to be avoided. Even paper towels can be abrasive if used repeatedly.

Bleach should never be used on uPVC window frames, as it’ll discolour them. Unless you’d like your pristine white frames to turn an unsightly shade of brown, avoid it. Even small doses will cause a chemical reaction with the glossy surface of the plastic, creating a dull matt effect that can never be undone. Cellulose thinners are another item to avoid – they melt plastic, and will ruin your window almost instantly.

The Right Way to Clean uPVC Window Frames

The right approach is a gentler one. Ordinary soap and water, applied with a sponge or a soft cloth, will be enough to shift most stains. If you’re pressed for time, you might give the sill a once-over with a wet-wipe.

Alternatively, you can use a homemade solution, or a specialist chemical solution that has been formulated just to tackle uPVC.

Natural uPVC Cleaner

If you’d rather not spend your money on washing powder and wet-wipes, then why not consider a natural alternative? By mixing one-part vinegar with one-part hot water, you’ll create an acidic solution that can be applied easily using a spray bottle. You won’t need much to get the job done, and the acids won’t react with the uPVC in the same way that bleach will – just spray on a little bit and allow the solution to lift the stains away from the plastic. This will take around ten minutes.

After 10 minutes, wipe it clean – the dirt should lift off instantly. Don’t allow the moisture to sit there, or you’ll attract mildew. Once you’re done, you should be looking at a sparkling clean uPVC window frame.

Ready to replace your windows? Shop for sliding sashcasement, or made to measure windows.