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How To Install Glass In Steel Window Frames

One of the most critical components of any glass extension is the installation of the glass itself. While it may seem straightforward, installing glass in steel window frames can be challenging, especially for those new to DIY projects. But if you’re hesitant to take on such a large project, replacing broken glass or installing new glass in window frames is achievable with the right tools and guidance. In this article, we’ll take you through the process, step-by-step, with expert advice and insider tips on how to install glass in steel window frames quickly and easily.

Safety is a priority

Safety is always a priority when taking on any DIY project, and installing glass in steel windows is no exception. Before you start, you must ensure you have all the necessary safety measures to protect yourself and those around you.

It’s essential to wear protective safety gear, such as work gloves, safety glasses, hi-vis clothing, and a dust mask. These items will help prevent any injury or potential illness from the materials used during the installation process, including any hazards from the glass and any sealants or adhesives used.

Additionally, it’s important to be aware of any potential hazards that may be present in your home. If your property was built before 1992, there’s a chance lead paint may be present on walls or woodwork, which can be harmful if ingested or inhaled. And, if your home has insulation or ceiling tiles installed before the 1990s, there may also be a risk of asbestos, which can also be dangerous to your health.

To ensure your safety, you must check for these materials and have them tested and removed by a licensed professional before starting any DIY project, even if you intend to focus only on installing glass in steel window frames. Taking the necessary precautions and being mindful of potential hazards can ensure a safe and successful installation process.

Preparing to install a glass window

When installing glass into steel window frames, preparation is key to making them safe, secure, energy-efficient, and watertight. Before you start, gathering all the necessary tools and materials to ensure a smooth and safe installation process is essential – we’ll look into those below.

Beyond this, the most critical part of any window installation is taking precise measurements. Using a tape measure, measure the height and width of the opening in the steel frame, taking note of any irregularities or size variations. It’s crucial to measure accurately so your new glass is cut to fit precisely and doesn’t leave any gaps or spaces that could allow air or water to penetrate the frame.

What tools and materials do you need?

Once you’ve measured your glass, you’ll be ready to go. Here’s a checklist of the tools and materials you’ll need to install your new windows into steel frames.

  • Safety gloves
  • Safety glasses
  • Hi-vis workwear
  • Certified dust mask
  • Glazing putty (suitable for steel frame windows)
  • Putty knife
  • Pliers
  • Heat gun or hairdryer
  • Sandpaper
  • New window or spring clips
  • Chisel or a flat-head screwdriver
  • Rubber mallet
  • Masking tape

Always remember that installing glass can be difficult and dangerous. Demolishing and removing old glass means small, loose pieces can cut you or get into your eyes. So always wear the appropriate protective gloves, clothing, and safety glasses to avoid injury.

Remove putty

Removing old glazing putty from a glass window can prove difficult, but ensuring a secure and tight fit for your new window is essential. First, use the putty knife to gently loosen the putty around the edges of the old glass window. Be careful not to apply too much pressure, which could damage the glass or steel frame.

Placing a heat gun or hairdryer a few inches away from the putty can loosen it, making it soft, pliable, and easier to remove using the pliers. Once you’ve removed all the putty, use your sandpaper to sand and smooth the area.

Remove window clips

Before removing the old glass, remove any window or spring clips holding it in place. First, locate the window or spring clips on the side and top of the frame. If necessary, use the screwdriver to pry the clip away from the frame before using pliers to grip each clip to pull it out gently. Repeat this process for all clips around the window, taking care not to damage the steel frame.

Remove the old glass

Once you’ve removed all the clips, you’ll need to remove the glass window from the steel frame, taking care not to break the glass or damage the frame. Using a rubber mallet, you can gently tap the glass to break it enough to remove it safely.

To avoid large shards when removing it, use masking tape to create a cross pattern on the glass in the shape of a Union flag. Once the main glass is removed, there will still be a few broken edges remaining, and you can use your pliers to remove them. Use safety gloves and goggles to protect your hands and eyes from sharp edges or fragments.

Install the new glass

Before installing your new glass, cleaning up any mess around the steel window frames, such as old putty, dust, and debris, is crucial. Use a putty knife or scraper to remove any debris from the frame you may have missed, and ensure it’s clean and smooth before the new glass goes in.

Once you’ve done this, prepare your new glazing putty by rolling it into a ball and making a long sausage to line each inside edge of the steel frame. After this, bed the glass into the new putty at the bottom of the frame and tilt it upwards, pushing the glass against the putty on each edge.

Use new window clips or spring clips to secure the new glass in place, ensuring they’re evenly spaced and secure. Then remove any excess putty before adding more putty to the other side of the glass in the same way. Use the putty knife to press the putty down, smooth it out, and remove any excess.

Glazing putty can take up to 14 days to dry completely, so try to avoid touching it before then. Finally, you can clean any remaining debris around the window and use a spray cleaner to clean the glass to remove any dirt, marks, or smudges.

Steel windows and doors from GlasSpace

While the steps above show you how to install glass in steel window frames at home, you may only feel comfortable installing glass into smaller or medium-sized windows. Glass in more oversized steel windows and doors can prove more difficult to replace yourself and will need the expertise of qualified glaziers, like our team at GlasSpace.

As specialist manufacturers of steel windows and doors, together with our frameless glass house extensions and glass box extensions, our team are more than qualified to design and install the perfect glass facade to extend your living space. With minimalist aesthetics and slimline frames, the elegance is second to none compared to many alternative systems.

For more information on our steel windows and doors or any glass products, contact us today or email We’ll be happy to discuss your ideas and plans, advise you on all the details, and offer you a free, no-obligation quote.

At glasspace we encourage you to take advantage of our complimentary design consultation with an advisor who will have the expertise and knowledge to assist you with a structure that is right for you.

Taking your brief and ideas we can design for you. If you have an Architect or designer, we will collaborate to ensure your new bespoke glass structure is the best it can be.

GlasSpace’s structures are unique and not made up of standard parts so designers have the freedom to express your idea.