Internally vs Externally Glazed Windows: What’s the Difference?

When selecting new windows for your property, choosing between internally glazed windows and externally glazed windows is a crucial decision that significantly impacts security, maintenance, and energy efficiency.

At Admiral Windows, we've been helping homeowners across Oxfordshire and beyond make informed window choices since 1986. Understanding these glazing differences is essential for optimal home performance.

What Are Internally Glazed Windows?

Internally glazed windows feature glass panels secured by glazing beads positioned on the interior side of the frame. This means the glass is held in place from inside your property, making the glazing beads accessible only from within. This modern approach has become the preferred choice for window installation due to its superior security and performance benefits.

As FENSA-registered installers, we at Admiral Windows Oxford supply and fit internally glazed windows as standard, ensuring that your home stays safe, warm, and secure.

Interior view of an internally beaded window

Exterior view of PVCu internally beaded window

Interior view of an internally beaded aluminium bi-fold door

What Are Externally Glazed Windows?

Externally glazed windows have their beading strips on the outside face of the frame.

In older windows (particularly from the 1980s and 1990s), this could make it possible to remove the glass unit from the outside, posing a security risk.

Modern externally glazed windows are designed with added safety features, such as wedge gaskets, which must first be removed from inside before the external beading can be taken out. However, this design is less common in today’s installations.

Outside view of older PVCu windows, showing obvious beading strips

Security Comparison

The most significant difference between these glazing methods lies in security. Internally glazed windows offer superior protection against break-ins because the glazing beads cannot be accessed from outside the property. Potential intruders cannot simply remove the beads to extract the glass panel, making forced entry considerably more difficult.

Externally glazed windows present a security vulnerability since the glazing beads are exposed on the outside. With the right tools, someone could potentially remove these beads and access the glass from the exterior, creating an easy entry point. This makes externally glazed windows particularly unsuitable for ground-floor installations or accessible upper-floor windows.

Maintenance and Durability

Maintenance requirements differ significantly between the two systems. Internally glazed windows protect the glazing beads from weather exposure, reducing wear and deterioration over time. The seals and beads remain in better condition for longer periods, requiring less frequent replacement or maintenance.

Externally glazed windows expose their glazing systems to harsh weather conditions, UV radiation, and temperature fluctuations. This exposure can cause the glazing compound or beads to degrade more quickly, potentially leading to seal failure, drafts, and reduced energy efficiency. Regular inspection and maintenance become more critical with external glazing.

Energy Efficiency and Thermal Performance

Both glazing methods can achieve excellent thermal performance when properly installed with quality materials. However, internally glazed windows often provide slightly better long-term energy efficiency due to their superior seal integrity over time. The protected glazing system maintains its thermal properties longer, ensuring consistent performance throughout the window's lifespan.

The weatherproofing challenges associated with external glazing can sometimes compromise thermal efficiency as seals deteriorate, potentially allowing air leakage and reducing the window's insulating properties.

Should You Replace Older Externally Glazed Windows?

If your property still has older externally glazed windows, we strongly recommend considering an upgrade. The reasons are clear:

• Security – older glazing systems are easier to tamper with.

• Energy efficiency – modern frames and glazing units significantly outperform those from 20+ years ago.

• Aesthetics – new windows enhance kerb appeal and add value to your property.

Replacing outdated windows is one of the best investments you can make for your home.

Cost Considerations

Initially, both glazing methods have similar manufacturing and installation costs. However, internally glazed windows often prove more economical over time due to reduced maintenance requirements and longer-lasting seals. The enhanced security features may also qualify for insurance discounts in some cases.

Externally glazed windows might require more frequent maintenance visits and earlier replacement of glazing components, potentially increasing long-term ownership costs.

Making the Right Choice

For most residential applications, internally glazed windows represent the superior choice, offering enhanced security, reduced maintenance, and reliable long-term performance. They're particularly recommended for ground-floor installations, accessible windows, and properties where security is a primary concern.

Externally glazed windows may still be suitable in certain commercial applications or historic renovations where maintaining an authentic appearance is essential, provided additional security measures are implemented.

Consider your property's specific requirements, local climate conditions, security needs, and long-term maintenance preferences when making your decision. For professional guidance tailored to Oxfordshire properties, consulting with experienced window specialists ensures you choose the glazing method that best serves your particular situation.

Choose Admiral Windows Oxford – Your Local Experts

Since 1986, Admiral Windows Oxford has been supplying and fitting high-quality double glazing for nearly 40 years. Our products combine modern security features, excellent insulation, and stylish designs tailored to your home. As a FENSA-registered and TrustMark-accredited company, we guarantee professional installation of internally glazed windows that meet the highest industry standards.

Our experienced team understands the unique requirements of properties in Oxfordshire, from period homes in the city centre of Oxford to modern developments across the county and beyond. As standard, install internally glazed windows to ensure maximum security, energy efficiency, and long-term performance for our customers.

Whether you’re looking to replace older externally glazed units or upgrade to the latest energy-efficient windows, our team is here to help.

Contact Admiral Windows Oxford today to arrange your free, no-obligation consultation and quote.

Call us on 01865 788333

Email us at sales@admiralwindows.co.uk