Repair Or Replacement Sash Windows?

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Welcome to Sash Window Refurbish

Experts in Sash Windows Repair & Restoration, Timber Windows & Timber Doors in east midlands

Why Trust Sash Window Refurbish?

Sash Windows Refurbish specializes in providing repair and restoration services for wooden windows and doors in the UK, as well as various types of carpentry. During the process of fulfilling orders, we utilize a range of tools and paints, including saws, sprays, primers, resins, and adhesives. With more than 20 years of experience in carpentry, we have tested and used various brands and types of work tools, making us well-equipped to offer helpful advice on selecting the right tools and paints for your needs. Read more ...

More and more homeowners are opting to restore their sash windows as opposed to replacing them altogether because they are cheaper and deliver almost the same results. If you are thinking of restoring your traditional timber sash window and wondering if you are making the right decision, then this article is for you.

We will tell you the benefits of restoring your sash window, available restoration options on the market as well as the cost and benefits of each option. Now, without further ado, let’s get started.

Sash Window Replacement or Restoration, Which is the Best Option?

Most homeowners with traditional wooden sash windows are torn between replacing the windows completely or restoring them. When it comes to replacement, you have two options.

They include full box replacement and sash-only replacement. If you choose this option, then we can give you professional advice by telling you what both options entail and the pros and cons of each to help you make an informed decision.

Sash Only Replacement

Sash-only replacement is a technique that involves retaining the current box frame and installing new glazed sashes on the existing box.

This is achieved by first removing the staff bead around the box edges as well as the parting bead that sits between the upper and lower sash. This move will enable you to remove old sashes with ease.

Once we are done with that process, the next step involves restoring, refurbishing, and redecorating the current box to bring it back to its former glory.

This is done using two topcoat layers of Teknos microporous plant and two primer layers. We have several RAL colour options at our shop. Just talk to us and we will give you the exact colour that you are looking for.

The final step involves swapping the sash cords and pulley system with brand-new ones that can take the weight of your new double glazing. The process is completed by inserting the new double-glazed sash in the box which is as good as new. That’s it.

Full Box Replacement

Full box replacement involves removing the architrave from the wall. This move will allow our technician to remove the entire box and install brand-new sash windows. This process will leave a hole in your brickwork.

The next step involves inserting a new full box into that hole. The new architrave is installed around the box on the inner wall to help to hide the join. The box is then sealed by pouring concrete.

The final step involves fixing any damage to the area where the box was removed. Our technician will go a step further and apply a fresh coat of paint so that nobody ever notices that some work was done on the window except enjoying the view of a stunning new window.

The entire box is new, meaning that everything in the box, including the security hardware, pulleys, sash cord, and opening hardware are all brand new. As a result, your new sash window will open and close with ease just as you wanted.

However, it is important to note that new sash windows, especially those made of softwood timber, require regular maintenance to keep them in good shape, especially in the first 5 years.

But as sash window experts, we always have a solution to every problem. When you hire our services, our team will laminate both the sills and lower parts of the original window, a move that will protect them from rot for a minimum of 20 years.

Once we laminate your wooden windows, they will have potent weather-resistant properties like windows made of Accoya wood, only that this time you have used a fraction of the cost.

Our cutting-edge technology allows us to restore traditional timber sash windows that last for longer than a new softwood-made window.

Will the Energy Efficiency of the Glazing Be Affected?

Not at all, the energy efficiency of the glazing will not be affected, whether it is a wooden sash window or a casement window. Sash window double glazing retrofitting which is a direct competitor of secondary glazing has a slim profile double glazing development.

But its popularity on the market was short-lived because the unit had a gas-filled leakage. But the development of vacuum double glazing changed the game.

Vacuum slim profile double glazing like the FINEO glass allows slim profile double glazed units to last for an extended period of time. In fact, the lifespan of a vacuumed sealed glass is more than 25 years and comes with 15 years of manufacturer warranty. This means that if the insulation fails, then the manufacturer will give a replacement at no extra cost.

Pros and Cons of Restoration vs Replacement

Now that you know what restoration and replacement are, let’s now take a look at their benefits and drawbacks. As mentioned earlier, restoring your current sash windows is cheaper compared to replacing them. It also causes less inconvenience. When well-maintained, restored windows can serve you for many years to come.

Pros and Cons of restored sash windows

  • They are energy efficient just like the new triple-glazed windows

  • They are by far cheaper compared to a new window with the same specifications

  • They preserve the original sash window look

  • You don’t need permission from local authorities to restore sash windows in grade two listed properties.

  • Scaffolding is not needed

  • The new retrofit double-glazing helps to reduce outside noise

  • It removes tattling and draughts

  • It is eco-friendly because less timber is used

  • The installation process is a bit noisy. It may affect your life, especially if you work from home
  • You need to do more research in order to get what you are looking for

  • It is quite complex to restore sash windows that difficult to find a good specialist

Pros and Cons of sash window replacement

Replacing all your current sash windows is quite expensive. The replacement sash process is also very noisy and may take time before you get used to it.

