What is the difference between curtain wall and cladding?
Installing an exterior building envelope and confused about these two systems? Curtain walls are structural glazing systems that transfer loads to the building frame, while cladding is non-structural exterior surfacing that only protects against weather. Understanding these differences could save you 30-60% on facade costs depending on your project requirements.
The key distinction is structural function - curtain walls are self-supporting systems spanning multiple floors (handling wind loads up to 120psf), whereas cladding merely attaches to substrates (supporting only its own weight, typically <10psf). Curtain walls use aluminum mullions and insulated glass units (IGUs), while cladding employs panels of metal, stone, or composites fixed to backup walls.
Let's analyze the specific technical differences:
How do structural capabilities compare?
These systems handle building stresses completely differently:
Structural Performance Comparison
| Feature | Curtain Wall | Cladding |
|---|---|---|
| Load Transfer | Direct to structure | Through substrate |
| Wind Resistance | 80-120 psf | 10-30 psf |
| Seismic Movement | 1.5-2.5% drift | 0.5-1% drift |
| Span Capability | 12-25 feet | 3-8 feet |
| Deflection Limit | L/175 | L/120 |
Key structural components:
- Curtain Wall: Aluminum frames (6063-T5/T6 alloy), shear blocks, expansion joints
- Cladding: Z-girts, carrier channels, hat sections
- Connections: Curtain walls use anchor bolts; cladding uses screws/clips
What about installation and maintenance?
The construction processes differ significantly:
Installation Comparison
| Process | Curtain Wall | Cladding |
|---|---|---|
| Lead Time | 12-20 weeks | 4-8 weeks |
| Installation | Top-down sequence | Bottom-up |
| Tolerance | ±1/8" | ±1/4" |
| Access | Swing stages | Scaffolding |
| Maintenance | Every 15-20 years | Every 8-12 years |
Typical installation costs:
- Curtain Wall: $50-$150/sq ft
- Cladding: $20-$80/sq ft
- Anchorage: CW=$8-12/sf vs Cl=$2-5/sf
- Sealants: CW=30LF/sf vs Cl=15LF/sf
How do material options differ?
Available facade materials vary by system type:
Material Options
| Material | Curtain Wall | Cladding |
|---|---|---|
| Aluminum | 75% of projects | 40% of projects |
| Glass | 100% (IGUs) | 5% (spandrel) |
| Stone | 0% | 15% |
| Metal Panels | 0% | 25% |
| FRP | 0% | 5% |
| Terracotta | 5% | 10% |
Thickness comparisons:
- Mullions: 3-12" deep (CW) vs 1-3" (Cl)
- Panels: N/A (CW) vs 3/16"-2" (Cl)
- Insulation: Continuous (CW) vs Cavity (Cl)
- Fire Barriers: 1hr rated (both)
What are the waterproofing approaches?
Weather protection strategies contrast substantially:
Water Management Comparison
| Method | Curtain Wall | Cladding |
|---|---|---|
| Primary Barrier | Gaskets | Membrane |
| Secondary | Pressure Equalized | Drained Cavity |
| Testing | ASTM E331 | AAMA 501.2 |
| Joint Width | 1/2"-1" | 1/4"-1/2" |
| Drainage | Weep Holes | Flashing |
Performance standards:
- Air Infiltration: CW=0.06cfm/sf @1.57psf vs Cl=0.1cfm/sf
- Water Penetration: CW=15% design pressure vs Cl=20%
- Thermal Cycling: CW=150 cycles vs Cl=50 cycles
Which is better for high-rises vs low-rises?
Application suitability varies by building height:
Project Type Recommendations
| Building | Preferred System | Why |
|---|---|---|
| Skyscrapers | Unitized CW | Handles high winds |
| Mid-Rise | Stick CW | Balanced cost |
| Low-Rise | Cladding | Economical |
| Industrial | Cladding | Impact resistant |
| Curved Forms | Cladding | More flexible |
Hybrid solutions exist:
- Window Wall: Combines CW windows with cladding spandrels
- Rainscreen: Cladding over backup CW
- Structural Glazing: Cladding panels with CW attachments
While curtain walls provide sleek, high-performance glazing for prestige projects (80% of towers over 40 stories), cladding offers economical, durable protection for most low/mid-rise buildings. The choice ultimately depends on budget (cladding averages $45/sf vs CW $90/sf), desired aesthetics, and structural requirements. Many contemporary buildings combine both - using curtain walls for vision areas and cladding for spandrels/soffits.
