Replacing your windows is sometimes the wisest choice you can make as a homeowner, especially if you’re in the middle of a single-room or whole-house renovation. New windows often represent a reliable investment, helping to make your home cosier, more beautiful and more energy efficient, or a combination of the above.

This guide aims to provide everything you need to know – including essential considerations and pointers – whether you’re thinking about window replacement in the long term or just moments away from making the commitment.

When to replace your windows

Breakage, damage, rotting or warping

If your window frame or sash is showing marks of significant wear and tear, from warping out of shape to clear signs of breakage, then a full replacement is almost always preferable to a repair job. Quick fixes, such as applying weather strips, may make the windows operable – but only in the short term. Whenever your windows start acting up – getting draughty, fogging up, refusing to close or open — avoid future hassle by calling in a specialist to appraise the situation and what’s needed.

Makeover time

The character of your home is heavily influenced by your chosen style of window as well as the condition they’re in. Worn windows make for a worn-looking house. It can’t be denied that warped or faded frames with old features gone out of fashion can have a significant effect on a home’s visual appeal. When you’re looking to revolutionise your look, window replacement is one of the first and most effective routes to consider.

Energy efficiency

In older homes, energy efficiency can be massively hindered by windows which are long overdue for an update. Upgrading to double-glazed units and specially-treated contemporary products, particularly in homes still using single pane glazing, can provide energy bill savings up to 15-20%.

Increasing comfort

With old-fashioned, out-of-date and ailing window frames you usually pay the price in comfort as much as with lost cash. The purchase of new energy efficient glazing systems with reflective properties should help to eliminate cold draughts in winter and prevent overheating through the summer.

Reducing noise

Single-paned glazing can present a lot of issues with noise. Whether you’re trying to work at home or catch a full night’s sleep while located in a busy area, silence is golden. Modern day glazing products typically come designed with noise reduction in mind, as well as a range of accessories and treatments to enhance their noise-cancelling properties. Double or triple-glazed and laminated frames can be extremely effective sound dampeners, in addition to features such as argon or krypton gas fillings, Low E coatings and basic weather stripping.

Long-term durability

Knowing that your old windows are on their way out, it’s important to make sure you’re investing in a long term improvement. Fortunately, newer high quality windows can be expected to perform for many years, with low maintenance requirements and notable associated savings – in both energy and money. Buying the right product with the right warranty can further extend the lifespan of your house renovation.

What replacing windows means for your home

There are three common methods for replacing windows, each with a different process implying different consequences for your home life.

Sash replacement

A sash is the part of the window which moves up and down. With sash replacement, old sashes and jamb liners (the tracks the sashes use to travel) are removed, with new versions re-inserted back into the original frame.

Consider using this method when you’re limited by budget and you can’t afford the disruption to your routine that is entailed by full frame replacements.  It is especially useful for slightly upgrading your windows’ beneficial properties while maintaining their existing aesthetics. However, the process is exclusively available for double-hung and picture windows, and is often reserved for wood and wood-clad windows only. Aluminium or vinyl products are not usually replaced this way.

Also worth noting is that the method relies on your window frames being relatively square and level. With square units, experienced fitters should find sash replacement to be a relatively easy procedure, causing very little disruption to the home as only composite parts of the window are replaced. Energy efficiency improvements can be significant in square units. However, many potential efficiency benefits are lost in less regular, non-square units, and they can be time-consuming to fix. For the most effective installation, applying weather stripping after installation is typically required.

Insert replacement / pocket fit

Insert replacement (or pocket fit windows) also involves the removal of existing sashes and jamb liners. A new window with its own frame is then placed within the existing unit’s frame.

This is the method of choice for those who want as much energy efficiency from their windows as possible while requiring the minimal possible disruption and cost. That’s because only parts and pieces are moved in the replacement process – just like with sash replacement. Furthermore, the process can be performed entirely from the exterior without removing any interior window stops. Most experienced mechanics will find this to be the easiest installation route, eliminating any potential complications from a lack of square structure as seen in sash replacement.

It is suitable for double-hung, casement, picture and awning windows and represents the most common method for vinyl window installation. With the replacement unit holding its own new sashes and frames, energy efficiency gains can be significant, although there is a chance of air leakage occurring around the original frame if you aren’t careful.

