Thermal Performance in Flush Track System

Thermal Performance of Minima Sliding Doors

Thermal performance with the Flush Track System begins at compliance and goes well beyond it. UK Building Regulations set a minimum overall U-value of 1.2 for glazed elements — the Ultraline system matches this with double glazing and reaches 0.7 with triple glazing, placing it comfortably ahead of most alternatives on the market.

Ultraline 4 panel sliding doors with glass to glass corners installation Watford

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Reduce your utility bills with high performance glazing

Our high-performance double glazed argon-filled units feature low-e glass with black warm edge spacer bars.

Benefit from a thicker glazed unit

Our glazed units have an overall unit thickness of 36mm, made up of 6mm, 8mm or 10mm glass panes. Other systems are 28mm as standard.

Leave a smaller carbon footprint

Our sliding doors achieve an overall u-value of 1.2 with double glazing and 0.7 with triple glazing. The minimum u-value required for building regulations compliance is 1.2.
With u-values, the lower the number, the better the u-value. Our door system goes above and beyond the requirements.

Add laminated glazing as necessary

Laminated glazing upgrade is available for compliance with Part Q (Security) of building regulations if required.

Upgrade glass options

Opting for triple glazing will improve the overall u-value to 0.7. This upgrade is available if needed but is restricted to panel sizes of up to 5.4m².
A solar control glazing upgrade which improves the g-value is available if needed.

Glass Specs

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Does the Flush Track System meet UK Building Regulations for thermal performance?

Yes. The system achieves an overall U-value of 1.2 with double glazing, which meets the minimum requirement under current UK Building Regulations. With triple glazing, this improves to 0.7 — significantly better than the regulatory minimum.

What makes the glazed units more thermally efficient than standard systems?

The glazed units used in our system are 36mm in overall thickness for double glazing unit (46mm for triple glazing) compared to the 28mm standard found in most competing systems. They feature low-emissivity (low-e) glass, argon-filled cavities, and black warm edge spacer bars — all of which contribute to reducing heat transfer through the unit.

Is triple glazing available with the Flush Track System?

Yes. Triple glazing is available as an upgrade and improves the overall U-value to 0.7. It is compatible with panels up to 5.4m² in size. The triple-glazed option is particularly well suited to north-facing openings, exposed coastal locations, or projects targeting high energy performance ratings.

What is solar control glazing and when should I consider it?

Solar control glazing includes a coating that reduces the amount of solar energy transmitted through the glass, improving the g-value of the unit. It’s worth considering for south-facing or west-facing openings with large glass areas where overheating in summer could be an issue. The upgrade is available on both double and triple glazed configurations.

Do the doors require any additional thermal upgrades to comply with Part L of the Building Regulations?

No — the standard double-glazed Ultraline system already meets the 1.2 U-value requirement set by Part L as standard. If your project targets a higher specification — for example, Passivhaus or Future Homes Standard compliance — the triple glazing and solar control options can be used to achieve lower U-values.

Related Features

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Visual Advantages

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Functional Benefits