Can I Reseal Double Glazed Windows?

Double Glazing is one of the most common window upgrades, enhancing both the comfort and the energy efficiency of your home. The two panes of glass with air or argon gas between them, slows the heat transfer from the inside to the outside by a large amount, meaning your home stays consistently warm for much less cost.

But what happens when the seal is damaged? Well, it’s no longer as effective and you lose much of the energy efficiency you were gaining with the double glazing. This is quite a common occurrence, especially as your windows age, so this raises the question — can you reseal your double-glazed windows?

Read on to find out more, as well as signs your window may need resealing, the process involved, and tips on how to better maintain your windows.

Can double-glazed windows be resealed?

Yes, provided your double-glazed windows actually have faulty seals as opposed to some other issue. Double-glazed windows typically have their seals fail through wear and tear, or sometimes through poor installation. Before we go into how to reseal the windows, let’s take a look at ways to identify when a double-glazed window may need resealing.

How do you tell if a Double-Glazed window needs resealing?

The following are how a double-glazed window may need resealing: 

  • Visual – The sealants exist around the window edges and can be identified visually. Look for any signs of cracks, peels or gaps within the sealant. Typically, sealants are to be uniform in appearance the whole way around. 
  • Condensation – If condensation is appearing on the inside of the window pains, then something has gone wrong. Double glazed are supposed to insulate and reduce condensation, so if it appears inside the windows, the seals are compromised. Note that some condensation doesn’t necessarily mean the seal is broken, as double-glazed usually reduces this by up to 80%. 
  • Distorted reflection in the glass – Double glazing is made up of two panes that are perfectly parallel to one another. This parallel nature allows both panes of glass to cast reflections as if there were a single pane. When this is not the case, and reflections come back looking warped and irregular, this is a clear sign that the gas/air between the two windows has leaked, resulting in lessened support for the parallel design. 
  • Drafts – Drafts are indicative of a gap somewhere in the window, although it’s likely you’ll only notice if you manually check. One good way to tell is to check the temperature of the window. 
  • Noise penetration – Double-glazed windows are not only good for blocking heat or cold but also sound. This is in large part due to the layer of gas between the panes. When it leaks through seal breakage, you’ll naturally begin to hear more of the outside. This is less noticeable for those in lower-population areas. 
  • Change in indoor temperature – The main reason that you want double-glazing is to keep the heat in your home consistent and pay less on bills. So, if the heat has returned near enough to the level it was pre-installation, then you’ve likely got broken seals.

How do I DIY reseal my double-glazed windows?

DIY resealing is harder the more extensive the damage is. The following is a DIY breakdown of how one would reseal their windows by themselves.

Gather Tools and Materials

The following are the tools and materials necessary for resealing a window by yourself: 

  • Utility Knife – Use this to cut away the old sealant. 
  • Putty Knife – Uproot stubborn sealant residue and clean the area. 
  • Caulking Gun – Use this to apply the new sealant efficiently. Get a silicone, high-quality caulking gun if you need to seal the outside. 
  • Rag – Cleaning the window frame and smoothing out sealant. 
  • Safety Equipment – Gloves will protect your hands, likely necessary when using sharp objects and the caulk gun. 
  • Cleaning Solution for Windows (optional) – To clean the window after removing the old sealant. 
  • Solvent for Windows – This will allow you to get rid of any particularly strong sealant residue. 

Remove Old Sealant

To remove the old sealant, you must carefully use the utility knife to slice through the old areas. You don’t need to dig it up using the utility knife, but simply slice away the large masses of it. 

When that’s done, you have to gently remove the parts of the sealant that remain firm on the surface of the window. For this, use the putty knife, and take your time, otherwise you may end up damaging one of the panes. 

As you’re removing the sealant, ensure that you periodically clean away the loosened material, dabbing at the area until it’s clear. This will allow you a good perspective on how far along the job you are, as well as make the next section easier. 

Once the sealant has been removed, you will have perhaps the best opportunity to check for any further damage that might’ve occurred to your window where the sealant used to be. If there is, it must be addressed before continuing to seal the window. 

Clean the Window

Now that all of the sealant is off the windows, it first needs to be fully cleaned away, which you should’ve made good progress towards during the last section. Once the sealant is mostly gone, use a wet rag to wipe down the entire area to get rid of dust and small particles. For a more thorough cleaning, consider using a cleaning solution.

Stubborn residue may require a solvent that’s safe to use with windows to properly clean away. Either way, when your windows are clean, ensure that you dry them.

Apply New Sealant

This is the critical step in resealing double-glazed windows. 

  • Preparation – First, you have to prepare the caulking gun. The tip of the caulk gun will have dried sealant at the tip. Cut it away, and then ensure that you’re using the gun at a 45-degree angle. 
  • Loading the Caulk – Press the release trigger then pull back the plunger. Put the silicone caulk tube into the caulk gun. Then push the plunger forward until it’s snug against the tube, and your caulk gun is ready to fire. 
  • Application – Position the caulk gun at the area where the window and its frame meet. Gently squeeze the trigger to begin the application. Move along the seams slowly, in a smooth and steady motion. The goal is an even bead of caulk along the entire length. 
  • Ensuring Even Coverage – Consistent pressure on the trigger ensures the caulk comes out evenly. The perfect amount to apply is a bead that doesn’t overflow. 
  • Avoiding Gaps and Air Bubbles – Having gaps and air bubbles in the caulk lines will reduce the efficiency of your windows, so ensure you correct it before the caulk sets. 
  • Smoothing the Caulk – Smooth the caulk using either your wet finger, or some other tool. 
  • Allow for Drying – Self-explanatory. Ensure nobody comes near the sealant for it to remain intact. 

Final Touches

When the sealant has finished applying, check them again to ensure it has applied properly. Anywhere where you can see thinner sealant is a place that should be touched up through reapplication. Otherwise, monitor the window over time, check for drafts etc.

Reseal a Double Glazed Windows – FAQs

Is it better to reseal or replace double-glazed windows?

It entirely depends on the condition of your windows.

Resealing double glazing has the following benefits and drawbacks: 

  • Cost-Effective – Resealing is much cheaper than replacing double-glazed windows. It’s mostly viable for those without the budget to replace windows. 
  • Environmental Impact – Resealing extends the lifespan of your window, preventing it from potentially causing harm when disposed of. 
  • Temporary Solution – Resealing is a shorter term fix for a window with broken seals. It won’t be as long-lasting as an entirely new, professional window. 
  • Possible waste of time – Defects in the window may be hard to detect. So, when you reseal your windows, it could be that some other issue is actually responsible.

Replacing double-glazing has the following benefits and drawbacks. 

  • Longevity – New windows are professionally installed, and protected with warranty and robust life expectancy. As such, your investment is protected through contract. 
  • Higher Costs – A new double-glazed window is going to be expensive. 
  • Upgraded Tech/Rating – Your old double-glazed window may have lower energy efficiency based purely on the fact that it’s an older rendition of double glazing. 
  • Disruption – New windows will equal higher installation times. This means you will have installers in your home likely making more noise for longer than resealing your windows yourself. 
  • Aesthetics and Value – Your new windows could have a better aesthetic, and that could, in turn, result in your home having higher value.

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