  • They are easily available. you can easily find a company that sells new sash windows within your locality

  • They have much better thermal efficiency compared to single-glazed windows

  • The attractive look that can increase the resale value of your property

  • The fact that it is new means that it comes with a manufacturer guarantee and insurance

  • It comes standard with draught proofing

  • Installation is regulated by FENSA CERTASS bodies

  • Brand new sash windows made of high-quality material like hardwood or Accoya are very expensive
  • Permission from local authorities is required if you are planning to change windows of grade 2 listed properties
  • The brand-new windows may change the original look of the property

  • Scaffolding is needed during the installation process

Sash Window Renovation – Is It Really Worth It?

YES, it is definitely worth it. Our cutting-edge technology allows us to restore sash windows to have nearly the same thermal efficiency as triple glazing and a lifespan of a brand-new window.

The cost of restoring sash windows is about £700 per window while draught proofing and double-glazing retrofitting costs around £1700 per window. This means that if you choose to restore your sash windows, you will save at least £1000 and still get the same performance that a brand-new sash window delivers.

Does It Affect the Environment?

Most people think that replacing an old sash window with a brand new one that is more thermal-efficient is good for the environment. However, that is not always the case. Although a brand-new sash window is thermal-efficient, the products used to manufacture it consume a lot of energy which is bad for the environment.

For instance, the energy required to make one tonne of glass is about 5.6 million BTU. A typical double-glazed sash window is about one meter wide and 2 meters tall and has about 50 kg of glazing.

Now, let’s do some simple math: 50kg/1000kg X 5.6 million BTU = 280,000 BTU, which is about 82111 Watts.

I know you are surprised to know this. This is something that the double-glazed salesperson will not tell you. They will only tell you that it is thermal-efficient and thus good for the environment but will not tell you the amount of energy used to build the sash window.

And remember that the calculation that we have done is of glass alone. We have not taken into account other factors such as the manufacture of the window, transportation, production of double or triple-glazed units, and more. One thing that we can tell you for sure is that the manufacturing process is always harmful to the environment.

But if you choose to restore your old sash windows, then you will truly play a big part in reducing carbon emissions because the process is 100% green.

If you have been thinking of whether to restore or replace your current old sash windows, we hope that this article will help you make an informed decision. As discussed above, both options have their pros and cons. It is upon you to choose one that suits your unique needs and budget.

About the author

Glen Ramsey, who presently holds the positions of customer support and content manager, is a cherished member of the Sash Window Refurbish team. He is in a unique position to provide advice on all questions pertaining to the renovation of historic windows because he has a wealth of experience in all elements of window renovation, dealing with clients regularly and assisting them in choosing the best window-related course of action. He oversees the creation of information for all of our platforms in his capacity as content manager, including web content and other materials. Glen has witnessed the whole gamut of Sash Window Refurbish's window restoration activities, from our work on significant listed Georgian homes to a wide variety of smaller-scale private residential projects.


My technician Andrew replaced all my sash windows that had rotten sills. Accessing the rotten sills was not an easy task. He explained to me what needed to be done in order to fix the problem. He is a great person and I’m happy that he was the one who did the job. He is reliable, tidy, friendly and very professional. I highly recommend him.



I hired Andrew and Alex a while back to repair my damaged sash windows. They were was very considerate and very patient as he did his job. A few days ago, I had another problem with one of my sash lock keys and I called him again to come and fix the problem. I’m very impressed that Liam responded quickly and he not only fixed the problem but he also gave me a spare key. What a great after sales service!

Alan W.


I’m very impressed with the new windows that Andrew installed and also the reconditioning job that he did on other sash windows. The quality of his work is by far more superior than what we got when we hired another company a few years back. We will certainly hire him again if any window work arises

Kelly (Sleaford)


Our decorator referred us to Andrew because some of the work needed a window expert. Andrew together with our decorator did a fantastic job. The work was done efficiently and to the highest standards. Andrew is understanding, committed and very professional. I recommend him without any hesitation.

Steaven Reader


Alex did a great job in fixing windows in our terraced house. The windows were broken, frames damaged and the wood was also rotten. Alex's job was high quality and he did it pretty fast. I was also very impressed that he was considerate of my son’s asthma condition and maintained cleanliness. Top work.



Andrew just recently replaced three sash windows in my Edwardian house. He also repaired and replaced some sills and draught proofed three windows. In addition to that, he also did some carpentry work. What I like the most about Liam is that he did a clean job. He is very professional and always updated me about the timescales and costs. He also did his job with minimal disruptions. I highly recommend him.

Cris M.