How to Reseal Windows: 2024 Step-by-Step Guide for Beginners

Table Of Contents

The first thought that might come to your mind whenever you notice drafts seeping through your office windows is to tape them over. However, taping over the problem isn’t ideal — it’s time to reseal those panes properly.

Windows seals have an average lifespan of 10–20 years, so don’t be surprised if you notice any fault in a 10-year-plus building. What you can do to a broken seal is to properly reseal it, and it isn’t as complicated as you may think.

This straightforward guide breaks the process down into simple steps. We’ll walk through everything you need to know on how to reseal windows. Let’s start by outlining why proper window sealing is important.

Why Is Sealing Windows Important?

Resealing broken window seals does more than a cosmetic face-lift; it also saves you money and ensures productivity in the following ways:

1. Reduces Energy Waste

Air leaks mean your heating and cooling units have to work harder to keep your office comfortable. When you reseal double-glazed windows, you can significantly improve their energy efficiency and lower your utility bills. You can reduce heat loss through windows by up to 40% just by sealing air leaks.

2. Improves Comfort

Drafts and cold spots in your office building can make some rooms unusable and reduce your overall comfort. Eliminating air leaks around windows helps ensure even temperatures throughout your office so you can enjoy every space.

3. Protects Windows

Moist air leaks can lead to condensation buildup on and around your windows, which damages the seals, frames, and window panes over time. Preventing excess moisture in and around your windows helps extend their lifespan and reduces damage like rot, corrosion, and mould growth. Resealing windows is one of the ways to stop condensation in windows.

4. Increases Building Value

Properly sealed, energy-efficient windows are an attractive selling point in case you are planning to sell your building. Weatherising your windows helps ensure maximum efficiency and can increase your office’s resale value. For many managers, the additional value to their property far exceeds the cost of professional window sealing.

Increasing building value

Given that seal breakage may not always be evident, how do you determine it’s time to do a window reseal? Continue reading to know the different signs to look out for.

When to Reseal Windows: 4 Signs You Need New Window Seals

If you’re noticing issues with your windows like fogging, drafts or increased energy bills, it’s probably time to consider sealing window frames outside. This can help you differentiate between when to repair uPVC windows and when to replace them.

1. Condensation and Fogging

If you see condensation or fogging building up between the panes of glass in your windows, that means the airtight seal has been compromised. This is one of the double-glazing problems to look out for to ensure maximum efficiency. When moist air gets in and condenses, it reduces visibility and can lead to water damage if left unaddressed.

2. Higher Energy Bills

Poorly sealed windows are energy hogs since the conditioned air inside your office is escaping outside. Your heating and cooling system has to work harder to compensate, driving up your utility bills. Resealing or replacing worn-out windows can significantly improve the energy efficiency of your office building.

3. Drafts and Noise

If you feel cold air leaking in around your windows or doors or notice outside noises are more audible inside, it’s a sign that your seals have lost their ability to insulate properly. New seals will reduce drafts, keep more of the conditioned air in your office, and block outside noise.

4. Cold Spots

Run your hands around the edges of windows and doors, especially on cold days. If certain areas feel noticeably colder, that indicates where air is leaking in due to seal failure. Resealing or replacing those seals will make your windows fully functional and energy efficient once again.

By keeping an eye out for the above signs in your building, you can determine when it’s right to do a window reseal. Given the high cost of replacing windows, understanding these signs and their implications can help you avoid unnecessary costs. And if you decide to embark on a DIY window reseal, the below supplies are what you’ll need to get started.

Supplies Needed for Resealing Windows

To undertake a DIY exterior window sealing project, you’ll need a few essential supplies. Having the right tools and materials on hand will make the job go much more smoothly.

Supplies for resealing windows

Here is what you will need:

1. Caulking Gun

A caulking gun is a must-have for applying sealant around the edges of your windows. You’ll want a high-quality gun that can handle window sealants. Look for one with an easy-grip handle, built-in sealant cutter, and drip-control mechanisms.

2. Putty Knife

A putty knife or sealant tool is useful for smoothing out the sealant bead and scraping up any drips or spatters.

