Unitized vs Stick Built Curtain Wall
The question every facade specifier faces: factory-built modules or site-assembled grid? This guide compares both systems on the nine criteria that decide real projects — with honest numbers from our engineering team.
Factory modules vs site assembly
Unitized curtain wall
Full floor-height modules — framing, glass, spandrels, gaskets and seals — are assembled in the factory, pressure-tested in batches, then transported and crane-lifted into position. The module arrives as a closed, already sealed element; site crews only connect and gasket the joints between modules.
Stick built curtain wall
Mullions are anchored to the slab, transoms span between them, and glass or panels are glazed in on site. Every step — alignment, drainage, sealing — happens in the open air. It is the traditional method, and for the right building it remains the smartest value play.
Nine criteria compared
| Criterion | Unitized | Stick Built | Winner |
|---|---|---|---|
| Erection speed | 8–15 m²/day/crane | 3–5 m²/day/team | Unitized |
| Tooling / setup cost | High (design, jigs, lift) | Low | Stick built |
| Unit cost per m² | Higher | Lower baseline | Stick built |
| Quality control point | Factory, batch-tested | On site, crew-dependent | Unitized |
| Weather exposure during build | Closed rain-screen fast | Open grid until sealed | Unitized |
| Geometry flexibility | Module grid constraints | Site-adjustable | Stick built |
| Seismic / inter-storey drift | Rotational joints absorb drift | Needs engineered slip joints | Unitized |
| Logistics & site constraints | Needs crane + storage | Works with skylifts, tight sites | Stick built |
| Best height range | > 50–60 m towers | ≤ 50–60 m mid-rise | Depends on height |
The 50–60 m crossover explained
Below the crossover height, stick built wins on total cost: no tooling, no crane, simpler logistics. Above it, wind loads rise, erection time dominates the critical path, and the unitized advantage in speed and closed-layer QC shrinks or reverses the cost gap.
The crossover is not a fixed number — it moves with facade area, floor plate, site access, local labor rates and program. That is why Hanart models both options in early-stage cost studies rather than applying rules blindly.
Run the interactive selector to see which fits your project →
When to mix both systems
Unitized modules on the tower for speed and QC; stick built on the podium where geometry changes floor by floor and budgets are tighter.
Special corner or parapet zones often switch to stick built detailing because module grids cannot economically follow complex folds.
Mixing works only with careful interface detailing — thermal, movement, sealant and tolerance continuity between the two systems are designed together, not improvised on site.
Unitized vs stick built questions, answered
Unitized curtain walls are pre-assembled in factory as full floor-height modules and crane-lifted into place, closed already sealed. Stick built systems are assembled on site from mullions, transoms and infill panels. The difference drives cost, program, QC and weather exposure during erection.
Unitized has a higher unit cost due to tooling, module fabrication and crane logistics, but it is faster to install. On tall towers the schedule saving usually outweighs the premium; on mid-rise buildings stick built is typically the lower total-cost solution.
As a rule of thumb, 50–60 m is the crossover. Below it, stick built is usually cheaper. Above it, the speed, QC and weather-tightness of unitized modules make them competitive or cheaper on total cost and program.
Quality depends on the contractor, not just the system. Unitized moves quality control into the factory with sealed test units; stick built depends on disciplined site assembly and sealing. Both can and must pass the same mock-up air, water and structural tests.
Yes, and it is common: unitized for the tower, stick built for the podium, or unitized for rainscreen-heavy zones and stick built for irregular corners. Interface detailing between the two systems is the key engineering task.
Not sure which system your building needs?
Send your elevations today and we'll return a system recommendation with cost and program comparison — both options modeled, not guessed.