How to Seal Aluminium Windows

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So, winter’s arrived, and you’re noticing a leak in your aluminium window frame. Now what? 

Don’t panic! We have the solution for sealing up your aluminium window frame when you don’t have the time to get a professional in. 

Continue reading to find out how to insulate aluminium window frames and seal them so you have no future problems and can achieve a lower U-value for your window.

Knowing When to Seal Aluminium Window Frames

The two most significant ways to know if you need to seal your aluminium window frames are draught and condensation. 

A draught is noticeable when you hear the air coming through the frame or if the room is significantly colder than other rooms with aluminium windows. 

You can hold a lit candle while slowly circling the window frame edges to detect a draught. If there is a draught, the flame will move to signify approaching air.

Condensation is easier to notice from the puddle on the window sill or the streaks of water running down your windows.

You will also need to stop this water from leaking through the window if sealing is required on your window.

Sealing Aluminium Windows at Home

Here is a step by step to sealing your windows:

What you’ll need:

  • Silicone sealant (caulk)
  • Caulking gun
  • Masking tape
  • Release agent
  • Cleaning supplies

What to do:

  • Clean the entire window and frame of any dirt or dust. Remove soap residues with a damp cloth before you start sealing.
  • Look for gaps where the draught or condensation is coming in.
  • Apply a release agent (a silicone-free compound). To prevent the silicone sealant from clinging to the window’s attachment points to the frame.
  • Stick tape around the sealant edges of where you want the sealant to go to prevent any wonky lines. 
  • Apply sufficient sealant around the window and smooth carefully to get it as even as possible. Using a caulking gun can help you distribute the right amount of pressure and product. 

Note: you shouldn’t try applying silicone sealants to damp surfaces. If the window or frame is wet to the touch, the silicone will slide off. It needs to be as dry as possible.  

If the sealant appears wet, you’ll need to do it again.

You can follow our tips for in-depth insight into everything DIY with an aluminium frame.

Which Windows Are More Likely to Need Sealant?

Draughts are more common in older windows or windows that don’t have specific glazing. Thank goodness for triple and double glazing. 

Selecting triple and double glazing can make a massive difference for sealant issues.

We’ve got you covered if you decide to upgrade to double or triple glazing. We offer a variety of aluminium door frames and windows. They will give you the peace of mind that they seal so tightly that draughts or leaks won’t be an issue in the future.

Find the right aluminium windows and aluminium doors for you. There are draught-proof choices, such as roof lanterns for your ceiling, aluminium bifold doors, aluminium French doors, and aluminium patio doors.


How do I know if my aluminium window needs sealing? 

There are two ways to tell: draughts and leaking. If you notice any air passing through or condensation on the window frame, a seal is needed. 

What do I use to seal my aluminium windows? 

There are multiple products on the market, but a silicone caulk sealant is best for a window with a leak. Also, using a caulking gun helps keep things even.

Can I seal a leak in my aluminium window myself? 

Yes, you can. However, this is only if the leak or area that needs sealing is relatively small. Extensive open spaces around your aluminium window won’t close with at-home silicone caulk. It’s always best to call your aluminium window installer to find the best way forward.

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