Cost of Replacing a Sash Window

August 7, 2025
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Cost of Replacing a Sash Window
An old sash window being replaced.

Sash windows will never be out of style. Whether you own a period-style home or simply love the look, you’ve likely become fond of your sash windows. However, nothing lasts forever. Weather damage, rot, warping, cracking, or swelling may be among the reasons you’re eying your windows and wondering about sash window replacement costs. 

There is no simple answer because a lot of the factors affecting price depend on what you want from your windows. Nevertheless, we can look at some of the key considerations that will affect the cost of replacing sash windows and your ultimate satisfaction with the results. 

Why Replace Sash Windows?

Apart from the structural condition of your sash windows, there are other reasons why you might consider replacements. Energy efficiency and indoor comfort are among these. Old sash windows may still be single-glazed, and if your windows have aged, they can let in chilly draughts just when you most want to keep cosy. Replacing them means lower energy bills and a more comfortable home. 

Security is also an important consideration, especially nowadays. Old sash windows may have weak locks, and weakened frames mean that simply replacing window locks won’t improve your home’s security. If this is one of the reasons why you’re considering replacement sash windows and their cost, cheap options simply won’t do for you.

Finally, there’s the matter of looks and convenience. Modern sash windows can give your home a new look while maintaining a classical feel. They also feature a much simpler and smoother mechanism that allows them to open and close smoothly and easily. 

Restoring Or Replacing a Sash Window

If you’re interested in how your home looks (and who isn’t?), you will almost never restore or replace only one sash window. Bear in mind that whatever you commit to applies to all your windows. It’s a big decision to make, but we will try to make it easier. 

Restoring and repairing sash windows, particularly old ones, is going to be a massive task. To do a proper job, you will have to remove them, and the restoration itself isn’t going to be a hasty affair. Think about replacing damaged timbers, draught-proofing, and, in some instances, adapting the windows to accommodate double glazing. 

Sometimes, old sash windows are past praying for. They’re rotting from the inside, warped, and no repair job, even supposing repair is possible, is going to last long enough to make the exercise worthwhile. 

Now to weigh costs against benefits. It's faster and less disruptive to replace sash windows, and if the ones you choose are good quality, you shouldn’t have to spend time maintaining them in any hurry. On the other hand, restoring could (but won’t always) be a cheaper option.

What Determines the Cost of Replacement Sash Windows?

It’s time for the meaty part - looking at the reasons why we can’t simply say “replacing sash windows costs £X. Instead, we will examine what costs more, what costs less, what’s durable, and other factors that impact the total cost of replacement sash windows. 

1. Materials

There’s more to this choice than simply deciding between timber and super-cheap uPVC. There are also composites, engineered wood finishes, and more. On the whole, timber is a pricey choice, and not only in terms of its initial cost. Much as we love wood, it needs maintenance or it simply won’t last. 

uPVC is cheap and cheerful and can actually look quite good. It is less maintenance-intensive than wood and should last around 25 years. It can even be more secure than wood if you choose a high-quality option. That pushes up the price, but you trade that for a little more peace of mind. However, there’s an even better option. 

Composite sash windows consist of layers of different materials. Like uPVC, you get good composites, and rather less-good ones, and the better the composite, the higher the price. However, high-quality composite sash windows offer multiple advantages. 

For example, at Stronghold Security Doors, sash windows are reinforced with steel and finished with high-quality engineered wood that resembles the real thing but remains maintenance-free for longer. Best of all, although it isn’t the cheapest, it’s affordable enough to be on your radar. 

2. Size and Customisations

It stands to reason. Smaller windows are generally cheaper than big ones. Standard size windows? You might consider mass-produced sash windows. It will limit your choices - after all, the only option is what comes off the production line, but there is a cost advantage. 

However, you might have, or want to have, nonstandard-sized window openings. Or, you might just want to do a bit of designing on your own behalf and come up with some ideas that break free of the everyday mould. You may also have a preference for specific types of sash windows. Simply put, the size of the windows and the degree of control you want to have over their design will affect pricing. 

3. Glass Options

Sometimes, it’s the things you can’t tell at a glance that make all the difference, and glass options are among these. Of course, you will want to opt for double glazing, which is costlier than single-glazing, but there are multiple options to choose from. 

You could opt for laminated safety glass, triple glazing, acoustic glass, or P6B security glass, which can withstand hammer blows. You may even prefer bulletproof glass, especially if you’re a high-profile person. All in all, your choice of glazing should be based on your needs and preferences rather than cost. However, it’s safe to assume that better quality means higher cost. 

4. Bar Work, For Example, Astragal or Georgian Bars

If you’re looking for a classic appearance or want to add a custom configuration of your own, you will need to factor this in as an additional cost into your sash window replacement. By way of explanation, astragal bars are fitted onto the glass and are purely ornamental. Georgian bars divide the window into separate panes.

5. Colours and Finishes

Plain, white uPVC is definitely the cheapest option you can choose. However, you might have more creative ideas on your mind. No matter what type of replacement sash window you choose, custom colours and finishes will add to the overall cost, even if you paint your sash windows yourself. 

At Stronghold Security doors, we do not charge extra for your choice of colours. Instead, we allow our customers to choose between 150 shades and we custom-make their windows in the precise colour they prefer. 

6. Can I Replace Sash Windows Myself?

Installing sash windows is a precision job. Even if you’re determined to do everything correctly without shortcuts, there may be a learning curve - and it can prove costly. So, the answer is yes. You can replace sash windows yourself, but there is no guarantee of success. 

It makes better sense to protect your investment by choosing professional installation from people who are willing to guarantee their work. That way, supposing there are any hiccups (and there shouldn’t be), you aren’t left with the problem of correcting a botched installation. 

Finally, if you live in a conservation area, you may need planning permission for your new sash windows. A professional can help you navigate the approval process and will know how to meet all the requirements. 

So, How Much Does it Really Cost to Replace a Sash Window?

We suggest that you compile a list of ideas that describe a suitable replacement sash window. Then, shop around, compare prices, and consider the benefits and drawbacks of each option. Be sure to add Stronghold Security Doors’ security sash windows to your list. We are not the cheapest, but we offer a good price point for the superior quality we produce and the security features our windows offer. 

With us, replacing your sash windows need not be a major drama or inconvenience. We will begin by consulting your preferences, follow by producing exactly what you asked for, and finish the project with professional, hassle-free installation. Our work is guaranteed. Remember to browse our gallery to see some of our past projects. We take pride in our work! Need a price for replacement sash windows as beautiful as the ones you see on our website? We are a phone call away.