If you’re considering installing aluminium window frames, most people assume they feel cold because aluminium is thermally conductive, so you might wonder how to insulate them at home.
The good news? We’ve got the answer to this question and all the information you need to make the best decisions about a new window with effective insulation.
So, prepare your toolboxes and get ready to learn about insulation and aluminium windows.
Are Aluminium Window Frames Good for Insulation?
On its own aluminium conducts heat, but modern aluminium frames have a polyamide thermal break separating the inner and outer sections, and with double or triple glazing they meet UK Building Regulations. Older frames without a thermal break feel cold and benefit most from extra insulation. Read more about window U-values.
Aluminium is a type of metal and is thermally conductive, so it’s not the first material we think about when talking about insulating heat in the home. However, aluminium allows you to use super sturdy double- and triple-glazed windows that are very effective when it comes to insulating your home.
Modern thermally broken aluminium windows are designed to comply with Part L of the Building Regulations, so a quality product should already be energy efficient.
Aluminium window frames are solid and durable, allowing them to take on a lot of wear and tear when compared with other materials.
So, while other materials like plastics and wood may be cheaper, they may need replacing more often or be easier to replace than aluminium.
Why Does Window Insulation Matter?
Windows are one of the biggest sources of heat loss in a home. Better-insulated windows keep rooms warmer, reduce draughts and condensation, lower energy bills and help you meet Building Regulations when replacing windows.
Insulation is an important consideration when buying and installing any fixtures and fittings around the home. UK homes fall under strict regulatory guidelines that dictate how energy-efficient it needs to be.
It is essential to follow these guidelines, because insulation helps prevent heat loss, keeps your home warmer, maintains a more stable indoor temperature, and ultimately saves you money on energy bills!
While this is vital, more importantly, having an energy-efficient home reduces your carbon footprint and reduces your impact on the planet.
We all need to do our part to combat global warming, and starting with proper insulation is a good first step.
What Are the Benefits of Aluminium Windows?
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Durability: Aluminium is extremely strong. It can withstand a lot of wear and tear and hold up a glass with energy-efficient glazing and lamination.
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Thermal efficiency: Aluminium is not thick by design; however, the many layers inside the window frame give it its sturdy nature. This prevents draughts leaking through, which can lower energy efficiency and cause heat loss, helping keep warm air inside during winter.
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Easy maintenance: One of the top advantages of choosing aluminium is that it is low maintenance and easy to maintain. You don’t need special tools and products; with a simple cloth and water, you’re good to go.
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Eco-friendly: Aluminium can be recycled after use, lowering the impact on the environment across the building. Additionally, the thermal efficiency also makes aluminium very eco-friendly.
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Design: Aluminium offers a sleek and modern finish that is the perfect addition to any home, whether old or new. It can take you from drab to fab with a few minor features. Aluminium comes in almost any RAL colour, so you can match new windows to aluminium bifold doors or single aluminium doors.
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Flexibility: Aluminium windows can be made in almost any size and configuration, including bi-fold windows, giving you control over how many panes there are and how large they are.
If you’re still wondering what are the benefits of aluminium windows, we have a whole article to break things down.
Which Glazing Is Best for Insulating Aluminium Windows?
Triple glazing gives the best insulation, followed by high-performance double glazing with low-E coatings and argon gas fill. Laminated glass adds security and noise reduction, while integral blinds help control heat gain and loss.
There are a few options to choose from when selecting glass for your aluminium windows:
Double glazing: An insulating layer is added between two pieces of glass to add a layer of security and sturdiness. Secondary glazing adds insulation while also protecting against UV.
Triple glazing: The same as above with an extra pane of glass, adding more insulating properties and protection.
Laminated glass: Two pieces of glass bonded together with a thin layer of plastic. If hit, the glass will crack but stay together.
Integral blinds: A new and popular system. Integral blinds look like traditional blind units, but rather than being on the outside are placed between two layers of glazed glass. You can manually or automatically open and close the blinds. This system helps prevent damage and keeps your windows protected for many years to come.
How Do You Insulate Aluminium Window Frames?
The most effective DIY methods are to seal gaps between the frame and the wall, fit rubber weather strips where the sashes close, apply insulating window film and hang thermal curtains. For a lasting improvement, add secondary glazing or replace old frames with thermally broken units.
Before getting into how you can insulate aluminium windows, it’s important to know that having a well-made product shouldn’t require you to DIY insulation.
Good-quality, thermally broken aluminium windows are very thermally efficient and draught-proof. The degree of this, however, will depend on the glass you choose to install.
If you’re in a bind and need to insulate the windows yourself, there are ways to do this without it being too much of a hassle or great expense. In some cases, DIY insulation is a temporary solution, and some methods can help without requiring permanent modifications.
