Schuco AS FD 75 vs AS FD 90.HI Bifold Doors Compared

Schuco's current bifold range is built around two flagship systems, the AS FD 75 and the AS FD 90.HI, and choosing between them is one of the more common decisions homeowners face once they have settled on Schuco over other aluminium brands. Both are systems we fabricate and install in-house at our Uxbridge workshop, and the right choice comes down to how much thermal performance and frame depth your project actually needs.

The AS FD 75 — Schuco's Standard Specification

The AS FD 75 is Schuco's current standard bifold system and the one specified on the great majority of contemporary UK extensions. It replaced the older ASS 70.HI Bifold as Schuco's default recommendation for new projects, offering slim sightlines, a wide range of panel configurations and colour options, and the whole-window thermal performance expected on a modern rear extension. For most homeowners planning a kitchen-diner opening onto a garden, the AS FD 75 is the specification that fits the brief without over-engineering the project.

The AS FD 90.HI — the Passivhaus-Grade Upgrade

The AS FD 90.HI is the deeper, higher-performance sibling in the range, built around an extra-wide thermal break for projects where the brief is Passivhaus certification, Future Homes Standard 2026 compliance, or an especially exposed elevation such as a large north-facing aperture. The 90.HI in the name reflects the deeper frame profile that carries the improved thermal break, and it is the system we specify when a project's energy targets genuinely require it rather than as a default upgrade.

Frame Depth and Sightlines

The AS FD 90.HI's deeper frame buys thermal performance, and that depth is visible in a slightly heavier sightline compared with the AS FD 75. On a standard domestic extension the difference is modest and rarely the deciding factor on its own, but on a project where an architect has specified the slimmest possible sightlines throughout, the AS FD 75 is generally the closer match. Among Schuco's bifold range, the AS FD 75 sits toward the slimmer end without compromising on certified security or weather performance.

Thermal Performance

Both systems are thermally broken and rated for UK domestic use, with the AS FD 90.HI engineered for the more demanding end of the performance scale. Exact whole-window figures depend on the glazing specification chosen and are confirmed at survey, but as a rule of thumb the AS FD 90.HI is the system to specify when the project has a defined energy target to hit, such as Passivhaus or an EPC-driven renovation, rather than a general preference for "the best possible" performance.

Security and Certification

Both the AS FD 75 and AS FD 90.HI are PAS 24 certified across their opening profiles, with multi-point locking, internally beaded glazing and anti-snap cylinder hardware as standard. Secured by Design accreditation is available as an upgrade on either system where an insurer specifically requires it. Security specification does not differ meaningfully between the two ranges, so it should not be the deciding factor when choosing between them.

Which System Should You Choose?

If your project is a standard rear extension with no specific energy certification target, the AS FD 75 is the sensible default: slimmer sightlines, the full range of configurations and colours, and performance well suited to UK domestic use. If your brief includes Passivhaus, Future Homes Standard 2026 compliance, or an unusually exposed elevation, the AS FD 90.HI is worth the additional frame depth. We talk through both options at survey against your specific brief before recommending one.

We fabricate and install the Schuco AS FD 75 and AS FD 90.HI bifold door systems in-house at our Uxbridge workshop. Every installation is FENSA registered and carries a 10-year CPA insurance-backed guarantee.

Frequently Asked Questions

What is the main difference between the Schuco AS FD 75 and AS FD 90.HI?

The AS FD 90.HI has a deeper frame profile built around an extra-wide thermal break, giving it higher thermal performance suited to Passivhaus or Future Homes Standard 2026 projects. The AS FD 75 is Schuco's standard specification with slimmer sightlines, suited to the great majority of standard extensions.

Do I need the AS FD 90.HI for a normal extension?

Not usually. Most standard rear extensions are well served by the AS FD 75. The AS FD 90.HI is worth specifying when the project has a defined energy performance target or an especially exposed elevation.

Is the AS FD 90.HI more secure than the AS FD 75?

No, security certification is comparable across both ranges. Both are PAS 24 certified as standard, with Secured by Design available as an upgrade on either system where required.

Can the AS FD 75 and AS FD 90.HI be matched in colour and configuration?

Yes. Both systems are available across Schuco's standard colour range and a wide range of panel configurations, so the choice between them can be made on performance and frame depth without limiting your design options.

Which Schuco bifold system should I choose for a Passivhaus project?

The AS FD 90.HI is the system built for that brief. Its deeper thermal break is engineered specifically for projects with demanding energy performance targets, confirmed against your specification at survey.