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How to seal external windows

How To Seal External Windows

Everything you need to know about how to seal external windows is on this page, from how to clean, apply and what mastic to use when sealing external windows.

Why Should I Seal External Windows?

When your external windows are fitted there will be a small gap around the perimeter of the frame, if this small gap is left unsealed heat can escape the house and water can seep inside the house.

 

Windows are the barrier that stop the elements from coming into your home. If water manages to seep through the small gap between the window frame and wall water can stay underneath the frame for a long period of time causing rotting, flooding and a build up of mould that can be costly and hazardous to health. Heat can also escape through these small gaps which will great quite a high energy bill just to warm the house. Sealing these gaps with an external silicone sealant can prevent all of the above.

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Another reason to seal/reseal your external windows is to make it stand out. Old sealant can start to lose its fresh look and can collect mould over time. You can remove old sealant and apply fresh high quality external sealant to spruce up your home and give your windows a brand new look.

What Do You Seal Windows With?

To seal external windows with external silicone sealant - you’ll need the following equipment:

  • Stanley knife

  • Caulking gun

  • High quality external silicone sealant 

  • Silicone smoother tool 

  • Frog tape 

  • Backing Rod

External Window Sealants 

Listed across is a range of the External window sealants you can use to seal your external windows, We offer these weatherproof external sealants in our store, they come in a variety of colours and sizes to meet your needs.

What Areas Of Windows Do You Seal?

When sealing external windows you want to make sure you seal all of the correct areas so there is no heat escaping and no water leakage. 

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Window Frame -  When sealing the external windows you want to seal the whole perimeter of the frame to the wall using external silicone sealant. This will stop water from leaking underneath the window frame and prevent any drafts. 

Hw to seal external windows step by step

How To Seal External Windows 

Step By Step

Once you’ve got your equipment and tools, it’s time to start sealing your external windows.

 

Preparing the Silicone

Firstly you are going to want to find the correct external sealant or from a shop. There are many good brands out there to choose from, Everbuild is a high quality brand you can use to find the correct mastic for your external windows. 

use your Stanley knife to cut the silicone sealant tube open. Before attaching the head or nozzle of the silicone, cut the tip as close to a 45-degree angle as possible, this will make applying it much easier and neater. Then place the silicone into the caulking gun and pull the trigger slowly until you feel a bit of resistant so that the tube is securely in the gun and will not fall out.

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Clean the surface

You need to make sure that before applying the silicone that the surface has no dust, residue, water or old silicone if reapplying. You can wipe the surface down where silicone will be applied but you need to make sure it is then dried afterwards because silicone will not bond to a wet surface.

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Apply the sealant

Firstly put the backing rod in the gap you are wanting to seal and tape the sides of the window frame and brick work to avoid the sealant to sticking to the brickwork or window frame. then get as close as possible to the edge of the area you want to seal, and then apply the silicone by pressing the caulking gun trigger. In a smooth movement, begin from one end and work you way to the other end. Do not touch the sealant once you have have applied until you have sealed the whole area. When finished Applying click the leaver on the back of the sealant gun to loosen the tube and stop sealant from oozing out the nozzle. Cover the end of the nozzle so no excess sealant spills on the floor.

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Smoothing the sealant

Now spray the sealant you have applied with water (Water helps remover the excess sealant and stops it from sticking), then grab your sealant tool. Start from one end and slowly smooth the sealant bead until it is neat and flat. Make sure you have the wonder wipes ready for when excess forms on your sealant tool, do this until the perimeter is sealed. Your windows should now be sealed properly. you may want to have a look over and run the tool over any bits and are a bit wider or need slight touching up. If there are gaps this is no problem you can re apply and start the process again in that small area. After you are happy with this peel off the tape.

Give the sealant 24 hours to cure do not run any water or disturb the sealant during this time. 

Removing Old Window Sealant 

To remove old sealant you will need a Stanley Knife a small scraping tool, sealant remover and some sort of cloth. 

Start by running the Stanley blade down the centre of the sealant, next scrape away as much sealant as you possibly can using the scraper (be carful not to damage the window frame or the brickwork whilst doing this). Apply the sealant remover to the left over bits of sealant and leave it for 15 minutes. 

Now you can rub over the sealant with a cloth and it should peel away quite easily. 

The sealant removing process is a lot more time consuming than applying sealant. Once you have finished removing all sealant you can now clean down the area and re apply.

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