Introduction
Glass facades (Curtain Wall and Spider Glass) today form the main part of the modern architecture of luxury and commercial towers in Iran. These facades offer minimalist beauty and maximum light intake, but the presence of a seismic joint creates a major challenge: how can we provide ±200 to ±400 mm of movement without ordinary aluminum profile lines destroying the facade’s transparency and beauty?
In this comprehensive article, we will technically and practically examine how to implement Agor seismic joint covers in glass facades in such a way that both full seismic performance is achieved and the facade remains completely integrated and transparent. We will also introduce the specialized Agor Ehtad models designed for this application.
What is a seismic joint in glass facades and why is it challenging?
In glass facades, the seismic joint usually appears as a vertical or horizontal strip between two Curtain Wall modules. According to Iran’s Code 2800 and America’s ASCE 7-22, the width of this joint is between 50 and 400 mm, and the designed movement is ±150 to ±500 mm.
Main challenges:
- Ordinary aluminum covers with a width of 100–150 mm create black or silver lines that disrupt the transparency of the facade.
- Sealing at high altitudes exposed to strong winds is very difficult.
- Wind load transfer and three-dimensional movement (longitudinal, transverse, vertical) must be provided without damaging the glass.
To better understand the calculation of joint width, read the article Accurate calculation of seismic joint width in high-rise towers.
Main challenges of implementing seismic joint covers in transparent facades
1. Maintaining aesthetics and visual integrity
Architects do not want thick aluminum profiles to create visible lines.
2. Complete sealing at height
At altitudes above 100 meters, wind pressure up to 2 kPa and heavy rain cause water penetration.
3. Withstanding seismic movement without damaging the glass
Heavy laminated glass (up to 50 kg/m²) may crack or delaminate during intense movement.
4. Light transmission and thermal insulation
The cover should not reduce light transmission or create a thermal bridge.
If your project is in harsh weather conditions, the article The effect of Iran’s climate on the performance of seismic joint covers provides useful information.
Technical solutions for transparent seismic joint covers in glass facades
1. Using transparent multi-wall polycarbonate
- Light transmission up to 92%
- 1/10 the weight of glass
- Impact resistance 250 times that of glass
2. Low-profile aluminum profiles (Slim Profile)
- Visible width less than 30 mm
- Black or clear anodized to integrate with Curtain Wall frame
3. Point-Fixed and Spider Glass systems
- Connection without visible frame
- Free movement with 316L steel spiders
4. Special laminated glass with SGP interlayer
- Crystal clarity
- Delamination resistance during intense movement
Specialized Agor Ehtad products for glass facades
FacadeCrystal series – Transparent polycarbonate cover
- Thickness 20–50 mm
- Movement ±400 mm
- Slim aluminum frame with 25 mm visible width
- Implemented in towers of District 1 in Tehran and Kish
GlassJoint series – Point-Fixed laminated glass
- 12+12+1.52 SGP glass
- Connection with frameless steel spiders
- Suitable for completely transparent Spider Glass facades
View the complete catalog of these series at Agor Ehtad facade seismic joint cover products.
Comparison table of seismic joint cover solutions for glass facades
| Solution | Transparency (%) | Visible width (mm) | Movement (±mm) | Weight (kg/m²) | Approx. cost (million/m²) | Best application |
|---|---|---|---|---|---|---|
| Multi-wall polycarbonate | 88–92 | 25–40 | 400 | 3–5 | 12–20 | Luxury facades, high light intake |
| SGP Point-Fixed laminated glass | 91–93 | Frameless | 200 | 45–50 | 35–50 | Spider Glass facades |
| Slim aluminum profile | 0 (low-profile) | 20–30 | 300 | 8–12 | 10–18 | Standard Curtain Wall |
Guide for selecting and installing seismic joint covers in transparent facades
1. Assess the designed movement: If movement is above ±300 mm, use polycarbonate
2. Review aesthetic requirements: Completely transparent: GlassJoint series, low-profile: MinimalLine series
3. Installation method:
- Connection to Curtain Wall substructure with adjustable brackets
- Sealing with Dow Corning 991 clear silicone
- Movement testing with hydraulic jack in the workshop
4. Final testing
- Water penetration test (AAMA 501)
- Seismic movement test (±500 mm)
Implementation tips and challenges in glass facades
- Challenge 1: Wind load transfer Solution: Use steel brackets with 5 kN capacity
- Challenge 2: Different thermal expansion Solution: 5–8 mm thermal gap and PTFE washer
- Challenge 3: Installation at height Solution: Use suspended scaffolding and a team certified for working at height
- Challenge 4: Long-term cleaning Solution: Hard-Coat coating on polycarbonate with 6H hardness
Case study: Commercial tower in District 1, Tehran (2024-2025)
- Facade type: Curtain Wall + Spider Glass
- Joint width: 280 mm
- Facade height: 120 meters
- Solution: FacadeCrystal series with 40 mm polycarbonate
- Result:
- Light transmission 90%
- No visible lines
- Cost 18 million Tomans/m²
- Complete satisfaction of architect and employer
Conclusion
Implementing seismic joint covers in glass facades requires a precise balance between seismic performance, sealing, and aesthetics. Using multi-wall polycarbonate, low-profile profiles, or Point-Fixed systems (Agor Ehtad’s FacadeCrystal, GlassJoint, and MinimalLine series) is the best solution to maintain transparency and visual integrity of the facade.
For free technical consultation and to receive a 3D rendering of the seismic joint cover for your project’s glass facade, send the facade plan. The Agor Ehtad team will provide a complete proposal within 48 hours.
FAQ
1. Is the transparent polycarbonate seismic joint cover resistant in a glass facade?
Yes, its impact resistance is 250 times that of glass, and with the Hard-Coat layer, it remains scratch-resistant for up to 15 years.
2. What is the maximum frameless transparent joint width?
In the FacadeCrystal series, up to 400 mm with polycarbonate.
3. How much does a transparent cover cost compared to an ordinary aluminum profile?
2–3 times more, but the aesthetic and light intake value of the facade is completely justifiable.