When planning an extension or new opening to a garden, sliding doors are often one of the most important design decisions. Two of the most commonly specified systems from Sunflex are the SVG20 and SVG30, both high-quality aluminium sliding doors but designed for different applications.

This guide explains the key differences between SVG20 and SVG30, when each system works best, and how to choose the right option for a Surrey home.

In Brief

The Sunflex SVG20 is a slimmer, more design-led sliding door system suited to lighter-duty residential applications, while the SVG30 is a heavier-duty system designed for larger openings, higher traffic areas and increased structural demands. The right choice depends on opening size, usage and detailing rather than appearance alone.

What are Sunflex SVG20 and SVG30?

SVG20 and SVG30 are sliding door systems, not bifold or folding systems, and are typically specified where uninterrupted views and smooth linear movement are preferred. 

Overview of the SVG20 system

SVG20 is typically chosen where:

• Openings are moderate in size

• A slimmer frame profile is preferred

• The doors are primarily residential in use

It is often specified on:

• Standard rear extensions

• Smaller openings

• Projects where visual lightness is a priority

Overview of the SVG30 system

SVG30 is engineered for more demanding situations, including:

• Larger and wider openings

• Heavier door panels

• High-traffic or multi-use spaces

It is commonly used on:

• Large kitchen–living extensions

• Openings with higher wind exposure

• Projects where long-term durability is critical

Both SVG20 and SVG30 are aluminium sliding door systems designed for large glazed openings, offering smooth operation and clean sightlines without folding or stacking panels. You can view full specifications, configuration options and design details on our Sunflex aluminium sliding door systems page. 

Key differences between SVG20 and SVG30

Although both systems share Sunflex build quality, there are important technical differences that affect suitability.

Frame strength and panel capacity

SVG30 is designed to accommodate:

• Heavier glass units

• Larger individual door leaves

• Greater structural loads

SVG20 is better suited to lighter configurations where extreme panel weights are not required.

Opening size and configuration

For wider spans or more complex configurations, SVG30 offers greater flexibility. SVG20 performs very well within its intended size range but is not designed for the same extremes.

Usage and durability

On projects where doors are opened and closed frequently or used as a primary access point, SVG30’s heavier-duty components can offer greater long-term resilience.

Which system is best for Surrey extensions?

Surrey homes often combine large glazed openings with design-sensitive detailing, making correct system selection important.

Typical Surrey use cases for SVG20

SVG20 is often suitable for:

• Family homes with moderate-sized extensions

• Projects prioritising slim sightlines

• Situations where door use is occasional rather than constant

Typical Surrey use cases for SVG30

SVG30 is more appropriate where:

• Openings are large or structurally ambitious

• The doors form a major connection between inside and outside

• Long-term robustness is a priority

Choosing the wrong system for the opening size is one of the most common mistakes we see.

You can see how a Sunflex sliding system performs in a real project by viewing a recent Sunflex sliding door installation on a Surrey home.

Thresholds, drainage and detailing

Regardless of system choice, correct detailing is critical.

Threshold height considerations

Threshold selection affects:

• Accessibility

• Weather performance

• Internal floor levels

The chosen system must align with finished floor levels and external drainage design.

Installation quality matters

Even the best bifold system will underperform if:

• Structural openings are inaccurate

• Thresholds are poorly detailed

• Drainage is not properly considered

System selection and installation must be treated as a single process.

Planning, compliance and performance

Both SVG20 and SVG30 can be specified to meet current Building Regulations when configured correctly. Performance figures depend on:

• Glass specification

• Door size and configuration

• Installation quality

Early coordination with the wider build team helps avoid late-stage compromises.

Frequently Asked Questions

Is SVG30 always better than SVG20?
No. SVG30 is not “better” in all cases — it is simply designed for more demanding applications. SVG20 is often the right choice for standard residential projects.

Can SVG20 be used on large openings?
SVG20 performs best within defined size limits. For larger or heavier configurations, SVG30 is usually more appropriate.

Do both systems look the same once installed?
Visually, they are similar. The main differences relate to engineering, capacity and long-term performance rather than appearance.

Which system lasts longer?
Both are durable systems, but SVG30 is designed to cope better with higher loads and heavier usage over time.

If you’re planning a Surrey extension and are unsure whether SVG20 or SVG30 is right for your opening, early advice can help ensure the system selected matches both the design intent and practical requirements of the project.