Step 1: Seal Gaps Between the Frame and the Wall
Check around the outside and inside of the frame for cracked or missing sealant. Cut out failed sealant, clean the joint and run a fresh bead of low-modulus exterior silicone; larger internal gaps can be filled with low-expansion foam before sealing. Our guide on how to seal aluminium doors and windows covers this in detail.
Step 2: Fit Weather Strips Around the Opening Sashes
Weather strips are a good option if a noticeable draught comes through a part of your window frame, and they improve sealing around gaps in the frame.
The product blocks the draught once it’s been laid down around the frame. But it also adds an extra layer of protection from bad weather.
Rain, wind, and snow can cause dampness in the home, particularly if aluminium frames aren’t correctly made and lack weather-resistant materials and features.
Weather strips come in various materials, including foam, plastic, felt, vinyl, and metal. On aluminium windows, self-adhesive EPDM rubber or silicone strips usually work best, as they compress well and resist weathering.
How to: Once you have your product, measure the size of the aluminium frames, cut the strips, and attach them around the frames.
Step 3: Apply Insulating Window Film
Insulation window film is a type of plastic attached to double-sided adhesive tape around the aluminium frames, then stretched over the window.
It is a cheap option to get the job done quickly and without much hassle.
How to:
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Once you have your insulation film, cut the plastic to size, but leave about 5%-10% excess on the sides.
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Stick down the double-sided tapes around the aluminium frames. Generally, it’s best to stick the tape in the middle of the frame panel or window sill, as this helps create a still air space between the glass and film.
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Place the plastic onto the tape, making sure the film is attached firmly and smoothly.
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Use a hairdryer along the edges of the tape to seal the adhesive to the film. Start in one corner and work your way over the entire film over the window.
This is a practical option when you want extra insulation without permanent modifications on the other side of the frame.
While it’s not the most visually appealing, insulation film can help keep heat in the house, remove cold air draughts, and remove UV.
Step 4: Hang Insulated Curtains
If you’re renting and can’t use the above methods to insulate aluminium windows, insulated curtains can be a real lifesaver.
If there are curtain rails up, it’s a simple matter of buying the curtains and putting them up.
How do insulated curtains work?
Insulated curtains have multiple layers that act as a barrier to heat, UV, and sound.
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First layer: Contains a reflective film that redirects heat into the room.
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Second layer: A vapour barrier to keep moisture out (this is important during the rainy season. Materials with condensation or vapour contamination can mould).
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Third layer: Foam that blocks cold, maintains heat and reduces sound waves.
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Internal layer: Usually a decorative layer that doesn’t compromise aesthetics for function.
Insulated curtains are an excellent option for those that don’t want to compromise their window’s warranty.
Remember, modifying your frames within the warranty period may affect your warranty, so check the terms before doing any work yourself.
The only downside to insulated curtains is that they don’t fix the problem if you have cold air or draught coming in.
Step 5: Add Secondary Glazing
Secondary glazing adds a separate pane on the inside of the existing window, creating an insulating air gap that cuts heat loss, draughts and noise. It's reversible, so it's a good option for rented, listed or older homes. See whether you can retrofit double glazing into existing aluminium windows instead.
Should You Insulate or Replace Old Aluminium Windows?
If your aluminium windows have no thermal break, single glazing or failing seals, DIY insulation will only ever be a partial fix and replacement with modern thermally broken, double or triple glazed frames is usually the better long-term investment. If the frames are sound and simply draughty, sealing and weather strips are often enough. Compare costs in our aluminium window cost guide.
Aluminium Window Insulation FAQs
Are aluminium windows thermally efficient?
Yes, modern aluminium windows are thermally efficient because a polyamide thermal break separates the inner and outer sections of the frame, stopping heat escaping through the metal. The windows can withstand much heavier glass than wood, plastic and uPVC windows, so triple- or double-glazing is an option, no matter your window size.
How do I know if I need extra window insulation?
You will know if your windows are not appropriately insulated with a window seal by the heat loss in your home. Any room that doesn’t have insulated windows that properly fit will be much cooler. Also, if you can hear a draught or feel one around the edge of the frame.
Does the type of glass affect insulation?
Yes, you must carefully select the type of glass with insulation in mind. Triple and double glazing are popular. But other options exist, including lamination and integral blinds. Ask your installer for the whole-window U-value of each glazing option before you decide.
How do I stop cold coming through aluminium windows?
Start by sealing gaps around the frame and replacing worn gaskets or brush seals on the opening sashes, then adjust the hinges and keeps so the sashes close tightly. Thermal curtains and window film help further. If the frame itself feels icy, it probably has no thermal break.
Can you add a thermal break to existing aluminium windows?
Not practically. A thermal break is built into the aluminium profile during manufacture, so it can't be retrofitted to old frames. Frames without one need extra insulation measures or replacement with modern thermally broken windows.
Will insulating aluminium windows stop condensation?
It helps, because warmer frame and glass surfaces are less likely to reach dew point, but ventilation matters just as much. See how to prevent condensation on aluminium window frames.
