# Polyamide Thermal Break Strip in Aluminium Profiles

> A polyamide thermal break strip is a glass-fibre-reinforced polyamide 66 bar rolled mechanically into two separate aluminium extrusions, joining them into one profile while breaking the metal path between inside and outside. It is a structural component, and a deeper strip lengthens the thermal path and improves the frame U-value.

## What it is

A **glass-fibre-reinforced polyamide bar** rolled mechanically into two
separate aluminium extrusions, joining them into one profile while breaking the
metal path between inside and outside.

It is structural. The window's strength depends on the strip and on how well it
was rolled in.

## Specification at a glance

| Property | Typical specification |
| --- | --- |
| Material | Polyamide 66, approximately 25% glass fibre |
| Standard | EN 14024 for mechanical performance |
| Depth | 14mm — 34mm and above; **state it** |
| Shape | Straight bar, or shaped for higher performance |
| Assembly | Knurled, inserted and roll-crimped |
| Verification | Shear test on the assembled profile |

## Why the rolling process matters

The strip is held by mechanical crimping of the aluminium around it. If the
knurling is shallow, the rolling pressure wrong, or the profile tolerance out,
the composite fails in shear — the two aluminium halves move relative to each
other under load or temperature.

That failure shows up as a window that racks, a sash that stops closing, or
sealant joints that tear. It is not visible at handover.

EN 14024 exists to verify exactly this, and the certificate should be for the
profile as assembled, not for the strip as supplied.

## Where projects go wrong

- **Strip depth unspecified**, so the U-value in the compliance calculation
  does not match what was installed.
- **Thermal break omitted entirely** on air-conditioned buildings, then
  condensation blamed on the HVAC design.
- **Poor rolling quality** from a fabricator without the right line.
- **Mixing broken and unbroken profiles** in one system, leaving a cold bridge
  at the weakest member.
- **Shear certificate for the strip alone**, which proves nothing about the
  assembled profile.

## Standards referenced

Thermal barrier profile mechanical performance under **EN 14024**. Fenestration
U-value targets under **ECBC 2017**. Aluminium sections under **IS 733**.

## Frequently asked questions

### What is the strip actually made of?

Polyamide 66 reinforced with about 25 percent glass fibre. The glass fibre gives it the stiffness and dimensional stability to act as a structural member between the two aluminium halves, and the polyamide gives the low thermal conductivity. It is a load-bearing component, not a gasket, which is why its material specification and the quality of the rolling process both matter.

### Does strip depth change performance much?

Substantially. A deeper strip lengthens the thermal path between inside and outside, so frame U-value improves as depth increases — the difference between a shallow 14mm strip and a deep 34mm one is significant in the overall window calculation. Specifying a thermally broken profile without naming the strip depth leaves the actual performance open, and the shallowest option will be cheapest.

### Is a thermal break needed in Indian conditions?

For air-conditioned buildings, yes. An unbroken aluminium frame conducts heat inward continuously, and in humid weather the inner face runs cold enough for condensation to form on the frame, which occupants report as a leaking window. The case is strongest for conditioned commercial space and weakest for naturally ventilated buildings where there is no cold inner surface.

## Sources

- [EN 14024](https://standards.cencenelec.eu/ords/f?p=CEN:105) — Metal profiles with thermal barrier — mechanical performance
- [ECBC 2017](https://beeindia.gov.in/) — Building envelope — fenestration U-value
- [IS 733](https://standards.bis.gov.in/website/published-standards/department-wise) — Wrought aluminium alloy sections

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Source: https://hagerstone.com/materials/polyamide-thermal-break-strip