Although generally moderately priced, installation costs can increase depending on the custom requirements of your replacement window.

Full frame replacement

There is no compromise with full frame replacement. The interior and exterior trims are removed, the entire window and frame replaced within the wall’s cavity, and new insulation is fitted as well.

This method should be used by those who desire maximum efficiency from their windows in addition to a revamped aesthetic. Because the process replaces the entire existing window, it is easily the most disruptive to home life – potentially involving wall repairs and re-painting – as well as being the most difficult and time-consuming for installers. The silver lining of full frame replacement often comes in the form of an enormous potential boost to energy efficiency.

Although full frame replacement can be complex and is often a highly-priced service (due to labour and material costs) it is absolutely necessary in cases where frames are rotting and near collapse. Fortunately, the method is also applicable to all window materials available on the market.

Window replacement costs

There’s no getting away from the expense of window replacement. Prices will always vary depending on a number of factors – including material costs, locality, installer chosen and added or omitted features – but it’s safe to assume a whole-house window replacement will cost upwards of £4,500.

The window replacement process is not something you’ll want to repeat regularly. Although the result is a better looking, better feeling and more affordable household, there is plenty of work involved with sourcing multiple quotes and inviting installers to appraise and complete the job. Sourcing multiple quotes is essential to ensuring you get the best possible deal.

It’s also important to note that aluminium is one of the more expensive framing materials available, with four individual aluminium windows generally costing between £2,400 and £2,850.

Window replacement considerations

In order to maximise the performance of your new windows and minimise associated costs, there are a number of things homeowners should consider before beginning the replacement process.


The design or the specification of your replacement window is important as the choice of materials. The shape, orientation and placement of your windows can significantly affect the amount of solar heating, cooling and lighting in your home during different seasonal periods. Seek guidance to ensure you pick the design which will best enhance your home’s energy efficiency.


Replacement windows should help to maintain a house’s established character or enhance and improve its look. Choosing the wrong type of frame can detract from the house’s value, where well-selected frames can ensure a more positive return on investment when it’s time to sell up. Make sure to match the style of your new frames to the original or intended style of the house.

Adding value

As explained, renovating your windows isn’t just about maintaining appearances, it’s also about increasing the value of your home. It’s important, therefore, not to overspend on additional features and options which won’t affect visible or vital functionality. Low E coatings which improve efficiency, for example, are probably a more worthy investment than expensive triple glazing which is better reserved for extreme climates.

Professional installation

For best results, always hire an expert in the field. Attempts to save money through self-installation can ultimately lead to mistakes being made and costly fixes needing to be made in the future. Windows have to be air sealed and practically without fault in order to do their job properly – leave the task to home improvement professionals who possess the tools, skills and experience required.

High-quality glazing

If you’re committed to window replacement, there’s no point compromising on the quality of glazing. Up to 40% of a house’s energy is lost through windows, in both hot and cold environments. Opt for high-quality double glazing wherever possible to ensure lower energy costs and enhanced safety as well as a quieter, more protected interior to your home.


Aluminium window frames and sashes tend to possess poor insulation capability due to their metallic properties. It’s important, therefore, to compensate where necessary. Investing in double glazing, low-emissivity coatings and/or gas fillings can help ensure the greatest level of insulation possible.

Numbers and energy efficiency

When trying to ensure your choice of windows will perform to expectations, there are a few ratings schemes to look for, usually under an Energy Star or National Fenestration Rating Council label.

‘U-factor’ or ‘U-value’ is one such rating, ranging from 0.20 to 1.20, with the lower numbers representing the better heat retention performance. ‘Solar heat gain coefficient’ ratings go from 0 to 1, with the lower figure products being better at blocking unwanted heat – the warmer your local climate, the lower you want the number to be, and vice versa. There is also ‘visible transmittance’, indicating how much light a window lets in on a scale from 0 to 1: as the number increases, so does the amount of visible light transmitted.

Thanks for reading

We hope you find this article useful when considering the pros and cons of window replacement. If there’s something about the subject we’ve missed, don’t hesitate to contact us and let us know – we’ll add it to this guide as soon as we can.

In the meantime, feel free to seek some renovation inspiration and browse our range of premium aluminium window and door systems, all of which utilise high-quality double glazing and approved energy efficient materials.


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