At AT-ECO, we’ve installed hundreds of Internorm systems across Kent, Sevenoaks, and beyond—on both period homes and new-build developments. As a certified Internorm partner, we’ve seen first-hand how their advanced technology and materials translate into exceptional thermal performance, security, and durability.
Here’s what sets Internorm apart—and why it’s our top recommendation for clients seeking long-lasting, future-ready windows and doors.
1. Multi-Material Construction for Peak Performance
Internorm's flagship products—like the HF410 (Timber-Aluminium) and KF410 (uPVC-Aluminium)—combine:
- Warm Internal Layer: Timber or uPVC for thermal stability and natural interior finishes
- Precision-Injected Thermal Foam: For high insulation, vapour resistance, and rigidity
- Powder-Coated Aluminium Exterior: Maintenance-free and weatherproof
AT-ECO Insight: We’ve installed HF410s on countryside homes near London and across the country. Where clients requested timber warmth inside but needed protection against exposed weather conditions—Internorm delivered both, beautifully.
How It Compares:
| Feature | Internorm (HF/KF Series) | Standard uPVC Frame |
|---|---|---|
| U-value potential | Up to 0.62 W/m²K | 1.4–1.8 W/m²K |
| Structural Integrity | Triple-layer composite | Hollow chambered plastic |
| Exterior Protection | Powder-coated aluminium | Bare or foiled plastic |
| Interior Finish | High-grade timber/uPVC | Basic white plastic |
2. Premium Timber = Longevity & Aesthetics
Internorm selects only knot-free, high-stability timber, precision-tested for warping and cracking resistance. Each profile is finished with multiple protective coatings, ensuring durability and design consistency.
AT-ECO Feedback: Homeowners in Tunbridge Wells have noted how Internorm’s timber frames remain pristine years later—no bowing, cracking, or moisture damage like they experienced with cheaper joinery.
3. Triple-Gasket Sealing for Thermal and Acoustic Comfort
Internorm’s windows include a three-gasket system, forming a continuous, airtight perimeter seal that:
- Minimises air and water infiltration
- Enhances thermal performance
- Blocks external noise—even from busy roads or flight paths
Real-World Case: During a recent project on a detached property in Kent, AT-ECO installed Internorm triple-glazed systems, including the HF 410 and HS 330. The result? A 70% improvement in energy efficiency over the client’s previous setup, along with a dramatic drop in draughts and noise—exceeding expectations and delivering Passive House-level performance with a modern, refined aesthetic.
4. Design That’s Functional and Elegant
Every detail of an Internorm window is considered—from engineering to finish:
- Ergonomic Handles: Comfortable, durable, and minimalist
- Swiss ISO-Spacers: Reduce condensation, improve edge insulation
- Concealed Hinges & Hardware: Clean lines and easier cleaning
- Flush Rebate Interiors: Round profiles trap less dust—ideal for low-maintenance living
Design Note: Architects regularly praise Internorm’s frameless or slim-profile options for blending contemporary style with passive house-grade performance.
5. Built for Easy Maintenance
Durability doesn’t end at structure—it extends to user experience. Internorm’s systems are designed with low-maintenance finishes:
- Powder-coated exteriors backed by a 10-year colour guarantee
- Rebate geometry that minimises dirt collection
- Internal timber surfaces that resist scratches and UV fading
AT-ECO Advice: In areas with high pollen or salty air (e.g., coastal Kent), Internorm systems reduce the need for constant cleaning—saving both time and long-term upkeep costs.
6. FIX-O-ROUND® Glazing Technology
This patented glazing method bonds the glass unit all around the sash for:
- Maximum torsional stability—critical in large glass areas
- Enhanced burglar resistance
- Greater thermal insulation by eliminating weak perimeter points
Performance Insight: We regularly use FIX-O-ROUND® on floor-to-ceiling installations. It provides the structural confidence our clients demand—especially in exposed or high-spec self-builds.
How Internorm Outperforms Standard Systems
| Feature | Internorm | Conventional Alternatives |
|---|---|---|
| Frame Construction | Triple-layer composite | Single-material (uPVC or Alu) |
| Timber Selection | Grade A+, knot-free | Lower-grade softwoods |
| Sealing System | Triple-gasket | Double gasket or basic sealant |
| Noise Reduction | Up to 44 dB | 32–36 dB typical |
| U-Value Range | 0.62–0.90 W/m²K | 1.4–1.8 W/m²K typical |
| Glazing Integration | FIX-O-ROUND® bonded | Partially fixed bead glazing |
Final Thoughts: Performance That Pays Off
Internorm systems aren’t just about sleek finishes or triple glazing—they’re about delivering lasting performance, low energy bills, and a home that stays comfortable no matter the season.
At AT-ECO, we’ve spent years helping homeowners and architects integrate Internorm’s products into homes that need to meet Part L efficiency targets, overheating reduction strategies, and aesthetic design ambitions. Whether you're after a Passive House-certified build or want low-maintenance performance with luxury finishes, Internorm delivers—and we install it right.
