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How To Seal Windows Help and Advice

How To Seal Windows

Posted on 05 July, 2021

How To Seal Windows

Very similar to how to seal a bathroom, knowing how to seal a window is important to prevent unwanted draughts and water from getting into your property.

Why windows need to be sealed

Draughty windows majorly affect the warmth and comfort of your property, allowing in excess air from outside throughout the seasons. Being able to feel a constant draft is both irritating and frustrating, as well as the constant reminder that hard-earned cash spent on heating your property is being wasted.

Around 35% of the heat in your home can escape through the gaps in and around windows and doors*

As well as this, sealing draughty windows is important to prevent damp from penetrating internal walls and window frames, as well as disallowing water from getting inside your property.

How to check for draughts

Sometimes finding exactly where a draught is can be difficult. To overcome this, simply strike a lighter or light an incense stick. Hold near joints and connections of the window to check for leaks. If the flame/smoke flickers when near a certain area, you have a leak there. 

Make sure you check:

  • Where sections of the window meet
  • Where the window meets the frame
  • Where the window frame meets the wall

How to seal with sealant

When the connection between the window frame and the wall is broken, it’s likely that water will be able to enter your property through this crack. Any cracks between the window and wall, including between windowsills and walls, can be fixed by using a window frame sealant to seal all gaps. This method is ideal for sealing all types of uPVC windows and doors.

What you need:

  • Suitable sealant
  • Scraper/putty knife/screwdriver/special sealant remover

What to do:

  1. Clean down all areas that are about to be sealed with the sealant, making sure to get rid of any old sealant by carefully using a scraper/putty knife, screwdriver or special sealant remover
  2. Apply the sealant to all joints and connections that need securing
  3. Hold the sealant as close to 45 degrees as possible, as that’s best for getting deep into the crack/gap
  4. Make sure you are moving in one continuous direction
  5. Ensure the sealant sticks to both sides of the crack- both the window frame and wall
  6. Get rid of any excess and unnecessary sealant.

Alongside the option of window caulking, a strong waterproof grab adhesive would also do the trick to fill the unwanted gaps. You might choose to use a sealant/caulking gun to help with precision, but this isn’t necessary.

How to seal with expanding foam

You can carry out a more effective and permanent job of sealing window and door leaks if you’re willing to remove the exterior or interior window trim. Although using a sealant is typically easier to do, using expanding foam does a much better job of protecting your property from water and unwanted air.

What you need:

  • Crowbar/Pry bar
  • Hammer
  • Suitable expanding foam
  • Knife
  • Paint (not always necessary)

What to do:

  1. Using a crowbar and a hammer, remove either the inside our outside window trim. It’s important that you do not remove both
  2. Fill the gap/void with the expanding foam. Don’t worry about putting too much on, you can always scrape any excess off after. Make sure you don’t touch the foam while it’s still wet.
  3. After several hours, the foam will have dried. Cut off any excess foam with a knife if needed.
  4. Replace the trim in the reverse order in which you removed it and go over any spots with paint if necessary.

Sealing window frames and filling in cracks and gaps around windows and windowsills has never been easier with BC Profile’s professional range of materials. Browse BC Profiles today and discover a wide variety of sealantsgrab adhesives and expanding foam. For more professional advice on how to seal windows, get in touch for expert tips from our team. 


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