3. Sealant

The window seal you choose depends on the material of your window pane and frame. For vinyl or aluminium, use a high-quality polyurethane or silicone sealant. For wood frames, an elastomeric sealant works well. In either case, look for a sealant that’s specifically intended for sealing around windows and doors.

Additional Tools

Other useful items to replace window seals include:

  • Gloves to protect your hands
  • Mineral spirits for cleaning up the work area
  • Drop cloths or plastic sheeting to protect surfaces from sealant drips
  • Paint brushes/rollers/extensions for larger sealing jobs

With the right tools and a careful, meticulous approach, resealing your windows is a DIY-friendly task. Now, let’s walk you through how to seal a window in a few steps!

A 5-Step Guide to Resealing Window Frames

When sealing windows, a quality job is key to energy efficiency and comfort. As an office manager, this is a task you can definitely handle yourself.

Steps of resealing windows

Follow these 5 steps on how to reseal windows inside and get your office sealed up tight:

  • Use a utility knife to remove the old sealant.
  • Clean the frames.
  • Apply the sealant.
  • Seal the corners.
  • Check your work.

1. Use a utility knife to remove the old sealant.

First, use a utility knife to carefully cut away as much of the old caulk or sealant from around the window frame as possible.

2. Clean the frames.

Clean the frames with a silicone remover or mineral spirits to remove any remaining residue. Wipe the frames down with a damp cloth to remove any dirt or debris. Once dry, wipe the frames again with rubbing alcohol to degrease them. This will help the new sealant adhere properly.

3. Apply the sealant.

With clean frames, you’re ready to apply the new window sill seal. For most windows, a quality silicone or polyurethane sealant works well. Load the sealant into a caulk gun and apply it around the edges of the window frame, using a smooth and steady motion. Aim for about a 1/4-inch bead, and use a damp finger or caulk tool to smooth the sealant and push it firmly against the frame.

4. Seal the corners.

Pay extra attention to sealing the corners where the sealant meets. Apply sealant to one side, then use the caulk tool or your finger to push the sealant into the corner. Repeat on the adjacent side, pushing the sealant together in the corner to create an airtight seal. Use a damp rag to wipe away any excess sealant from the glass panes.

5. Check your work.

Once complete, do a final check of all the window frames, looking for any gaps in the sealant, especially in the corners. Use a utility knife to cut away and re-seal any problem areas. For best results, consider doing one final pass with a damp rag to ensure perfectly clean and sealed windows. Your efforts will be well worth it when your energy bills decrease and your building’s comfort increases.

Check your work

While undertaking this DIY project yourself can save you hundreds compared to hiring a pro, we recommend hiring the leak repair services of a professional window glazier to handle larger projects and to ensure it’s done right. GLRE is the go-to glazing replacement and refurbishment service provider in the UK — drop a message for us to schedule an appointment. 

Frequently Asked Questions

Can you reseal windows yourself?

Yes, you can reseal windows yourself, but it’s a complex task best left to professionals. DIY resealing might not guarantee the functionality of your double-glazed windows, so for optimal results, hiring a window specialist is highly recommended.

Is it worth getting windows resealed?

Yes, resealing windows is worthwhile, especially if you’re experiencing condensation between panes, drafts, or visible damage to the seals. Properly resealed windows enhance insulation, reduce energy costs, and improve the comfort of your building.

How much does it cost to reseal windows in the UK?

In the UK, resealing a window typically costs between £50 and £65, accounting for labour charges of £40 to £50 per window and a minimum service fee. These prices can vary based on the specific requirements of the job and the number of windows you need to be resealed.


That’s all there is on how to reseal windows like a pro. If you follow these steps carefully, you’ll be able to breathe new life into those drafty old windows. Just take it slow and steady — don’t rush through it, or you might end up with leaks. Double-check your work as you go, and you’ll have weatherproof windows in no time.

Now, you can relax knowing cold drafts won’t be sneaking into your office buildings this winter. However, remember not to handle more than you can comfortably seal. Window resealing can get complicated depending on the type of building and how many windows need resealing. Such complex tasks are best handled by professional glaziers — contact the GLRE team today!

No items found.

Newsletter Signup

Signup to receive our email newsletter providing you with the latest GR updates, offers and more.
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.

Book a Site Survey

Book an inspection from the UK’s leading glazing refurbishment company.